CT and MR appearances of surgical packing materials

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CLINICAL RADIOLOGY

MAGNETIC RESONANCE ANGIOGRAPHY OF THE DISTAL LOWER EXTREMITY V. G. McDERMOTT, T. J. MEAKEM, J. P. CARPENTER, R. A. BAUM, A. H. STOLPEN and M. D. SCHNALL

Neurofibromatosis is an important and relatively common condition. It is important that radiologists are familiar with the range of findings, both on plain film and cross-sectional studies.

Hospital of University of Pennsylvania, Philadelphia, PA, USA Introduction: Magnetic resonance angiography (MRA) has been reported to demonstrate peripheral arteries not demonstrated by conventional angiography. Previous studies have not addressed arterial patency in the foot, which is important to prevent distal amputation. Design: Patients were drawn from a prospective study of MRA in the investigation of peripheral vascular disease. A patient was included if MRA down to and including the plantar arch was performed. Pre or intraoperative angiographic correlation was available in all cases. Subjects and Methods: 31 patients underwent peripheral MRA (bilateral in three cases), including the foot. 2D time-of-fright MRA (TR 33ms/TE 7.7ms/inferior saturation band) was performed with 16cm field of view. Results: In 24 limbs MRA was compared to conventional angiography. MRA showed more patent run-off vessel segments (119) than angiography (110). In 10 limbs MRA was compared to intraoperative angiography and showed a sensitivity of 92% for the detection of patent vessel segments. Pitfalls in the detection of patent vessel included in-plane flow and stair-step artifact. Conclusions: MRA is sensitive for the detection of patent arteries in the foot but artifacts may cause over diagnosis of focal stenoses or occlusions.

ENDORECTAL COIL MRI OF PROSTATIC CYSTS V. G. McDERMOTT, T. J. MEAKEM, A. H. STOLPEN and M. D. SCHNALL

Hospital of University of Pennsylvania, Philadelphia, PA, USA

RELATIONSHIP BETWEEN ULTRASONIC COLONIC THICKENING AND PANCREATIC ENZYMES IN CHILDREN WITH CYSTIC FIBROSIS E. MacSWEENEY, P. J. OADES, R. M. BUCHDAHL, M. PHELAN and A. BUSH

X-ray Department, Chelsea and Westminster Hospital, London Introduction: Fibrotic strictures of the colon in children with CF have recently been described and may be linked to the use of high strength pancreatin preparations. Design: Cross-sectional study, to determine the prevalence of US abnormalities in 99 children with CF and to determine relationship between abnormalities, treatments and patient characteristics. Subjects and Method: US scans were performed by a radiologist who was blinded to patient treatments. Healthy age, sex matched controls were included for comparison. Peristalsis was graded subjectivdy and measurements of colonic wall thickness were made. Results: Multiple logistic regression revealed that the risk of having a thickened bowel was 4 fold higher (95%/0 CI01.35 to 11.7; p = 0.03) in patients on high strength pancreatin preparations. Age, sex and genotype did not add extra risk. The probability of colonic thickening = 33.4% , for high strength enzymes. Significant correlation between the mean daily units of protease (PhEur) per Kg body weight and the maximum thickness of the ascending colon (Spearman's rank correlation coefficient; = 0.45; p < 0.001). Conclusion: High strength pancreatin preparations have been shown by ultrasound to be associated with colonic thickening. The technique may be used to monitor these children.

