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CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES
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INTERVENTIONAL CHEST RADIOLOGY
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CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES Charles S. White, MD, Cristopher A. Meyer, MD, and Philip A. Templeton, MD
The recent introduction of CT continuous imaging, also called real-time CT and CT fluoroscopy, has improved the ease of performing interventional thoracic procedures. This article discusses the use of CT fluoroscopy to facilitate percutaneous needle aspiration biopsy and pleural drainage in relation to established techniques. We also describe our experience in applying CT fluoroscopy for a newer application, guidance of transbronchial bronchoscopic biopsy. PERCUTANEOUS NEEDLE ASPIRATION: CURRENT IMAGE GUIDANCE TECHNIQUES
Percutaneous needle aspiration was first reported in the late 18OOs, and the imageguided approach for sampling of lung nodules came into widespread use in the 1960s.2 Conventional fluoroscopy was initially used and permits direct visualization of the nodule during sampling. Biplane fluoroscopy allows improved ease of biopsy. Based on several studies, the accuracy of fluoroscopically guided biopsy is 61% to 97%.2' Fluoroscopy remains the guidance technique of choice in many practices, but is not suitable for every lesion. Small nodules may be difficult or impossible to identify. The ac-
curacy for biopsy of lesions greater than 2 cm is 80%, as compared with 60% for lesions less than 1 cm. Lesions smaller than 1 cm may be difficult to visualize and low-density or indistinct nodules often are difficult to detect. Another important limitation of conventional fluoroscopy is that some lesions may be superimposed on and not separable from normal thoracic structures, such as the hila and mediastinum. In some instances, biopsy using fluoroscopic guidance may not be advisable if the nodule is adjacent to a major cardiovascular structure, such as the aorta.25 Several investigators have reported thoracic biopsy results using ultrasound guidance.6,23* 32 Advantages of ultrasound include real-time imaging and lack of ionizing radiation. Sonography is limited by attenuation of the beam as it traverses air-filled lung, however, obscuring nodules that are deep in the lung. Intraoperative ultrasound has been used to localize pulmonary nodules during thoracoscopy because the lung is a i r l e s ~U1.~ trasound is best used to facilitate biopsy of pulmonary nodules that abut the pleural surface. Standard CT is the most commonly used technique for lung biopsy and is safe and accurate. Sensitivity exceeds 90% for malignant lesions, although it is somewhat lower for benign nodules.29For small lung nodules
From the Department of Diagnostic Radiology, University of Maryland School of Medicine, Baltimore, Maryland (CSW, CAM, PAT); currently, the Department of Diagnostic Radiology, University of Cincinnati Medical Center, Cincinnati, Ohio (CAM)
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(those less than or equal to 1.5 cm), CT is the optimal technique. Two studies have reported biopsy success rates of 74% and 93%, respec30 Both studies emtively, for small nod~les.~, phasized the advantage of CT in guiding the approach of the needle toward the nodule and to document localization of the needle tip within the nodule. Standard CT has several limitations that are a consequence of the lack of real-time visualization. It may take several attempts to localize the nodule and achieve proper angulation of the needle toward the nodule. With each adjustment, the biopsy team must leave the scanning room while the new needle location is confirmed. Respiratory motion may alter the relationship of ribs and other structures with respect to the nodule and compensation can be difficult in the absence of realtime observation. Moreover, the actual sampling of the lesion is not observed directly to ensure that the needle tip is within the nodule. CT FLUOROSCOPY FOR LUNG NODULES: EQUIPMENT The technical specifications of the continuous-imaging (fluoroscopic)CT scanner are de-
scribed elsewhere. A brief summary is provided here.3* Like most standard CT scanners, fluoroscopic CT uses slip-ring (spiral) technology. The real-time visualization is achieved in part by the use of a rapid array processor and fast reconstruction algorithm that permits rapid image reconstruction and display. An in-room control panel and monitor permits the radiologist, wearing standard fluoroscopic radiation protection, to perform and view CT images while remaining in the scanning room (Figs. 1 and 2). The control panel allows in-room activation of the laser light and scanner and manipulation of table position and height and gantry angle. Movement of the table is achieved with either a joystick on the control panel or a manual sliding mode, which allows the radiologist to slide the table freely. The monitor and control panels are freestanding and can be positioned optimally for each procedure. The radiologist can put sterile drapes on the control panel and the foot of the table and perform the entire procedure without assistance. Alternatively, an assistant can operate the monitor and table. A button on the control panel or a foot-pedal identical to that used for routine fluoroscopy is depressed to activate real-time imaging. The choice of needle is dependent on the
Figure 1. CT fluoroscopy suite demonstrates the integrated monitor, control panel and gantry. Note the sterile cover over the control panel that permits the radiologist to operate the CT fluoroscopy system and manipulate the catheter without compromising sterile technique. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998; with permission.)
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Figure 2. CT fluoroscopy control panel. The left joystick adjusts gantry angle and the right joystick controls table movement. Additional functions include: power, laserlight, localizer, table height, freehand sliding mode table position, and emergency weight-off switch. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:10971101, 1998; with permission.)
size and location of the lesion and amount of tissue required; the risk of complications (e.g., pneumothorax); and the preference of the operator. If the radiologist wishes to view the nodule while the needle is being advanced or during sampling, a modification of technique is often necessary to avoid exposure of the hand holding the needle to the primary radiation beam. One approach to overcome this problem is to use a needle-holder during biopsy. One device that has been designed is an acrylic resin screw lock device with a handle that projects perpendicular to the needle shaft. The operator advances the needle with the handle allowing the hand to stay outside of the primary beam. A simpler method of avoiding the primary beam is to grasp and direct the needle with a surgical clamp while performing the biopsy in real time. CT FLUOROSCOPY OF LUNG NODULES: OPERATOR TECHNIQUE
CT fluoroscopic biopsies can be performed using either a real-time or an interrupted realtime operator technique. The real-time technique uses direct visualization by CT fluo-
roscopy while the needle is being advanced and during biopsy of the nodule itself. A perpendicular needle-holding device is necessary to avoid direct exposure of the operator’s hand to the primary radiation beam. Katada et a17 have described three variations of the real-time approach: (1) breath-hold method, (2) couch-sliding technique, and (3) controlled-respiration technique. The breath-hold method is simplest and is useful for biopsy of lesions in the upper part of the lung. The table remains stationary, the patient suspends respiration, and the nodule is sampled. The couch-top sliding method is valuable if the lesion has shifted out of the imaging plane because of patient movement. This technique consists of moving the couch-top longitudinally to locate both the lesion and needle tip in the same imaging plane, facilitating puncture of the needle. The controlled-respiration technique was found to be valuable in patients with lesions near the diaphragm. With this technique, the patient is instructed to expire fully before scanning. After scanning is initiated, the patient inhales slowly. When the maximal diameter of the lesion comes into the imaging plane, the patient suspends respiration and the biopsy is per-
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formed. Advantages of the real-time technique include the ability to document needle location within the nodule as it is being aspirated.7Movement of the needle into the nodule (puncturing) or pushing away of the nodule (balloting) by the needle can be observed. The second basic biopsy technique has been termed the interrupted real-time technique. With the interrupted real-time technique, needle advancement and nodule biopsy are not directly visualized but are rapidly confirmed after each advance of the needle using a short pulse of fluoroscopy, often without removing the patient from the gantry. When the needle tip is clearly identified within the nodule, aspiration is done blindly or using direct visualization. Advantages of the interrupted real-time technique as compared with the real-time technique described previously include the increased distance of the operator from the primary beam, reducing exposure from radiation and eliminating the need for a needle holder." The improved tactile sensation provided by direct contact with the biopsy needle during aspiration is advantageous. A further advantage is that more complex biopsy techniques, such as a coaxial approach, or an automated biopsy device (gun), can more easily be used in conjunction with the interrupted real-time method. A potential disadvantage of the use of the interrupted method is that visualization of complications of the procedure might be delayed. This delay is minimal, however, as compared with conventional CT. CT FLUOROSCOPY TO GUIDE NEEDLE BIOPSY EARLY CLINICAL RESULTS
Reports of clinical experience with the use of CT fluoroscopy to guide percutaneous needle biopsy are limited. In the study of Katada et a1,7 results of 60 CT fluoroscopic procedures were reported in 57 patients, including 36 with CT-guided intrathoracic procedures. Among thoracic procedures, the target nodule was punctured on the first attempt in 83% of patients and the average number of passes for all nodules was 1.3. Diagnostic specimens were obtained in 32 (97%) of the 33 patients who underwent lung biopsy and included 17 malignant and 15 benign lesions. In a single 7 x 10 mm lesion, the needle tip was visualized in the nodule but there was insufficient
tissue for diagnosis. Mean time for the procedures was 54 minutes (range, 24 to 139 mi,nutes). An average of 74 seconds of CT fluoroscopy time was used for each puncture. There were 17 (47%) complications among the 36 thoracic procedures, including one episode of hemoptysis and 16 pneumothoraces. Three pneumothoraces were treated with aspiration of pleural air and two required placement of a chest tube. The authors concluded that the real-time capability of the CT fluoroscopy permitted reduction in the number of needle punctures required to do the biopsy and provided substantial overall advantages over standard CT. Our preliminary experience using CT fluoroscopy to assist in the biopsy of small pulmonary nodules is also promising.21We studied 17 patients with nodules of 1.5 cm or less. In most cases, we used a coaxial biopsy technique and the interrupted real-time CT fluoroscopy method (Figs. 3 and 4). As on standard CT, the needle tip was routinely identified by its characteristic low-density artifact (Figs. 5 and 6). We obtained diagnostic tissue in 16 (94%) of the 17 lesions, including 11 malignant and 5 benign nodules. The nondiagnostic biopsy occurred in a small, deep lesion in which the procedure was discontinued after a single pass. At surgery, this lesion proved to be a non-small cell carcinoma. The mean lesion depth in our study was 7 cm. The mean number of passes was 2.5. For these small lesions, the mean fluoroscopic time for each puncture was 103 seconds. Image quality was good using 30 mA and 120 kilovolt (peak). Average room time was 91.5 minutes. Nine patients (53%)in our series developed complications, including one with hemoptysis and eight with pneumothorax. Two patients with pneumothoraces required chest tube drainage. The rate of success and complications in the two series is ~irnilar.~,It is likely that the increased number of punctures required in our series is because of the smaller size of the nodules. The longer room time in our series may be due to the small size of the nodules and other factors, such as extra time needed for supervision of a resident or fellow. In addition to use of CT fluoroscopy to assist interventional procedures in the lung, we have found CT fluoroscopy guidance Valuable to obtain biopsies of lesions in the pleura and paraspinal region, mediastinum, and chest wall (Figs. 6 and 7). For these areas,
CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES
Figure 3. A 56-year-old man with a 1.5-cm left upper lobe nodule. Image from a CT fluoroscopy segment shows the needle traversing an area of bullous disease (arrow) posterior to the nodule. (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
Figure 4. A 50-year-old woman with an irregular small density in the periphery of the left upper lobe. The needle is directed toward the lateral margin of the lesion. Biopsy showed adenocarcinoma of the lung. (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209218, 1999; with permission.)
