Core biopsy with curved needle technique.

OBJECTIVE: The purpose of this study was to define the technique and study the feasibility of curved needle biopsy performed with a coaxial core biopsy system. CONCLUSION: Curved core needle biopsy is a simple and feasible technique with a high technical success rate even with suboptimal coaxial needle placement. With the technique, different parts of a focal lesion can be biopsied without manipulation of the coaxial needle. This feature may help in avoiding injury to vital structures.

Double-contrast barium enema: use in practice and implications for CT colonography.

OBJECTIVE: This study examines the use and yield of double-contrast barium enemas (DCBEs) for colorectal polyp detection in current clinical practice outside the research setting. MATERIALS AND METHODS: My colleagues and I retrospectively reviewed adult DCBE studies performed in routine clinical practice at a single academic institution from 2001 through 2004 by reviewing the official radiology and colonoscopy reports. Data were collected on indications for a DCBE, number of positive and negative DCBE reports, results of a DCBE after failed colonoscopy, and professional profiles of the radiologists who performed the DCBEs. Correlation for colon polyp detection was made by reviewing reports of colonoscopy performed within 12 months before or after a DCBE. Polyp detection and matching analysis used a six-segment colon localization scheme. RESULTS: A total of 244 out of 665 (36.7%) barium enema studies were performed using the double-contrast technique over the 4-year period-that is, approximately one per week. The most common indication for a DCBE (109/244 or 44.6%) was to complete a failed, incomplete, or inconclusive colonoscopy. Overall, only 14 of the 244 (5.7%) studies gave positive reports for polyps, and of these, five were shown to be false-positive at later colonoscopy. Only six polyps 10 mm or larger were positively detected during the entire study, which is approximately one per 60 studies or one every 8 months. In 104 patients who had negative DCBEs after failed or inconclusive colonoscopy, more than 50 subcentimeter polyps had been detected and removed, yet not one additional polyp was detected by a DCBE. Of the 15 radiologists performing the DCBEs during the study period, 89.7% of the studies were done by four individuals. Three of these four radiologists were older than 60 years at the beginning of the study, and two of them are now either retired or no longer perform fluoroscopy. CONCLUSION: In our center, a DCBE is a low-yield procedure for detecting polyps, with a high false-positive rate, and is not likely to be performed by experienced practitioners in the future.

Automated volumetry at CT colonography: a phantom study.

RATIONALE AND OBJECTIVES: To assess the performance of a computer-aided detection (CAD) algorithm for measuring polyp-like structures on CT colonography (CTC) images of a phantom. MATERIALS AND METHODS: We constructed a Plexiglas phantom to which we affixed a series of idealized Plexiglas polyp-like objects, including spheres and hemispheres. We imaged the phantom in a four-channel detector CT scanner at a 1.3 mm slice thickness with a reconstruction interval of 0.6 mm, using combinations of 100 mAs, 30 mAs, horizontal and vertical orientation. For each set of CT images, the interior surface of the phantom was segmented. The CAD algorithm was applied to the resulting surface to identify the polypoid regions of interest and to calculate their volume and maximum linear dimension. Calculated values were then compared with actual values to yield percent error in each measurement. RESULTS: The mean error in volume for the subgroups of spheres and hemispheres was 3% and 5% respectively. Mean error in linear dimension was approximately 2% for both shape subgroups. All CAD-calculated values were closely correlated with their respective actual values. Parameter selection did not significantly affect the accuracy of the calculated measurements. CONCLUSIONS: Our CAD software accurately measured the greatest linear dimension and the volume of each of the polyp-like structures in our phantom. Results were largely independent of phantom orientation and the CT exposure factors.

Consensus on current clinical practice of virtual colonoscopy.

OBJECTIVE: The purpose of our study was to determine the current opinions regarding the performance, interpretation, reporting, and clinical role of virtual colonoscopy among a group of selected experts to develop a consensus statement. MATERIALS AND METHODS: A questionnaire was sent to 33 selected experts in virtual colonoscopy. Responses were tabulated and results were used to develop a consensus statement. The results of the questionnaire and consensus statement were sent to respondents for comment and approval. RESULTS: Thirty-one (93.9%) of 33 surveys were returned. Eighty-seven percent (27/31) of respondents believe virtual colonoscopy is a credible screening method. Oral sodium phosphate solution is the laxative preferred by more than 66% (18/27), whereas 62% (13/21) do not believe fecal tagging is necessary. All respondents (25/25) think that both prone and supine imaging is required, with most (81%, 21/26) believing IV contrast material is not necessary. The routine use of spasmolytics is suggested by only 15% (4/26). The largest acceptable slice thickness of 3 mm is agreed on by 88% (22/25). All respondents believe screening virtual colonoscopy should be performed at a lower dose per slice than conventional CT. Most (80%, 20/25) believe the optimum method of interpreting virtual colonoscopy should be primary axial review, with 3D used for problem solving. All but one respondent (96%, 26/27) agree there is a threshold size below which polyps are not clinically important. When reporting virtual colonoscopy results, 59% (16/27) believe polyps less than 4 mm need not be reported. CONCLUSION: A consensus is developing among experts as to the appropriate manner in which virtual colonoscopy should be performed, interpreted, and reported.

Interventional approach to pancreatic fluid collections.

Interventional radiologic catheter drainage may be an effective therapeutic approach to fluid collections complicating acute pancreatitis. Pancreatic pseudocysts and abscess are the most common conditions requiring radiologic intervention. Imaging guidance is best performed under CT control allowing precise definition of access route, catheter placement, and response. Access routes are chosen to avoid traversing vital intervening structures, especially the pleural space, colon, and small bowel. Optimal results are achieved with the use of large-bore multihole catheters, prolonged duration of drainage, and careful collaboration with the surgical team.