Introduction: The radiological diagnosis of periprostatic cysts depends on adequate demonstration of the relationship of the cyst to the ejaculatory apparatus. Endorectal coil MRI produces high resolution images of the prostate and periprostatic tissues, and may be the modality of choice in the investigation of these lesions. Design: Retrospective review of all endorectal coil MRI exams performed over a four year period. Subject and Method. 1500 men were referred for endorectal coil MRI during the period under review; the majority for staging of carcinoma of the prostate. Following a sagittal localizing image, axial T 1 (TR 600/ TE 20 ms), axial T2 (TR 2500/TE 40-80 ms), sagittal T2 and/or coronal T2 weighted images of the prostate were obtained using small (10 14 cm) field of view, thin (3-4 mm) slices and endorectal coil. Results: Numerous prostatic retention cysts and cysts of benign prostatic hypertrophy were identified. 22 cysts of Mullerian duct origin, 2 congenital seminal vesicle cysts, 2 acquired ejaculatory duct cysts and a cystic carcinoma were diagnosed. The relationship of the cyst to the ejaculatory apparatus was sufficiently well demonstrated in each case to make the diagnosis. Conclusion: Endorectal coil MRI is the procedure of choice for the diagnosis of prostatic cystic lesions.

THE SPECTRUM OF NEUROFIBROMATOSIS IN CHILDREN: A PICTORIAL ESSAY M. McPHILLIPS and A. M. O'GORMAN

HIGH RESOLUTION MR IMAGING FOR FUNCTIONAL ENDOSCOPIC SINUS SURGERY G. NEEDHAM, T. REDPATH and K. McLAY

Department of Clinical Radiology and ENT, ARHT, and Department of" Medical Physics, University of Aberdeen, Aberdeen Direct coronal computed tomography (CT) is the imaging technique of choice for chronic sinus disease and is now mandatory prior to F.E.S.S. as high spatial resolution imaging of the osteomeatal unit is necessary. Concerns about the high radiation dose involved in such CT imaging of a relatively young population of sufferers has been expressed. With fast spin echo sequences it is now practical to image the paranasal sinuses by MRI to level of spatial resolution equal to CT (512 matrix). Using T2 weighted sequences perspicuity of mucoperiosteal detail is enhanced and despite the negative signal from cortical bone, useful diagnostic information is achieved. We present our experience with MRI of the paranasal sinuses in 17 patients who were being evaluated prior to F.E.S.S. Fast S.E. TlW and T2W sequences, Fast STIR and Fat Sat T1W and T2W sequences were performed in this group of patients. A subjective scoring of each sequence for anatomic information and pathological information was made. An evaluation of two types of surface coil was also made and the results of these findings will be displayed with suggestions for optimal sequence and coil choice.

Montreal Children's Hospital, Quebec, Canada Neurofibromatosis is a common autosomal dominant condition. NF1 or yon Recklinghausen's disease usually presents in childhood, NF2 or bilateral acoustic neuroma in adolescence or adulthood. We reviewed the radiological findings in a group of 30 children who attended our institution for MR imaging since July 1993. Only 2 (7%) had NF2, the other 28 (93%) had NF1. The commonest radiological finding was that of parenchymal hyperintensities seen on T2W MRI, seen in 75%. Optic glioma was seen in 28%. Plexiform neurofibromata were imaged in 18%. Neurofibromata of nerve roots, often dumbell, were noted in 14%. Soft tissue fibromata were seen in 7%, one showing local bony erosion. 20% had scoliosis, half of whom required surgery. Bony dysplasias were seen in a further 25%. Two had characteristic vascular problems. Several patients had large neurofibromata causing vascular, pharyngeal, optic nerve or cord compression, or severe cosmetic disfigurement. One of two patients with NF2 had many of the recognised findings, with florid disease, unusual in childhood.