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Figure 5. A 56-year-old woman with a subpleural lesion in the left lower lobe. Note the low attenuation artifact that arises from the tip of needle (arrowhead) indicating its position within the tumor. Biopsy revealed adenocarcinoma of the lung. (From White CS, et al: CT Fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
the real-time capability may permit the operator to avoid traversing lung parenchyma. Although it is a subjective impression that CT fluoroscopy allows biopsies to be obtained more rapidly it is important to recognize that no study has directly compared the duration of procedures done with standard CT and CT fluoroscopy to ascertain if there is a decrease in procedure time with the latter. Likewise, other purported advantages of CT fluoroscopic guidance have not been compared directly with standard CT. CT FLUOROSCOPY FOR GUIDING PERCUTANEOUS BIOPSY SUMMARY
As compared with techniques other than CT, CT fluoroscopy shares with standard CT the advantages of excellent spatial resolution, a wide field of view, optimal imaging of airfilled structures, limited operator dependence for obtaining images of good quality, and the ability easily to place the biopsy needle in the imaging plane. Standard CT is impeded by the necessity to acquire a series of images after each movement of the biopsy needle,
however, requiring the radiologist to exit the scanning room for each acquisition. Further time elapses as the images are reconstructed and displayed and any patient movement may change the needle position in relation to anatomic landmarks. CT fluoroscopy obviates leaving the scanning room because images are available in the room and are observed in real time. In our study, we estimated that the use of CT fluoroscopy resulted in a decrease of 2 to 4 minutes per needle adjustment as compared with standard CTJ1 Several potential advantages of the realtime capability of CT fluoroscopy have been described. These include the ability visually to time the biopsy puncture more easily with the phase of respiration, avoiding ribs and other intervening structures. CT-fluoroscopic guidance may facilitate placement of the needle preferentially at the edge of the lesion, which is useful in masses with a necrotic center. If the real-time technique is used, the nodule may be seen to be pushed away (balloted) by the needle, indicating the need for a more rapid puncture technique. The real-time imaging afforded by CT fluoroscopy permits rapid diagnosis of complications. It is common to recognize hemorrhage around the nodule after biopsy and a needle track is often observed on withdrawal of the needle (Fig. 8). Few of these patients develop hemoptysis. Pneumothoraces are recognized quickly so that appropriate management can be instituted (Fig. 9). An important subjective advantage of CT fluoroscopy is the increased peace-of-mind that it provides for the radiologist. The short time interval between movement of the needle and knowledge of its location and any complications can substantially decrease stress related with the procedure. There are few disadvantages to the use of CT fluoroscopy for thoracic procedures. Concern has been raised about excessive radiation exposure that may occur in versions of CT fluoroscopy offered by certain vendors. In our experience, the radiation dose has been well within acceptable limits. CT FLUOROSCOPY USE IN ASSISTING INTRATHORACIC DRAINAGE PROCEDURES
Image-guided chest drainage procedures have become commonplace in the treatment of parapneumonic effusions; malignant effu-
CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES
Figure 6. A 48-year-old man with a mass involving the upper thoracic vertebral body with paraspinal extension. A, CT fluoroscopic image shows the needle traversing the left transverse process and rib in an extraparenchymal course (arrow). €I, Subsequent image shows the needle tip in the left paraspinal mass, as indicated by the low attenuation artifact that emanates from it (arrowhead). (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
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Figure 7. A 67-year-old man with multiple left pleural nodules. Image from a CT fluoroscopic segment demonstrates the needle within a pleural nodule. Biopsy showed sarcoidosis. (From White CS: CT Fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lntelventional Radiology 16:209-218, 1999, with permission.)
sions; pneumothoraces; and occasionally, mediastinal fluid collections. Image-assisted thoracic drainage of loculated pleural collections has a consistently higher success rate than blindly inserted thoracostomy tubes. Radiology drainage tubes are, in general, more easily positioned, smaller in caliber, and better tolerated by the patient.22Methods of imaging-guided insertion include fluoroscopy, ultrasound, and CT. These topics have been reviewed in detail recently.*,14,18, 20, 26
CHOICE OF IMAGING MODALITY
Many factors are involved in the selection of the appropriate imaging modality for drainage of intrathoracic collections.These include the characteristics of the thoracic collection, patient parameters, and the radiologist's specific modality expertise. Size, location, and contents of the collection are characteristics that should be considered when selecting the appropriate imaging modality. In general, large fluid collections and free-flowing collections are most easily and rapidly drained using ~ l t r a s o u n d . Ultra'~ sound is the modality of choice because it lacks ionizing radiation, is portable, and allows real-time visualization of needle and catheter placement. A free-flowing collection may be difficult or impossible to approach
with CT guidance because the fluid collection tends to move to a dependent position in the chest. Although homogeneous collections are easily localized and drained sonographically, complex fluid collections and air cannot be distinguished from underlying aerated lung parenchyma and may require CT guidance.17 The location of the fluid collection helps to determine the choice of modality. The radiologist must ensure that there is adequate visualization of intervening vessels, particularly the internal mammary and mediastinal great vessels, which may be easier using CT. Finally, patients who are unable to suspend respiration present a challenge to the placement of large drainage catheters. Using CT fluoroscopy the expected route of access to the fluid collection can be visualized throughout the respiratory cycle. This allows the radiologist to coordinate needle placement with an adequate window to avoid damage to intervening structures." PLEURAL DRAINAGE
In our experience, the most common request for pleural drainage is to treat parapneumonic effusion or empyema." Up to 50% of patients with pneumonia have accompanying pleural fluid.l, lo, l9 The choice of treatment depends on the fluid characteristics (i.e., transudate versus exudate). In general, a tran-
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Figure 8. A 65-year-old woman with a right lobe nodule. A, CT shows a smoothly marginated nodule medially in the right lower lobe (arrow). 6,Image from a CT fluoroscopic segment shows the needle adjacent to the nodule. Note the hemorrhage that has occurred along the needle track and around the nodule from an earlier biopsy pass (arrows). The second pass revealed non-small-cell carcinoma.
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Figure 9. A 61-year-old man after successful left upper lobe biopsy. A, CT fluoroscopy image obtained moments after the needle was withdrawn shows a moderate anterior pneumothorax. B, CT fluoroscopic image after placement of a pleural drainage catheter shows appropriate location of the catheter and minimal residual pneumothorax. (From White CS: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:20%218, 1999; with permission.)
sudate or simple parapneumonic effusion responds to the antibiotic therapy; most drainage catheter placements are reserved for exudative effusions, either infectious, inflammatory, or neoplastic. Techniques for pleural drainage using CT fluoroscopy are similar to those for standard CT. The patient is scanned using the real-time capabilities of the CT scanner to plan the site of access to the pleural collection for optimal drainage and patient comfort. Care should be taken to identify a route that avoids the intercostal artery, vein, and nerve that run on the undersurface of each rib. The patient is
prepared and draped in sterile fashion and a sterile cover is placed over the control panel. The procedure may then be performed either in real time by watching the Seldinger needle or trocar advance into the pleural fluid collection or with an interrupted real-time technique. We have generally used the latter technique because it minimizes exposure to the operator's hands. With this technique, the needle is advanced in a stepwise manner with short applications of fluoroscopic CT to confirm the needle and catheter path." The radiologist stays in the CT suite and initiates CT fluoroscopy by the control panel. The patient
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Figure 10. A 50-year-old man with leukemia and right focal pleural fluid collection after treatment of Nocardia pneumonia. A pigtail catheter was placed in this posterior fluid collection using a modified Seldinger technique. Following evacuation of 20 cc of brown purulent material, the patient's fever abated and he recovered uneventfully with antibiotics.
