Anal endosonography: A new application for high-frequency miniprobes

"4184 ANAL ENDOSONOGRAPHY: A NEW APPLICATION FOR I'HGHF R E Q U E N C Y MINIPROBES Jose M. Pontes, Aria T. Cadime, Alcides C. Catre, Gastroenterology Dept, Portuguese Institute of Oncology, Coimbra Portugal; Maria F. Lopes, Pediatric Surg Dept, Pediatric Hosp of Coimbra, Coimbra Portugal Background and Aims: Endosonography is currently considered the best method for assessing anal sphincter integrity and for local staging of anal cancer. Anal endosonography is usually performed with rigid probes or ~ith dedicated echoendoscopes. However, the relatively large diameter of these probes may produce anatomical distortion of the anal sphincters and may cause discomfort, particularly in paediatric patients. Moreover, image resolution is limited by the frequency range of these probes (6-12 MHz). Ultrasound miniprobes (MP) provide high-resolution images of the gastrointestinal wall. The aim of this study was to investigate the feasibility and effectiveness of MP in the evaluation of benign and malignant anal disorders. Methods: 360 ° radial scanning MP with 12 or 20 MHz transducers were used to perform anal endosonography in 22 patients, including 3 children. To ensure complete acoustic coupling with the anal wall, a waterfilled balloon catheter was placed over the MP, which was directly inserted in the anus without the assistance of a colonoscope. Examinations were performed with no intestinal preparation. In 8 adult volunteers with no anal disease, endesonography was performed to assess the ability of MP to image the anatomy of the anal canal. Indications for endesonography in the remaining patients were i) anal incontinence (obstetric trauma-7 cases, complications of ano-rectal surgery-2 cases), ii) staging of anal cancer (3 cases) and iii) follow up after radiotherapy for anal cancer (2 cases). Results: Patient tolerance was excellent. Paediatric patients did not require any sedation. MP endosonegraphy provided high-resolution images of the internal (IAS) and external (EAS) anal sphincters. Complete imaging of these sphincters could be achieved in all cases, but only by using the balloon sheath slightly fiUed with water. In assessing anal incontinence, MP endosonography demonstrated IAS defects (3 cases) and combined IAS :rod EAS defects (2 cases)[accuracy=100%]. MP correctly staged 2 cases of anal carcinoma, but in one case staging was not possible because of insufficient ultrasound penetration. In follow up after radiotherapy for anal cancer, MP showed no tumor recurrence. Conclusions: Our preliminary results suggest that MP endosonography is feasible and effective in assessing anal disorders. These probes may be especially useful in paediatric patients because of their small diameter. Further studies are needed to define the potential role and cost/effectiveness of MP in anal endosonography.

"4185 EUS GUIDED F I N E NEEDLE ASPIRATION CYTOLOGY AND TUMOR MARKER ANALYSIS OF PANCREATIC DUCTAL FLUID DIFFERENTIATES BETWEEN IPMT AND CHRONIC PANCREATITIS. Brenna C. Bounds, William R. Brugge, MA Gen Hesp, Boston, MA BACKGROUND: Intraductal papillary mucinous tumors (IPMT) represent premalignant or malignant lesions of the pancreas and are difficult to diflerentiate from chronic pancreatitis (CP) in patients with diffusely dilated pancreatic ducts and side branches. We compared a series of patients with IPMT, IPMT with malignancy, or CP who underwent EUS guided fine needle aspiration (FNA) of a dilated main pancreatic duct (PD) or side branch, to determine indicators that would permit segregation of these three entities based on cytology and tumor markers. METHODS: A consecutive series of 15 patients underwent EUS guided FNA of a dilated main PD or side branch. Fluid aspirates were sent for cytologic and tumor marker analysis (CEA and CA 19-9). Diagnostic histology obtained at the time of surgery was used as the gold standard in all cases. RESULTS: Sensitivity tbr cytologic detection of IPMT or IPMT with malignancy was 609'0 and 20% respectively with a negative predictive value of 55%. Sensitivity of cytology for detection of CP (based on an inflammatory aspirate) was 80% with a specificity of 70% and a positive predictive value of 57%. Mean CEA levels were significantly higher in IPMT than in CP (*p<0.01). Additionally, the ratio of CEA/CA 19-9 reliably distinguished CP from IPMT (+p<0.01). Interpretation of mean CA 19-9 levels did not reach statistical significance. No distinction could be made between IPMT and IPMT with malignancy

VOLUME 53, NO. 5, 2001

using either of the tumor marker analyzed or a ratio of the two, although a higher mean CEA and CA 19-9 was present in the population with malignant IPMT. CONCLUSIONS: Pancreatic duct]cyst fluid CEA and a ratio of CEA]CA19-9 appear to be useful in differentiating IPMT from chronic pancreatitis in patients with a diffusely dilated PD. Tumor MarkerAnalysisof PancreaticOuctalFluid

IPMT total (10)

Non.malignant(5) Malignant(5) CP (5)

Mean CEA

Mean CA 19-9

Mean CEA/CA19.9

'573 _+461 397 .+422 784 ...~455

40107 255230 12984 Y:7549 67230 2:70478

1"0.227+511 0.063 ~068 0.391 Y=717

• 31 _+14

216942 ~325476

1.0.00028~.0057

"4186 PANCREATIC CORE BIOPSIES CAN BE OBTAINED WITH EUSGUIDED 19G NEEDLE SYSTEMS Kevin McGrath, Cynthia Guy, Gall Robuck-Mangum, Jorge Obando, Christa Allen, Ted Pappas, Paul S. Jowell, Duke Univ Medical Ctr, Durham, NC Background: A pancreatic core biopsy would be advantageous in evaluating patients with suspected chronic pancreatitis in order to make a definitive diagnosis. We therefore tested 2 EUS-guided 19g needle systems to determine the reliability of obtaining core pancreatic samples. Methods: Two experienced endosonographers performed EUS-guided pancreatic biopsies using a linear echoendoscope (Pentax FG-36) in 5 mid-sized (70 lb) pigs. After general anesthesia, an overtube was placed to facilitate esophageal intubation. The pancreatic body/tail was located and using a transgastric approach, 20 pancreatic biopsies were performed in each pig as follows: 5 with the 19g Medi-Globe (MG) needle with suction, 5 without suction and 5 with the 19g Wilson-Cook (WC) needle with suction, 5 without suction. A biopsy was defined as one pass where the needle was moved to and fro 10 times. 10 cc of suction were used for each needle system. New needles were used for each pig. Once obtained, the pancreatic sample was expressed onto filter paper using the stylet only, and then placed in a separate formalin jar for processing. Pigs were euthanized immediately following the procedure. A single pathologist evaluated all samples (n=100) in a blinded fashion to assess for the presence of pancreatic histology (core sample). Results: Pancreatic core samples were only obtained when the biopsy was performed with suction. The WC needle obtained a core sample in 60% of samples. The MG needle obtained a core sample in 20% of samples (Table 1). Conclusion: Core pancreatic samples for histologic interpretation can be obtained using EUS-guided 19g needle systems in the porcine model. The WC needle was more reliable than the MG needle in obtaining a pancreatic core sample. The biopsy should be performed using standard suction. Subjectively, the WC needle was easier to visualize and was more operator-friendly. Supported by Pentax, Wilson-Cook and an ACG Research Grant Table 1 Core sample per 19g NeedleSystem Wilson-Cook Medi-Globe

Suction No Suction

15/25 (60%)

5125 (20%)

0•25 {0%)

0/25 (0%)

GASTROINTESTINAL ENDOSCOPY

AB163