CT AND MR APPEARANCES OF SURGICAL PACKING MATERIALS K. I. NG, C. HARTLEY* and A. JACKSON

Departments of Neuroradiology and *Otolaryngology, Central Manchester Health Care Trust, Manchester We have compared CT and MR appearances of Bismuth and Iodoform Paraffin Paste (BIPP), Aqueous Betadine impregnated gauze, Calcium Sodium Alginate (Kaltostat) and Triadcortyl (TAC). Samples of all 4 materials were placed into plastic phials attached to a water phantom and were scanned on a GE 8800 CT scanner. For MR imaging the external auditory canals of two volunteers were packed in turn with each of the packing materials. Volunteers were scanned using a 0.5 T Vectra system. Both T1 (SE 500/21) and T2 (FSE 6000/102) images were obtained. On MR images region of interest measurements were taken from the packing material and from muscle, bone marrow, fat and white matter. On CT images BIPP showed a high attenuation (> 3000 HU) which was associated with marked streak artefact. Aqueous Betadine gauze

ABSTRACTS was also of high attenuation (263 + / - 21 HU) but did not give rise to any decrease in image quality. The attenuation values for Kaltostat (91 + / - 6.1 HU) and TAC (74.9 + / - 49 HU) fell within the attenuation range of soft tissue and fat respectively. On MR images BIPP and Kaltostat showed similar signal characteristics to muscle whilst the signal intensities of aqueous Betadine and TAC were indistinguishable from bone marrow and fat respectively on both T1 and T2 weighted images. Radiologists should be aware of the potential pitfalls of mistaking surgical packing materials for organic material on both CT and M R images.

IMAGING OF DISSECTING NEUROPATHIC JOINTS W. C. G. PEH, J. BROCKWELL, M. T. C H A U and M. M. T. N G

Departments of Diagnostic Radiology, Orthopaedic Surgery and Medicine, The University of Hong Kong and Queen Mary Hospital, Hong Kong Introduction: Unlike the Charcot-like joint seen in the diabetic foot, true neuropathic joints are rarely encountered in modern clinical practice. The imaging features of three cases of dissecting neuropathic joints are described. Subjects and Materials: Three patients, none of whom were previously known to have nenropathic arthropathy, were seen over a six month period. Two patients had chronic renal failure while the third was found to have classical syphilitic neuroarthropathy. They presented with painful swellings o f the thigh, shoulder and forearm respectively, mimicking either thrombophlebitis or soft tissue tumours. All were investigated prospectively. Results: Radiographs and computed tomography (CT) demonstrated destructive changes of the hip, shoulder and elbow joints respectively, with soft tissue bony debris located adjacent to and remote from the joints. All patients had arthrography and post-arthrographic CT which showed tracking of joint contents into the surrounding muscles and fascial planes, with communication to the dissected bony debris. One patient underwent magnetic resonance imaging of the shoulder, confirming CT arthrographic findings. Conclusion: The diagnosis of dissecting neuropathic joint should be considered in patients presenting with painful soft tissue swelling and having radiographic features of neuroarthropathy. CT arthrography is probably the most useful imaging modality for confirmation of this diagnosis.

EMERGENCY TREATMENT OF LIFE-THREATENING H A E M O R R H A G E AFTER RENAL BIOPSY BY SELECTIVE ARTERIAL EMBOLIZATION H. SANSOM and J. MclVOR

Charing Cross Hospital, London The only serious complication of percutaneous renal biopsy is massive haemorrhage, which has an incidence of less than 1%. The treatment of persistent massive haemorrhage by selective renal arterial embolisation is well described, but we have found only one report of this procedure being used in the emergency situation. We report three patients with life threatening haemorrhage post renal biopsy who were successfully treated by selective arterial embolisation on the same day as the biopsy. The three patients had developed severe haemorrhage into the renal tract immediately post biopsy. All required urgent blood transfusion and were being considered for surgery. Selective arterial embolisation, performed within 6 hours of the biopsy controlled the bleeding in all three cases. The catheters and particulate embolisation material used for these cases would be available in most Radiology Departments. Our conclusion is that selective arterial embolisation can be used as an emergency procedure to treat life threatening haemorrhage resulting from percutaneous renal biopsy and that this procedure can be performed by an experienced vascular radiologist without special equipment.