remains within the gantry throughout the process of needle placement for improved efficiency. Access to the pleural fluid may be accomplished using either a trocar or modified Seldinger technique. Generally, large pleural fluid collections that are not adjacent to critical vascular structures may be accessed using a single stick method with a 12F to 14F catheter. We prefer hydrogel-coated catheters for ease of traversing fascial planes." The stiffness of these catheters also prevents kinking once they are placed. We have had several instances in which a locked catheter that had been placed in an inflammatory fluid collection remained locked after thread release. We place only self-forming pigtail catheters in the pleural space. A modified-Seldinger technique should be used for technically challenging collections. In these patients, a 19-gauge Seldinger entry needle is placed into the thoracic collection under CT fluoroscopic guidance. Subsequently, a 0.038-in (0.097 cm) Bentsen guidewire is placed through the needle and coiled in the pleural collection. The tract is expanded with serial fascial dilators to 12F catheter. A 14F pigtail catheter is passed over the guidewire using the hollow stiffening stylet to keep the catheter straight. The stylet is fixed in position and the catheter is advanced off the stylet into the pleural collection. Dilatation and catheter placement are accom-
plished with the patient outside the CT gantry and without imaging observation. Subsequent documentation of catheter placement and, if necessary, manipulation are performed under direct CT fluoroscopic observation (Fig. 10). Complex fluid collections with loculation may require the placement of multiple drainage catheters or intrapleural fibrinolytics. MEDIASTINAL COLLECTIONS Mediastinal fluid collections and abscesses are uncommon but technically challenging to access and drain effectively. Mediastinal collections that may require drainage include postoperative abscesses, especially those following esophageal surgery (Fig. 11);infected mediastinal duplication cyst; lymphocele; Boerhaave's syndrome, or mediastinal pancreatic pseudocyst.26Image-guided mediastinal drainage is technically similar to pleural drainage procedures but care is necessary to avoid laceration of the internal mammary vessels, great veins, or arteries as the catheter is advanced. For this reason, CT fluoroscopy offers a substantial advantage over current imaging modalities because it permits realtime observation of the needle path." We have also used CT fluoroscopy to drain a loculated anterior pericardial collection while observing the relationship of the catheter to
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Figure 11. A 77-year-old man with mediastinal mucocele 2 years after an emergency esophagectorny for perforation. A, Initial CT fluoroscopy performed for placement of a 19-gauge Seldinger needle into the fluid collection. B,After guidewire placement and tract dilatation, a pigtail catheter is confirmed to be in the collection. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998; with permission.)
the right ventricle as the collection was drained (Fig. 12). PNEUMOTHORAX Thoracostomy tube placement is useful for a large, symptomatic, or enlarging pneumothorax. Radiologists may be required to place a chest tube after a transthoracic needle biopsy. We occasionally place small-bore thoracostomy tubes for loculated pneumothoraces in patients who have undergone lung volume reduction surgery, lung transplantation, or in
patients on a ventilator with the adult respiratory distress syndrome. Such patients may be at increased risk of intraparenchymal tube placement because of pleural adhesions. CT-guided pneumothorax drainage follows the same basic steps described for the drainage of pleural fluid collections. Smaller-bore chest tubes are usually effective (8F to 10F catheter) but a 12F to 14F catheter tube may be necessary for large pleural tears. Placement of pneumothorax tubes varies based on pneumothorax location and the patient’s functional status. Insertion of a catheter for an anterior pneumothorax is relatively
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Figure 12. A 42-year-old alcoholic man with poor cardiac output and a pericardial fluid collection. A, A 20-gauge angiocatheter needle (arrow) has been advanced into the collection parallel to the right ventricle under fluoroscopic guidance. B, The collection is smaller following aspiration. On real-time imaging, cardiac pulsation could be visualized deviating the needle, and the procedure was electively terminated.
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straightforward. CT fluoroscopy may be useful in guiding catheter placement in a complex, loculated pneumothorax." In one case, CT fluoroscopic assistance allowed us to place a drainage tube in a loculated major fissural pneumothorax by observing a small window along the su erolateral chest wall during the expiratory p ase of respiration (Fig. 13).
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CT FLUOROSCOPY USE IN ASSISTING TRANSBRONCHIAL NEEDLE ASPIRATION
Transbronchial needle aspiration (TBNA) is useful to diagnose central parenchymal le-
sions and sample mediastinal nodes. Nodal status has important implications for the staging and prognosis of lung cancer. Although mediastinoscopy, mediastinotomy, and thoracoscopy are valuable techniques for mediastinal staging, TBNA with bronchoscopic guidance is frequently used to sample abnormal lymph nodes that are located near an airway?, 24, 27 Lymph nodes in the subcarinal and right and left paratracheal regions are most easily aspirated. One important limitation of TBNA as compared with surgical techniques is that the target node is not visible through the bronchoscope. The bronchoscopic needle may be advanced through the airway wall using
Figure 13. A 59-year-old man with shortness of breath and a loculated pneumothorax after lung volume reduction surgery. A modified Seldinger technique was used to access the major fissure through a 1-cm pleural window. A, CT fluoroscopic image with the 19gauge Seldinger needle accessing the major fissure, while avoiding adjacent lung parenchyma (arrow). 6,CT fluoroscopic image after decompression with an 8F catheter. The patient was symptomatically improved, although the pneumothorax is incompletely drained. Illustration continued on opposite page
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Figure 13 (Continued). C, CT fluoroscopic image after exchanging the 8F catheter for a 12F catheter with improved decompression. This tube was placed to 20 cm H,O Pleur-Evac suction. Note thrombus (T), which was present before imaging intervention. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-I 101, 1998; with permission.)
landmarks identified on the preprocedure CT scan and distortions or bulges of the airway encountered during the procedure. Conventional fluoroscopy is often used to guide TBNA and improve the yield of the procedure. This technique is limited, however, by the overlap of structures in the mediastinum produced by the two-dimensional fluoroscopic display. In many instances the enlarged mediastinal lymph node is not distinguishable using conventional fluoroscopy. The inability of fluoroscopy to provide adequate visualization of the target lymph node has limited widespread use of TBNA. Moreover, it has fueled the perception that TBNA is difficult, potentially dangerous, and should be practiced only by experienced bronchoscopists. Most series have indicated that the technique is inferior to that of surgical series with sensitivity ranging from 37% to 90%.24,27 Many patients who might be candidates for bronchoscopically guided TBNA are referred for surgery. Sonographic assistance of TBNA, in which an ultrasound probe is inserted into the bronchoscope,16 is an alternative guidance technique that currently suffers from two limitations. First, the diagnostic quality of the sonographic images is variable; it may be difficult to distinguish lymph nodes from other anatomic structures. The technique is highly
operator dependent. Second, the ultrasound probe is passed through the same port that is used for the biopsy needle. The probe must be withdrawn and the bronchoscopic position maintained while the needle is inserted. Realtime visualization is not achieved. Standard CT can also be used to image the location of the bronchoscope within the airway in relation to the target lymph nodes.I5 Rong and CuilS reported 60% sensitivity in diagnosing mediastinal adenopathy by TBNA using standard CT guidance. Similar to its use for percutaneous needle biopsy, however, standard CT is cumbersome because a substantial time delay occurs while the appropriate slice position is found, the technologist prescribes the sequence and scans the patient, and image reconstruction occurs. While this occurs, the bronchoscope must be maintained in a constant position for several minutes. This sequence of events must be repeated for each adjustment of the bronchoscope. The ability of CT fluoroscopy to provide real-time imaging is valuable in guiding TBNA.31 Using CT fluoroscopy, each movement of the bronchoscope can be verified quickly on the in-room monitor. The bronchoscopic needle is visualized as it is planted in the airway to ensure that it is directed toward the intended biopsy site. Once the needle has been advanced, CT fluoroscopy is used to
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ensure that the needle is in the target lesion. Complications, such as pneumothorax or hemorrhage, are documented quickly. For lesions in which an initial nonsurgical approach is contemplated, the location of the abnormality determines whether percutaneous needle biopsy or TBNA is performed. Peripheral lesions, particularly those that are
in a subpleural location, are most easily sampled using a percutaneous technique. Central lesions and especially those in which a bronchus extends into the lesion, are optimally diagnosed using bronchoscopy with TBNA. Large central lesions are diagnosed routinely using bronchoscopy with or without fluoroscopic guidance, particularly if an endobron-
Figure 14. An 62-year-old man with a 3-cm right middle lobe nodule and mediastinal adenopathy. A, Enhanced CT scan obtained to stage the patient shows an enlarged subcarinal lymph node (arrow). B, CT fluoroscopic image of initial pass demonstrates the needle (arrow) to the right of the node. Only bronchial wall cells were obtained. Illustration continued on opposite page
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Figure 14 (Continued). C, CT fluoroscopic image reveals the bronchoscopic needle within the node (arrow). A diagnosis of non-small cell lung cancer was obtained.
chial component is present. Smaller lesions are more problematic and require fluoroscopic guidance. Conventional fluoroscopy, however, is limited in guiding TBNA if the lung nodule is very small. Moreover, it is often difficult to determine the anteroposterior relationship between the needle tip and the nodule unless biplane fluoroscopy is available. CT fluoroscopy combines the advantages of the real-time display of conventional fluoroscopy with a three-dimensional display format. CT FLUOROSCOPY TO ASSIST TBNA: PRELIMINARY CLINICAL RESULTS A single case report describing the use of CT fluoroscopy to assist TBNA has been published3I;however, we have performed over 20 cases to date. In approximately two thirds, the biopsy target was mediastinal lymphadenopathy and in one third the target was a lung nodule or consolidation. Diagnoses for mediastinal lesions have included metastasis, small cell carcinoma, and non-small cell carcinoma (Fig. 14). In several patients, a benign or nonspecific diagnosis was confirmed surgically or on clinical follow-up. Our preliminary results suggest an
accuracy of CT fluoroscopy-assisted TBNA of 70% to 80% in this selected group of patients. The total room time has not been documented precisely but is approximately 1 hour. The average time from first to last use of the CT scanner is about 45 minutes. The average duration of use of CT fluoroscopy is about 200 seconds. We have identified several factors that may have led to failure to diagnose the cause of mediastinal lymphadenopathy by TBNA. In most cases, the target lymph nodes were only slightly enlarged (1 to 2 cm) and constitute a subset that is known to be difficult to diagnose by TBNA. Several of the patients had undergone previous TBNA using conventional fluoroscopic guidance with indeterminate results, so that obtaining a specific diagnosis was probably more difficult than in a typical population referred for bronchoscopy. Technical issues also play a role. In one instance, the CT fluoroscopic image showed that the needle length was insufficient to reach the target node. In another patient, sampling error occurred because lymphocytes only were found in a right hilar mass by TBNA, but at surgery an adenocarcinoma of lung was diagnosed. CT fluoroscopy proved effective at localizing the site of the bronchoscopic needle in relation to the target lymph node. Not sur-
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Figure 15. A 62-year-old woman with a lingular mass. A, CT scan filmed on lung windows reveals a central lingular mass, (arrow). B, CT fluoroscopic image shows the bronchoscopic needle apparently within the mass (arrow). No diagnostic material was obtained. At surgery, the lesion proved to be a metastatic spindle cell sarcoma. (From White CS: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209218, 1999; with permission.)
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Figure 16. A 41-year-old man with a draining sinus tract. CT fluoroscopic image acquired immediately after contrast injection shows contrast pooling adjacent to the left lateral ribs (arrow). No fistula was identified.
prisingly, a 19-gauge aspiration needle was more easily visualized than a 21-gauge needle, although both were readily visible. The bronchoscope created substantial artifact but did not interfere with identification of the needle position. The bronchoscopic artifact was usually not present when subcarinal nodes were aspirated because the needle and bronchoscope were not in the same imaging plane. CT fluoroscopy was especially useful in demonstrating malposition of the needle including placement in the aorta and lung. Several of the lung nodules or areas of consolidation for which we have attempted CT fluoroscopic-guided TBNA have been rather small. Our subjective impression is that the procedure is more likely to be successful if a bronchus extends into the nodule. If no feeding bronchus is present, the needle, as visualized by CT fluoroscopy, is difficult to bring in proximity to the nodule. Our findings tend to confirm the validity of the bronchus sign, as described by Naidich et a1.I2 They reported that the finding of a bronchus extending into a lung nodule as visualized on CT was associated with a significantly higher rate (60%) of achieving a tissue diagnosis by bronchoscopy than if the sign was absent (30%). Moreover, among seven patients with thin section imaging, only one patient (14%) without a bron-
chus sign had a diagnostic bronchoscopic bio p s ~The . ~ bronchus ~ sign, however, does not guarantee success. In one central parenchymal lesion that was approached using CT fluoroscopic guidance for TBNA, no endobronchial component was observed and the procedure was not diagnostic (Fig. 15). Malposition of the biopsy needle in the lung is easily observed on CT fluoroscopy. Often, the needle is identified in the wrong subsegment and CT fluoroscopy is valuable to direct repositioning. Complications, such as pneumothorax and hemorrhage in the lung, are detected rapidly. Our experience suggests that CT fluoroscopy has the potential to increase the diagnostic accuracy of inexperienced bronchoscopists by showing the precise location of the bronchoscopic needle in relation to the target lesion. By increasing confidence in needle placement, it may also encourage bronchoscopists to use a large-gauge needle when necessary. MISCELLANEOUS APPLICATIONS The real-time guidance capability of CT fluoroscopy can be applied to other interventional thoracic procedures that may be cum-
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bersome to perform with nonfluoroscopic CT. We have used CT fluoroscopy to evaluate the extent of a sinus tract in a patient with a draining cutaneous wound by observing the distribution of injected contrast in real time (Fig. 16). Another potential application of CT fluoroscopy is to aid the bronchoscopist in locating the source of a persistent bronchopleural fistula by tracking sequential segmental injections of contrast material and visualizing a connection to the pleural space. References 1. Bartlett JG, Finegold SM Anaerobic infections of the lung and pleural space. Am Rev Respir Dis 1105677, 1974 2. Dahlgren S, Nordenstrom B: Transthoracic Needle Biopsy. Stockholm, Almqvist and Wiksell, 1966, pp 1-32 3. Daly 8, Templeton PA: Real-time CT fluoroscopy: Evolution of an interventional tool. Radiology 211~309-315,1999 4. Greenfield AL, Steiner RM, Liu JE3: Sonographic guidance for the localization of peripheral pulmonary nodules during thoracoscopy. AJR Am J Roentgenol 168:1057-1060, 1997 5. Hashim SW, Baue AW, Geha A S The role of mediastinoscopy and mediastinotomy in lung cancer. Clin Chest Med 3:353-359, 1982 6. Hsu WH, Chiang CD, Hsu JY, et al: Ultrasoundguided fine-needle aspiration biopsy of lung cancers. J Clin Ultrasound 24:225-233, 1996 7. Katada K, Kato R, Anno H, et al: Guidance with real-time CT fluoroscopy: Early clinical experience. Radiology 200:851-856, 1996 8. Klein J, Schultz S: Interventional chest radiology. Curr Frob1 Diagn Radiol 21:219-268, 1992 9 Li H, Boiselle Pkf, Shepard JO, et a1:'Diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of the lung: Comparison of small and large pulmonary nodules. AJR Am J Roentgenol 167105-109, 1996 10. Light RW, Girrard WM, Jenkinson SG, et al: Parapneumonic effusions. Am J Med 69507-512, 1980 11. Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998 12. Naidich DP, Sussman R, Kutcher WL, et al: Solitary pulmonary nodules: CT-bronchoscopic correlation. Chest 93:595-598, 1988 13. OMoore PV, Mueller PR, Simeone JF, et al: Sonographic guidance in diagnostic and therapeutic interventions in the pleural space. AJR Am J Roentgenol 149~1-5,1987
14. Patz EF, Goodman PC, Erasmus TI: Percutaneous drainage of pleural collections. J-Thorac Imaging 13:8>92, 1998 15. Rong F, Cui 8: CT scan directed transbronchial needle aspiration biopsy for mediastinal nodes. Chest 114:36-39, 1998 16. Shannon JJ, Bude RO, Orens JB, et al: Endoscopic ultrasound-guided needle aspiration of mediastinal adenopathy. Am J Respir Crit Care Med 153314241430, 1996 17. Silverman SG, Mueller PR, Saini S, et al: Thoracic empyema: Management with image-guided catheter drainage. Radiology 1 6 9 5 9 , 1988 18. Stavas J, v d o n n e n b e r g E, Casola G, et al: Percutaneous drainage of infected and noninfected thoracic fluid collections. J Thorac Imaging 280-87, 1987 19. Tartle DA, l'otts DE, Sahn S A The incidence and clinical correlates of parapneumonic effusions in pneumococcal pneumonia. Chest 74:17G173, 1978 20. Tarver RD, Conces DJ: Interventional chest radiology. Radiol Clin North Am 32689-709, 1994 21. Templeton PA, Foumier RS, Meyer CA, et al: Lung nodules 1.5 cm or smaller in size: CT biopsy success using CT fluoroscopy. Radiology 205(P):174, 1997 22. Ulmer JL, Choplin RH, Reed JC: Image-guided catheter drainage of the infected pleural space. J Thorac Imaging 6:65-73, 1991 23. Ulrik Knudsen D, Moller Nielsen S, Hariri J, et al: Ultrasonographically guided fine-needle aspiration biopsy of intrathoracic tumors. Acta Radiol 37327331, 1996 24. Utz JP, Pate1 AM, Edell ES: The role of transcarinal needle aspiration in the staging of bronchoscopic carcinoma. Chest 1041012-1016, 1993 25. Van Sonnenberg E, Casola G, Ho M, et al: Difficult thoracic lesions: CT guided biopsy experience in 150 cases. Radiology 167457461, 1988 26. Van Sonnenberg E, Wittich GR, Goodacre BW, et al: Percutaneous drainage of thoracic collections. J Thorac Imaging 13:74-82, 1998 27. Wang Kp: Transbronchial needle aspiration and percutaneous needle aspiration for staging and diagnosis of lung cancer. Clin Chest Med 16:53.5552, 1995 28. Weisbrod G L Transthoracic needle biopsy. World J Surg 1770.5711, 1993 29. Westcott JL: Direct percutaneous needle aspiration of localized pulmonary lesions: Results in 422 patients. Radiology 137:31-35, 1980 30. Westcott JL, Rao NR, Colley DF: Transthoracic needle biopsy of small pulmonary nodules. Radiology 20297-103, 1997 31. White CS, Templeton PA, Hasday JD:CT-assisted transbronchial needle aspiration: Usefulness of CT fluoroscopy. AJR Am J Roentgenol 169:393-394, 1997 32. Yang PC, Luh KT, Sheu JC, et al: Peripheral pulmonary lesions: Ultrasonography and ultrasonically guided aspiration biopsy. Radiology 155:451-456, 1985
Address reprint requests to Charles S . White, MD Department of Diagnostic Radiology University of Maryland School of Medicine 22 South Greene Street Baltimore, MD 21201 e-mail: [email protected]
INTERVENTIONAL CHEST RADIOLOGY
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CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES Charles S. White, MD, Cristopher A. Meyer, MD, and Philip A. Templeton, MD
The recent introduction of CT continuous imaging, also called real-time CT and CT fluoroscopy, has improved the ease of performing interventional thoracic procedures. This article discusses the use of CT fluoroscopy to facilitate percutaneous needle aspiration biopsy and pleural drainage in relation to established techniques. We also describe our experience in applying CT fluoroscopy for a newer application, guidance of transbronchial bronchoscopic biopsy. PERCUTANEOUS NEEDLE ASPIRATION: CURRENT IMAGE GUIDANCE TECHNIQUES
Percutaneous needle aspiration was first reported in the late 18OOs, and the imageguided approach for sampling of lung nodules came into widespread use in the 1960s.2 Conventional fluoroscopy was initially used and permits direct visualization of the nodule during sampling. Biplane fluoroscopy allows improved ease of biopsy. Based on several studies, the accuracy of fluoroscopically guided biopsy is 61% to 97%.2' Fluoroscopy remains the guidance technique of choice in many practices, but is not suitable for every lesion. Small nodules may be difficult or impossible to identify. The ac-