ACQUIRED POSTERIOR URETHRAL DIVERTICULA: A COMPLICATION O F SURGERY FOR HIGH ANORECTAL MALFORMATIONS S. J. VINNICOMBE, C. D. GOOD, C. M. HALL and A. K I N G

Great Ormond Street Hospitalfor Children NHS Trust, London Introduction: Children with high anorectal malformations (ARM's) are prone to urinary problems because of: a) the accompanying

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rectourethral fistula b) associated urinary tract anomalies c) associated neural problems (sacral agensis) d) complications of surgery. The purpose of this study was to highlight the clinical and radiological features of a particular complication of surgery, the posterior urethral diverticulum. Method: We have retrospectively reviewed a series of 5 children with this complication. Results: Recurrent urinary tract infection occurred in all 5; 3 developed enuresis dribbling incontinence; 1 had urinary retention. Ultrasound showed cystic masses behind the bladder in all cases. In 2, this was mistaken for bowel. In another, calculi within the diverticulum were misinterpreted as normal rectal contents. Micturating cystourethrography simultaneously demonstrated the bladder and diverticulum in only 2 cases. In 2, only the diverticulum filled and in 1, only the bladder filled, through the posterior urethra was abnormal. In 1 patient excretory urography was required to identify the bladder. Conclusion: since symptoms are cured by excision of the diverticulum, this diagnosis should be considered in any child with a previous A R M who has a suggestive history. Awareness of the potential pitfalls of imaging will allow prompt diagnosis.

CONGENITAL ANOMALIES OF THE PORTAL VENOUS SYSTEM - C T APPEARANCES WITH EMBRYOLOGICAL CONSIDERATION G. WALSH and M. P. WILLIAMS

Department of Radiology, Derriford Hospital, Plymouth The portal vein is formed by the union of the splenic and superior mesenteric veins behind the neck of the pancreas. This system is derived from the vitelline veins. We present three cases each of which illustrates a congenital variant of the portal venous system, describe their CT appearances and consider the embryological processes accounting for these anomalies. I A 65 year old female with Ca of bronchus was referred for tumour staging. A preduodenal portal view (PPV) was noted. No other anomalies were evident. II A 36 year female with a history of recurrent episodes of acute pancreatitits presented for CT of abdomen. A PPV was noted. In addition SMV rotation, a vertically orientated pancreas and polysplenia were present. I I I A 40 year old male with a family history of Von Hippel-Lindau syndrome presented for screening CT of abdomen. A right sided paraduodenal hernia together with SMV rotation were found Developmental anomalies of the portal venous system are occasional incidental findings in adults. SMV rotation should alert the radiologist to the presence of midgut malrotation and/or internal herniae. A PPV is essential to recognise especially on pre-operative imaging as undetected it represents a significant surgical hazard.

URETERIC PSEUDODIVERTICULA G. WALSH, P. HUGHES, N. RING and M. P. WILLIAMS

Derriford Hospital, Plymouth Ureteric pseudodiverticula (UPD) are outpouchings measuring less than 5 mm in diameter which are occasionally seen as an incidental finding on retrograde/excretory urography. They were first described by Holly and Sumcad in 1957 and since then approximately 100 cases have been reported. U P D have most frequently been found in the elderly male with a history of chronic urinary tract sepsis. Histologically, U P D represent invaginations of hyperplastic transitional epithelium into the lamina propria. The underlying muscularis propria may be effaced but remains intact. Continuity with the ureteric lumen is maintained though U P D may co-exist with both ureteritis cystica and ureteritis glandularis. An increased prevalance of uroepithelial malignancy has been suggested in patients with UPD, one series indicating that the association may be as high as 46%. We wish to illustrate the appearances of this rare condition and present a brief review of its possible aetiology and significance. We describe the findings in two elderly males one of whom had a co-existing transitional cell carcinoma. In conclusion, U P D are an occasional incidental finding on urographic studies. This hyperplastic proliferative change may indicate a degree of uroepithelial instability. This makes recognition of the appearance and possible significance of U P D important as periodic patient review may be indicated.