curacy for biopsy of lesions greater than 2 cm is 80%, as compared with 60% for lesions less than 1 cm. Lesions smaller than 1 cm may be difficult to visualize and low-density or indistinct nodules often are difficult to detect. Another important limitation of conventional fluoroscopy is that some lesions may be superimposed on and not separable from normal thoracic structures, such as the hila and mediastinum. In some instances, biopsy using fluoroscopic guidance may not be advisable if the nodule is adjacent to a major cardiovascular structure, such as the aorta.25 Several investigators have reported thoracic biopsy results using ultrasound guidance.6,23* 32 Advantages of ultrasound include real-time imaging and lack of ionizing radiation. Sonography is limited by attenuation of the beam as it traverses air-filled lung, however, obscuring nodules that are deep in the lung. Intraoperative ultrasound has been used to localize pulmonary nodules during thoracoscopy because the lung is a i r l e s ~U1.~ trasound is best used to facilitate biopsy of pulmonary nodules that abut the pleural surface. Standard CT is the most commonly used technique for lung biopsy and is safe and accurate. Sensitivity exceeds 90% for malignant lesions, although it is somewhat lower for benign nodules.29For small lung nodules
From the Department of Diagnostic Radiology, University of Maryland School of Medicine, Baltimore, Maryland (CSW, CAM, PAT); currently, the Department of Diagnostic Radiology, University of Cincinnati Medical Center, Cincinnati, Ohio (CAM)
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(those less than or equal to 1.5 cm), CT is the optimal technique. Two studies have reported biopsy success rates of 74% and 93%, respec30 Both studies emtively, for small nod~les.~, phasized the advantage of CT in guiding the approach of the needle toward the nodule and to document localization of the needle tip within the nodule. Standard CT has several limitations that are a consequence of the lack of real-time visualization. It may take several attempts to localize the nodule and achieve proper angulation of the needle toward the nodule. With each adjustment, the biopsy team must leave the scanning room while the new needle location is confirmed. Respiratory motion may alter the relationship of ribs and other structures with respect to the nodule and compensation can be difficult in the absence of realtime observation. Moreover, the actual sampling of the lesion is not observed directly to ensure that the needle tip is within the nodule. CT FLUOROSCOPY FOR LUNG NODULES: EQUIPMENT The technical specifications of the continuous-imaging (fluoroscopic)CT scanner are de-
scribed elsewhere. A brief summary is provided here.3* Like most standard CT scanners, fluoroscopic CT uses slip-ring (spiral) technology. The real-time visualization is achieved in part by the use of a rapid array processor and fast reconstruction algorithm that permits rapid image reconstruction and display. An in-room control panel and monitor permits the radiologist, wearing standard fluoroscopic radiation protection, to perform and view CT images while remaining in the scanning room (Figs. 1 and 2). The control panel allows in-room activation of the laser light and scanner and manipulation of table position and height and gantry angle. Movement of the table is achieved with either a joystick on the control panel or a manual sliding mode, which allows the radiologist to slide the table freely. The monitor and control panels are freestanding and can be positioned optimally for each procedure. The radiologist can put sterile drapes on the control panel and the foot of the table and perform the entire procedure without assistance. Alternatively, an assistant can operate the monitor and table. A button on the control panel or a foot-pedal identical to that used for routine fluoroscopy is depressed to activate real-time imaging. The choice of needle is dependent on the
Figure 1. CT fluoroscopy suite demonstrates the integrated monitor, control panel and gantry. Note the sterile cover over the control panel that permits the radiologist to operate the CT fluoroscopy system and manipulate the catheter without compromising sterile technique. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998; with permission.)
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Figure 2. CT fluoroscopy control panel. The left joystick adjusts gantry angle and the right joystick controls table movement. Additional functions include: power, laserlight, localizer, table height, freehand sliding mode table position, and emergency weight-off switch. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:10971101, 1998; with permission.)
size and location of the lesion and amount of tissue required; the risk of complications (e.g., pneumothorax); and the preference of the operator. If the radiologist wishes to view the nodule while the needle is being advanced or during sampling, a modification of technique is often necessary to avoid exposure of the hand holding the needle to the primary radiation beam. One approach to overcome this problem is to use a needle-holder during biopsy. One device that has been designed is an acrylic resin screw lock device with a handle that projects perpendicular to the needle shaft. The operator advances the needle with the handle allowing the hand to stay outside of the primary beam. A simpler method of avoiding the primary beam is to grasp and direct the needle with a surgical clamp while performing the biopsy in real time. CT FLUOROSCOPY OF LUNG NODULES: OPERATOR TECHNIQUE
CT fluoroscopic biopsies can be performed using either a real-time or an interrupted realtime operator technique. The real-time technique uses direct visualization by CT fluo-
roscopy while the needle is being advanced and during biopsy of the nodule itself. A perpendicular needle-holding device is necessary to avoid direct exposure of the operator’s hand to the primary radiation beam. Katada et a17 have described three variations of the real-time approach: (1) breath-hold method, (2) couch-sliding technique, and (3) controlled-respiration technique. The breath-hold method is simplest and is useful for biopsy of lesions in the upper part of the lung. The table remains stationary, the patient suspends respiration, and the nodule is sampled. The couch-top sliding method is valuable if the lesion has shifted out of the imaging plane because of patient movement. This technique consists of moving the couch-top longitudinally to locate both the lesion and needle tip in the same imaging plane, facilitating puncture of the needle. The controlled-respiration technique was found to be valuable in patients with lesions near the diaphragm. With this technique, the patient is instructed to expire fully before scanning. After scanning is initiated, the patient inhales slowly. When the maximal diameter of the lesion comes into the imaging plane, the patient suspends respiration and the biopsy is per-
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formed. Advantages of the real-time technique include the ability to document needle location within the nodule as it is being aspirated.7Movement of the needle into the nodule (puncturing) or pushing away of the nodule (balloting) by the needle can be observed. The second basic biopsy technique has been termed the interrupted real-time technique. With the interrupted real-time technique, needle advancement and nodule biopsy are not directly visualized but are rapidly confirmed after each advance of the needle using a short pulse of fluoroscopy, often without removing the patient from the gantry. When the needle tip is clearly identified within the nodule, aspiration is done blindly or using direct visualization. Advantages of the interrupted real-time technique as compared with the real-time technique described previously include the increased distance of the operator from the primary beam, reducing exposure from radiation and eliminating the need for a needle holder." The improved tactile sensation provided by direct contact with the biopsy needle during aspiration is advantageous. A further advantage is that more complex biopsy techniques, such as a coaxial approach, or an automated biopsy device (gun), can more easily be used in conjunction with the interrupted real-time method. A potential disadvantage of the use of the interrupted method is that visualization of complications of the procedure might be delayed. This delay is minimal, however, as compared with conventional CT. CT FLUOROSCOPY TO GUIDE NEEDLE BIOPSY EARLY CLINICAL RESULTS
Reports of clinical experience with the use of CT fluoroscopy to guide percutaneous needle biopsy are limited. In the study of Katada et a1,7 results of 60 CT fluoroscopic procedures were reported in 57 patients, including 36 with CT-guided intrathoracic procedures. Among thoracic procedures, the target nodule was punctured on the first attempt in 83% of patients and the average number of passes for all nodules was 1.3. Diagnostic specimens were obtained in 32 (97%) of the 33 patients who underwent lung biopsy and included 17 malignant and 15 benign lesions. In a single 7 x 10 mm lesion, the needle tip was visualized in the nodule but there was insufficient
tissue for diagnosis. Mean time for the procedures was 54 minutes (range, 24 to 139 mi,nutes). An average of 74 seconds of CT fluoroscopy time was used for each puncture. There were 17 (47%) complications among the 36 thoracic procedures, including one episode of hemoptysis and 16 pneumothoraces. Three pneumothoraces were treated with aspiration of pleural air and two required placement of a chest tube. The authors concluded that the real-time capability of the CT fluoroscopy permitted reduction in the number of needle punctures required to do the biopsy and provided substantial overall advantages over standard CT. Our preliminary experience using CT fluoroscopy to assist in the biopsy of small pulmonary nodules is also promising.21We studied 17 patients with nodules of 1.5 cm or less. In most cases, we used a coaxial biopsy technique and the interrupted real-time CT fluoroscopy method (Figs. 3 and 4). As on standard CT, the needle tip was routinely identified by its characteristic low-density artifact (Figs. 5 and 6). We obtained diagnostic tissue in 16 (94%) of the 17 lesions, including 11 malignant and 5 benign nodules. The nondiagnostic biopsy occurred in a small, deep lesion in which the procedure was discontinued after a single pass. At surgery, this lesion proved to be a non-small cell carcinoma. The mean lesion depth in our study was 7 cm. The mean number of passes was 2.5. For these small lesions, the mean fluoroscopic time for each puncture was 103 seconds. Image quality was good using 30 mA and 120 kilovolt (peak). Average room time was 91.5 minutes. Nine patients (53%)in our series developed complications, including one with hemoptysis and eight with pneumothorax. Two patients with pneumothoraces required chest tube drainage. The rate of success and complications in the two series is ~irnilar.~,It is likely that the increased number of punctures required in our series is because of the smaller size of the nodules. The longer room time in our series may be due to the small size of the nodules and other factors, such as extra time needed for supervision of a resident or fellow. In addition to use of CT fluoroscopy to assist interventional procedures in the lung, we have found CT fluoroscopy guidance Valuable to obtain biopsies of lesions in the pleura and paraspinal region, mediastinum, and chest wall (Figs. 6 and 7). For these areas,
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Figure 3. A 56-year-old man with a 1.5-cm left upper lobe nodule. Image from a CT fluoroscopy segment shows the needle traversing an area of bullous disease (arrow) posterior to the nodule. (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
Figure 4. A 50-year-old woman with an irregular small density in the periphery of the left upper lobe. The needle is directed toward the lateral margin of the lesion. Biopsy showed adenocarcinoma of the lung. (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209218, 1999; with permission.)
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Figure 5. A 56-year-old woman with a subpleural lesion in the left lower lobe. Note the low attenuation artifact that arises from the tip of needle (arrowhead) indicating its position within the tumor. Biopsy revealed adenocarcinoma of the lung. (From White CS, et al: CT Fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
the real-time capability may permit the operator to avoid traversing lung parenchyma. Although it is a subjective impression that CT fluoroscopy allows biopsies to be obtained more rapidly it is important to recognize that no study has directly compared the duration of procedures done with standard CT and CT fluoroscopy to ascertain if there is a decrease in procedure time with the latter. Likewise, other purported advantages of CT fluoroscopic guidance have not been compared directly with standard CT. CT FLUOROSCOPY FOR GUIDING PERCUTANEOUS BIOPSY SUMMARY
As compared with techniques other than CT, CT fluoroscopy shares with standard CT the advantages of excellent spatial resolution, a wide field of view, optimal imaging of airfilled structures, limited operator dependence for obtaining images of good quality, and the ability easily to place the biopsy needle in the imaging plane. Standard CT is impeded by the necessity to acquire a series of images after each movement of the biopsy needle,
however, requiring the radiologist to exit the scanning room for each acquisition. Further time elapses as the images are reconstructed and displayed and any patient movement may change the needle position in relation to anatomic landmarks. CT fluoroscopy obviates leaving the scanning room because images are available in the room and are observed in real time. In our study, we estimated that the use of CT fluoroscopy resulted in a decrease of 2 to 4 minutes per needle adjustment as compared with standard CTJ1 Several potential advantages of the realtime capability of CT fluoroscopy have been described. These include the ability visually to time the biopsy puncture more easily with the phase of respiration, avoiding ribs and other intervening structures. CT-fluoroscopic guidance may facilitate placement of the needle preferentially at the edge of the lesion, which is useful in masses with a necrotic center. If the real-time technique is used, the nodule may be seen to be pushed away (balloted) by the needle, indicating the need for a more rapid puncture technique. The real-time imaging afforded by CT fluoroscopy permits rapid diagnosis of complications. It is common to recognize hemorrhage around the nodule after biopsy and a needle track is often observed on withdrawal of the needle (Fig. 8). Few of these patients develop hemoptysis. Pneumothoraces are recognized quickly so that appropriate management can be instituted (Fig. 9). An important subjective advantage of CT fluoroscopy is the increased peace-of-mind that it provides for the radiologist. The short time interval between movement of the needle and knowledge of its location and any complications can substantially decrease stress related with the procedure. There are few disadvantages to the use of CT fluoroscopy for thoracic procedures. Concern has been raised about excessive radiation exposure that may occur in versions of CT fluoroscopy offered by certain vendors. In our experience, the radiation dose has been well within acceptable limits. CT FLUOROSCOPY USE IN ASSISTING INTRATHORACIC DRAINAGE PROCEDURES
Image-guided chest drainage procedures have become commonplace in the treatment of parapneumonic effusions; malignant effu-
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Figure 6. A 48-year-old man with a mass involving the upper thoracic vertebral body with paraspinal extension. A, CT fluoroscopic image shows the needle traversing the left transverse process and rib in an extraparenchymal course (arrow). €I, Subsequent image shows the needle tip in the left paraspinal mass, as indicated by the low attenuation artifact that emanates from it (arrowhead). (From White CS, et al: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209-218, 1999; with permission.)
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Figure 7. A 67-year-old man with multiple left pleural nodules. Image from a CT fluoroscopic segment demonstrates the needle within a pleural nodule. Biopsy showed sarcoidosis. (From White CS: CT Fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lntelventional Radiology 16:209-218, 1999, with permission.)
sions; pneumothoraces; and occasionally, mediastinal fluid collections. Image-assisted thoracic drainage of loculated pleural collections has a consistently higher success rate than blindly inserted thoracostomy tubes. Radiology drainage tubes are, in general, more easily positioned, smaller in caliber, and better tolerated by the patient.22Methods of imaging-guided insertion include fluoroscopy, ultrasound, and CT. These topics have been reviewed in detail recently.*,14,18, 20, 26
CHOICE OF IMAGING MODALITY
Many factors are involved in the selection of the appropriate imaging modality for drainage of intrathoracic collections.These include the characteristics of the thoracic collection, patient parameters, and the radiologist's specific modality expertise. Size, location, and contents of the collection are characteristics that should be considered when selecting the appropriate imaging modality. In general, large fluid collections and free-flowing collections are most easily and rapidly drained using ~ l t r a s o u n d . Ultra'~ sound is the modality of choice because it lacks ionizing radiation, is portable, and allows real-time visualization of needle and catheter placement. A free-flowing collection may be difficult or impossible to approach
with CT guidance because the fluid collection tends to move to a dependent position in the chest. Although homogeneous collections are easily localized and drained sonographically, complex fluid collections and air cannot be distinguished from underlying aerated lung parenchyma and may require CT guidance.17 The location of the fluid collection helps to determine the choice of modality. The radiologist must ensure that there is adequate visualization of intervening vessels, particularly the internal mammary and mediastinal great vessels, which may be easier using CT. Finally, patients who are unable to suspend respiration present a challenge to the placement of large drainage catheters. Using CT fluoroscopy the expected route of access to the fluid collection can be visualized throughout the respiratory cycle. This allows the radiologist to coordinate needle placement with an adequate window to avoid damage to intervening structures." PLEURAL DRAINAGE
In our experience, the most common request for pleural drainage is to treat parapneumonic effusion or empyema." Up to 50% of patients with pneumonia have accompanying pleural fluid.l, lo, l9 The choice of treatment depends on the fluid characteristics (i.e., transudate versus exudate). In general, a tran-
CT FLUOROSCOPY FOR THORACIC INTERVENTIONAL PROCEDURES
Figure 8. A 65-year-old woman with a right lobe nodule. A, CT shows a smoothly marginated nodule medially in the right lower lobe (arrow). 6,Image from a CT fluoroscopic segment shows the needle adjacent to the nodule. Note the hemorrhage that has occurred along the needle track and around the nodule from an earlier biopsy pass (arrows). The second pass revealed non-small-cell carcinoma.
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Figure 9. A 61-year-old man after successful left upper lobe biopsy. A, CT fluoroscopy image obtained moments after the needle was withdrawn shows a moderate anterior pneumothorax. B, CT fluoroscopic image after placement of a pleural drainage catheter shows appropriate location of the catheter and minimal residual pneumothorax. (From White CS: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:20%218, 1999; with permission.)
sudate or simple parapneumonic effusion responds to the antibiotic therapy; most drainage catheter placements are reserved for exudative effusions, either infectious, inflammatory, or neoplastic. Techniques for pleural drainage using CT fluoroscopy are similar to those for standard CT. The patient is scanned using the real-time capabilities of the CT scanner to plan the site of access to the pleural collection for optimal drainage and patient comfort. Care should be taken to identify a route that avoids the intercostal artery, vein, and nerve that run on the undersurface of each rib. The patient is
prepared and draped in sterile fashion and a sterile cover is placed over the control panel. The procedure may then be performed either in real time by watching the Seldinger needle or trocar advance into the pleural fluid collection or with an interrupted real-time technique. We have generally used the latter technique because it minimizes exposure to the operator's hands. With this technique, the needle is advanced in a stepwise manner with short applications of fluoroscopic CT to confirm the needle and catheter path." The radiologist stays in the CT suite and initiates CT fluoroscopy by the control panel. The patient
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Figure 10. A 50-year-old man with leukemia and right focal pleural fluid collection after treatment of Nocardia pneumonia. A pigtail catheter was placed in this posterior fluid collection using a modified Seldinger technique. Following evacuation of 20 cc of brown purulent material, the patient's fever abated and he recovered uneventfully with antibiotics.
remains within the gantry throughout the process of needle placement for improved efficiency. Access to the pleural fluid may be accomplished using either a trocar or modified Seldinger technique. Generally, large pleural fluid collections that are not adjacent to critical vascular structures may be accessed using a single stick method with a 12F to 14F catheter. We prefer hydrogel-coated catheters for ease of traversing fascial planes." The stiffness of these catheters also prevents kinking once they are placed. We have had several instances in which a locked catheter that had been placed in an inflammatory fluid collection remained locked after thread release. We place only self-forming pigtail catheters in the pleural space. A modified-Seldinger technique should be used for technically challenging collections. In these patients, a 19-gauge Seldinger entry needle is placed into the thoracic collection under CT fluoroscopic guidance. Subsequently, a 0.038-in (0.097 cm) Bentsen guidewire is placed through the needle and coiled in the pleural collection. The tract is expanded with serial fascial dilators to 12F catheter. A 14F pigtail catheter is passed over the guidewire using the hollow stiffening stylet to keep the catheter straight. The stylet is fixed in position and the catheter is advanced off the stylet into the pleural collection. Dilatation and catheter placement are accom-
plished with the patient outside the CT gantry and without imaging observation. Subsequent documentation of catheter placement and, if necessary, manipulation are performed under direct CT fluoroscopic observation (Fig. 10). Complex fluid collections with loculation may require the placement of multiple drainage catheters or intrapleural fibrinolytics. MEDIASTINAL COLLECTIONS Mediastinal fluid collections and abscesses are uncommon but technically challenging to access and drain effectively. Mediastinal collections that may require drainage include postoperative abscesses, especially those following esophageal surgery (Fig. 11);infected mediastinal duplication cyst; lymphocele; Boerhaave's syndrome, or mediastinal pancreatic pseudocyst.26Image-guided mediastinal drainage is technically similar to pleural drainage procedures but care is necessary to avoid laceration of the internal mammary vessels, great veins, or arteries as the catheter is advanced. For this reason, CT fluoroscopy offers a substantial advantage over current imaging modalities because it permits realtime observation of the needle path." We have also used CT fluoroscopy to drain a loculated anterior pericardial collection while observing the relationship of the catheter to
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Figure 11. A 77-year-old man with mediastinal mucocele 2 years after an emergency esophagectorny for perforation. A, Initial CT fluoroscopy performed for placement of a 19-gauge Seldinger needle into the fluid collection. B,After guidewire placement and tract dilatation, a pigtail catheter is confirmed to be in the collection. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998; with permission.)
the right ventricle as the collection was drained (Fig. 12). PNEUMOTHORAX Thoracostomy tube placement is useful for a large, symptomatic, or enlarging pneumothorax. Radiologists may be required to place a chest tube after a transthoracic needle biopsy. We occasionally place small-bore thoracostomy tubes for loculated pneumothoraces in patients who have undergone lung volume reduction surgery, lung transplantation, or in
patients on a ventilator with the adult respiratory distress syndrome. Such patients may be at increased risk of intraparenchymal tube placement because of pleural adhesions. CT-guided pneumothorax drainage follows the same basic steps described for the drainage of pleural fluid collections. Smaller-bore chest tubes are usually effective (8F to 10F catheter) but a 12F to 14F catheter tube may be necessary for large pleural tears. Placement of pneumothorax tubes varies based on pneumothorax location and the patient’s functional status. Insertion of a catheter for an anterior pneumothorax is relatively
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Figure 12. A 42-year-old alcoholic man with poor cardiac output and a pericardial fluid collection. A, A 20-gauge angiocatheter needle (arrow) has been advanced into the collection parallel to the right ventricle under fluoroscopic guidance. B, The collection is smaller following aspiration. On real-time imaging, cardiac pulsation could be visualized deviating the needle, and the procedure was electively terminated.
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straightforward. CT fluoroscopy may be useful in guiding catheter placement in a complex, loculated pneumothorax." In one case, CT fluoroscopic assistance allowed us to place a drainage tube in a loculated major fissural pneumothorax by observing a small window along the su erolateral chest wall during the expiratory p ase of respiration (Fig. 13).
K
CT FLUOROSCOPY USE IN ASSISTING TRANSBRONCHIAL NEEDLE ASPIRATION
Transbronchial needle aspiration (TBNA) is useful to diagnose central parenchymal le-
sions and sample mediastinal nodes. Nodal status has important implications for the staging and prognosis of lung cancer. Although mediastinoscopy, mediastinotomy, and thoracoscopy are valuable techniques for mediastinal staging, TBNA with bronchoscopic guidance is frequently used to sample abnormal lymph nodes that are located near an airway?, 24, 27 Lymph nodes in the subcarinal and right and left paratracheal regions are most easily aspirated. One important limitation of TBNA as compared with surgical techniques is that the target node is not visible through the bronchoscope. The bronchoscopic needle may be advanced through the airway wall using
Figure 13. A 59-year-old man with shortness of breath and a loculated pneumothorax after lung volume reduction surgery. A modified Seldinger technique was used to access the major fissure through a 1-cm pleural window. A, CT fluoroscopic image with the 19gauge Seldinger needle accessing the major fissure, while avoiding adjacent lung parenchyma (arrow). 6,CT fluoroscopic image after decompression with an 8F catheter. The patient was symptomatically improved, although the pneumothorax is incompletely drained. Illustration continued on opposite page
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Figure 13 (Continued). C, CT fluoroscopic image after exchanging the 8F catheter for a 12F catheter with improved decompression. This tube was placed to 20 cm H,O Pleur-Evac suction. Note thrombus (T), which was present before imaging intervention. (From Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: Usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-I 101, 1998; with permission.)
landmarks identified on the preprocedure CT scan and distortions or bulges of the airway encountered during the procedure. Conventional fluoroscopy is often used to guide TBNA and improve the yield of the procedure. This technique is limited, however, by the overlap of structures in the mediastinum produced by the two-dimensional fluoroscopic display. In many instances the enlarged mediastinal lymph node is not distinguishable using conventional fluoroscopy. The inability of fluoroscopy to provide adequate visualization of the target lymph node has limited widespread use of TBNA. Moreover, it has fueled the perception that TBNA is difficult, potentially dangerous, and should be practiced only by experienced bronchoscopists. Most series have indicated that the technique is inferior to that of surgical series with sensitivity ranging from 37% to 90%.24,27 Many patients who might be candidates for bronchoscopically guided TBNA are referred for surgery. Sonographic assistance of TBNA, in which an ultrasound probe is inserted into the bronchoscope,16 is an alternative guidance technique that currently suffers from two limitations. First, the diagnostic quality of the sonographic images is variable; it may be difficult to distinguish lymph nodes from other anatomic structures. The technique is highly
operator dependent. Second, the ultrasound probe is passed through the same port that is used for the biopsy needle. The probe must be withdrawn and the bronchoscopic position maintained while the needle is inserted. Realtime visualization is not achieved. Standard CT can also be used to image the location of the bronchoscope within the airway in relation to the target lymph nodes.I5 Rong and CuilS reported 60% sensitivity in diagnosing mediastinal adenopathy by TBNA using standard CT guidance. Similar to its use for percutaneous needle biopsy, however, standard CT is cumbersome because a substantial time delay occurs while the appropriate slice position is found, the technologist prescribes the sequence and scans the patient, and image reconstruction occurs. While this occurs, the bronchoscope must be maintained in a constant position for several minutes. This sequence of events must be repeated for each adjustment of the bronchoscope. The ability of CT fluoroscopy to provide real-time imaging is valuable in guiding TBNA.31 Using CT fluoroscopy, each movement of the bronchoscope can be verified quickly on the in-room monitor. The bronchoscopic needle is visualized as it is planted in the airway to ensure that it is directed toward the intended biopsy site. Once the needle has been advanced, CT fluoroscopy is used to
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ensure that the needle is in the target lesion. Complications, such as pneumothorax or hemorrhage, are documented quickly. For lesions in which an initial nonsurgical approach is contemplated, the location of the abnormality determines whether percutaneous needle biopsy or TBNA is performed. Peripheral lesions, particularly those that are
in a subpleural location, are most easily sampled using a percutaneous technique. Central lesions and especially those in which a bronchus extends into the lesion, are optimally diagnosed using bronchoscopy with TBNA. Large central lesions are diagnosed routinely using bronchoscopy with or without fluoroscopic guidance, particularly if an endobron-
Figure 14. An 62-year-old man with a 3-cm right middle lobe nodule and mediastinal adenopathy. A, Enhanced CT scan obtained to stage the patient shows an enlarged subcarinal lymph node (arrow). B, CT fluoroscopic image of initial pass demonstrates the needle (arrow) to the right of the node. Only bronchial wall cells were obtained. Illustration continued on opposite page
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Figure 14 (Continued). C, CT fluoroscopic image reveals the bronchoscopic needle within the node (arrow). A diagnosis of non-small cell lung cancer was obtained.
chial component is present. Smaller lesions are more problematic and require fluoroscopic guidance. Conventional fluoroscopy, however, is limited in guiding TBNA if the lung nodule is very small. Moreover, it is often difficult to determine the anteroposterior relationship between the needle tip and the nodule unless biplane fluoroscopy is available. CT fluoroscopy combines the advantages of the real-time display of conventional fluoroscopy with a three-dimensional display format. CT FLUOROSCOPY TO ASSIST TBNA: PRELIMINARY CLINICAL RESULTS A single case report describing the use of CT fluoroscopy to assist TBNA has been published3I;however, we have performed over 20 cases to date. In approximately two thirds, the biopsy target was mediastinal lymphadenopathy and in one third the target was a lung nodule or consolidation. Diagnoses for mediastinal lesions have included metastasis, small cell carcinoma, and non-small cell carcinoma (Fig. 14). In several patients, a benign or nonspecific diagnosis was confirmed surgically or on clinical follow-up. Our preliminary results suggest an
accuracy of CT fluoroscopy-assisted TBNA of 70% to 80% in this selected group of patients. The total room time has not been documented precisely but is approximately 1 hour. The average time from first to last use of the CT scanner is about 45 minutes. The average duration of use of CT fluoroscopy is about 200 seconds. We have identified several factors that may have led to failure to diagnose the cause of mediastinal lymphadenopathy by TBNA. In most cases, the target lymph nodes were only slightly enlarged (1 to 2 cm) and constitute a subset that is known to be difficult to diagnose by TBNA. Several of the patients had undergone previous TBNA using conventional fluoroscopic guidance with indeterminate results, so that obtaining a specific diagnosis was probably more difficult than in a typical population referred for bronchoscopy. Technical issues also play a role. In one instance, the CT fluoroscopic image showed that the needle length was insufficient to reach the target node. In another patient, sampling error occurred because lymphocytes only were found in a right hilar mass by TBNA, but at surgery an adenocarcinoma of lung was diagnosed. CT fluoroscopy proved effective at localizing the site of the bronchoscopic needle in relation to the target lymph node. Not sur-
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Figure 15. A 62-year-old woman with a lingular mass. A, CT scan filmed on lung windows reveals a central lingular mass, (arrow). B, CT fluoroscopic image shows the bronchoscopic needle apparently within the mass (arrow). No diagnostic material was obtained. At surgery, the lesion proved to be a metastatic spindle cell sarcoma. (From White CS: CT fluoroscopy: Applications for biopsy of intrathoracic lesions. Seminars in lnterventional Radiology 16:209218, 1999; with permission.)
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Figure 16. A 41-year-old man with a draining sinus tract. CT fluoroscopic image acquired immediately after contrast injection shows contrast pooling adjacent to the left lateral ribs (arrow). No fistula was identified.
prisingly, a 19-gauge aspiration needle was more easily visualized than a 21-gauge needle, although both were readily visible. The bronchoscope created substantial artifact but did not interfere with identification of the needle position. The bronchoscopic artifact was usually not present when subcarinal nodes were aspirated because the needle and bronchoscope were not in the same imaging plane. CT fluoroscopy was especially useful in demonstrating malposition of the needle including placement in the aorta and lung. Several of the lung nodules or areas of consolidation for which we have attempted CT fluoroscopic-guided TBNA have been rather small. Our subjective impression is that the procedure is more likely to be successful if a bronchus extends into the nodule. If no feeding bronchus is present, the needle, as visualized by CT fluoroscopy, is difficult to bring in proximity to the nodule. Our findings tend to confirm the validity of the bronchus sign, as described by Naidich et a1.I2 They reported that the finding of a bronchus extending into a lung nodule as visualized on CT was associated with a significantly higher rate (60%) of achieving a tissue diagnosis by bronchoscopy than if the sign was absent (30%). Moreover, among seven patients with thin section imaging, only one patient (14%) without a bron-
chus sign had a diagnostic bronchoscopic bio p s ~The . ~ bronchus ~ sign, however, does not guarantee success. In one central parenchymal lesion that was approached using CT fluoroscopic guidance for TBNA, no endobronchial component was observed and the procedure was not diagnostic (Fig. 15). Malposition of the biopsy needle in the lung is easily observed on CT fluoroscopy. Often, the needle is identified in the wrong subsegment and CT fluoroscopy is valuable to direct repositioning. Complications, such as pneumothorax and hemorrhage in the lung, are detected rapidly. Our experience suggests that CT fluoroscopy has the potential to increase the diagnostic accuracy of inexperienced bronchoscopists by showing the precise location of the bronchoscopic needle in relation to the target lesion. By increasing confidence in needle placement, it may also encourage bronchoscopists to use a large-gauge needle when necessary. MISCELLANEOUS APPLICATIONS The real-time guidance capability of CT fluoroscopy can be applied to other interventional thoracic procedures that may be cum-
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bersome to perform with nonfluoroscopic CT. We have used CT fluoroscopy to evaluate the extent of a sinus tract in a patient with a draining cutaneous wound by observing the distribution of injected contrast in real time (Fig. 16). Another potential application of CT fluoroscopy is to aid the bronchoscopist in locating the source of a persistent bronchopleural fistula by tracking sequential segmental injections of contrast material and visualizing a connection to the pleural space. References 1. Bartlett JG, Finegold SM Anaerobic infections of the lung and pleural space. Am Rev Respir Dis 1105677, 1974 2. Dahlgren S, Nordenstrom B: Transthoracic Needle Biopsy. Stockholm, Almqvist and Wiksell, 1966, pp 1-32 3. Daly 8, Templeton PA: Real-time CT fluoroscopy: Evolution of an interventional tool. Radiology 211~309-315,1999 4. Greenfield AL, Steiner RM, Liu JE3: Sonographic guidance for the localization of peripheral pulmonary nodules during thoracoscopy. AJR Am J Roentgenol 168:1057-1060, 1997 5. Hashim SW, Baue AW, Geha A S The role of mediastinoscopy and mediastinotomy in lung cancer. Clin Chest Med 3:353-359, 1982 6. Hsu WH, Chiang CD, Hsu JY, et al: Ultrasoundguided fine-needle aspiration biopsy of lung cancers. J Clin Ultrasound 24:225-233, 1996 7. Katada K, Kato R, Anno H, et al: Guidance with real-time CT fluoroscopy: Early clinical experience. Radiology 200:851-856, 1996 8. Klein J, Schultz S: Interventional chest radiology. Curr Frob1 Diagn Radiol 21:219-268, 1992 9 Li H, Boiselle Pkf, Shepard JO, et a1:'Diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of the lung: Comparison of small and large pulmonary nodules. AJR Am J Roentgenol 167105-109, 1996 10. Light RW, Girrard WM, Jenkinson SG, et al: Parapneumonic effusions. Am J Med 69507-512, 1980 11. Meyer CA, White CS, Wu J, et al: Real-time CT fluoroscopy: usefulness in thoracic drainage. AJR Am J Roentgenol 171:1097-1101, 1998 12. Naidich DP, Sussman R, Kutcher WL, et al: Solitary pulmonary nodules: CT-bronchoscopic correlation. Chest 93:595-598, 1988 13. OMoore PV, Mueller PR, Simeone JF, et al: Sonographic guidance in diagnostic and therapeutic interventions in the pleural space. AJR Am J Roentgenol 149~1-5,1987
14. Patz EF, Goodman PC, Erasmus TI: Percutaneous drainage of pleural collections. J-Thorac Imaging 13:8>92, 1998 15. Rong F, Cui 8: CT scan directed transbronchial needle aspiration biopsy for mediastinal nodes. Chest 114:36-39, 1998 16. Shannon JJ, Bude RO, Orens JB, et al: Endoscopic ultrasound-guided needle aspiration of mediastinal adenopathy. Am J Respir Crit Care Med 153314241430, 1996 17. Silverman SG, Mueller PR, Saini S, et al: Thoracic empyema: Management with image-guided catheter drainage. Radiology 1 6 9 5 9 , 1988 18. Stavas J, v d o n n e n b e r g E, Casola G, et al: Percutaneous drainage of infected and noninfected thoracic fluid collections. J Thorac Imaging 280-87, 1987 19. Tartle DA, l'otts DE, Sahn S A The incidence and clinical correlates of parapneumonic effusions in pneumococcal pneumonia. Chest 74:17G173, 1978 20. Tarver RD, Conces DJ: Interventional chest radiology. Radiol Clin North Am 32689-709, 1994 21. Templeton PA, Foumier RS, Meyer CA, et al: Lung nodules 1.5 cm or smaller in size: CT biopsy success using CT fluoroscopy. Radiology 205(P):174, 1997 22. Ulmer JL, Choplin RH, Reed JC: Image-guided catheter drainage of the infected pleural space. J Thorac Imaging 6:65-73, 1991 23. Ulrik Knudsen D, Moller Nielsen S, Hariri J, et al: Ultrasonographically guided fine-needle aspiration biopsy of intrathoracic tumors. Acta Radiol 37327331, 1996 24. Utz JP, Pate1 AM, Edell ES: The role of transcarinal needle aspiration in the staging of bronchoscopic carcinoma. Chest 1041012-1016, 1993 25. Van Sonnenberg E, Casola G, Ho M, et al: Difficult thoracic lesions: CT guided biopsy experience in 150 cases. Radiology 167457461, 1988 26. Van Sonnenberg E, Wittich GR, Goodacre BW, et al: Percutaneous drainage of thoracic collections. J Thorac Imaging 13:74-82, 1998 27. Wang Kp: Transbronchial needle aspiration and percutaneous needle aspiration for staging and diagnosis of lung cancer. Clin Chest Med 16:53.5552, 1995 28. Weisbrod G L Transthoracic needle biopsy. World J Surg 1770.5711, 1993 29. Westcott JL: Direct percutaneous needle aspiration of localized pulmonary lesions: Results in 422 patients. Radiology 137:31-35, 1980 30. Westcott JL, Rao NR, Colley DF: Transthoracic needle biopsy of small pulmonary nodules. Radiology 20297-103, 1997 31. White CS, Templeton PA, Hasday JD:CT-assisted transbronchial needle aspiration: Usefulness of CT fluoroscopy. AJR Am J Roentgenol 169:393-394, 1997 32. Yang PC, Luh KT, Sheu JC, et al: Peripheral pulmonary lesions: Ultrasonography and ultrasonically guided aspiration biopsy. Radiology 155:451-456, 1985
Address reprint requests to Charles S . White, MD Department of Diagnostic Radiology University of Maryland School of Medicine 22 South Greene Street Baltimore, MD 21201 e-mail: [email protected]