Gas-containing gallstones as a cause of the "effervescent gallbladder" sign and pneumobilia.

The "effervescent gallbladder" sign, the sonographic finding of tiny echogenic foci rising from the dependent portion of the gallbladder, reminiscent of bubbles rising in a glass of champagne, has been reported previously as a finding of emphysematous cholecystitis. We report two additional cases of this unusual finding in an asymptomatic patient and in a patient with acute, gangrenous cholecystitis, confirmed in both cases by CT, to be secondary to the release of gas from gallstones. These two cases cast doubt on the sonographic sign as a pathognomonic finding of emphysematous cholecystitis.

Feasibility of using a walking workstation during CT image interpretation.

OBJECTIVE: Two-thirds of the US population is overweight or obese. Sedentary lifestyles and occupations are one factor in the development of obesity. Methods to help reduce sedentary work environments may help reduce obesity. The purpose of this study was to determine the feasibility of using a walking workstation during computed tomographic image interpretation. METHODS: Two radiologists reinterpreted 100 clinical computed tomographic examinations they had previously interpreted, each while walking at 1 mph on a treadmill using an electronic workstation. Ten cases were reviewed per session. The time period between the initial conventional interpretations and the reinterpretations was greater than one year, to reduce recall bias. Discrepant findings were ranked according to a classification system based on clinical importance on a scale ranging from 1 to 6. Discrepant findings classified as greater than or equal to 3 were considered significant. Detection rates for the initial interpretations and reinterpretations were determined for each reviewer and compared using a paired t-test. RESULTS: A total of 1,582 findings were reported (825 by reviewer 1 and 757 by reviewer 2). There were 459 findings with clinical importance of 3 or higher. For reviewer 1 (91 cases of at least one important finding), the mean detection rates were 99.0% for the walking technique and 88.9% for the conventional interpretations (P = .0003). For reviewer 2 (89 cases with at least one important finding) the mean detection rates were 99.1% for the walking technique and 81.3% for the conventional interpretations (P < .0001). CONCLUSION: The use of a walking workstation for the interpretation of cross-sectional images is feasible. Further studies are needed to assess the potential impact on diagnostic accuracy.

Noncathartic CT colonography with stool tagging: performance with and without electronic stool subtraction.

OBJECTIVE: The purpose of our study was to evaluate the performance of noncathartic, dietary unrestricted CT colonography, without and with the aid of electronic stool subtraction, for detecting colorectal neoplasia in a high-prevalence referral population. MATERIALS AND METHODS: Patients with known or suspected colorectal neoplasms were potentially eligible for participation, regardless of the presence or absence of gastrointestinal symptoms. Subjects ingested 21.6 g of barium in nine divided doses. CT colonography was performed in the standard fashion. Data sets were randomly evaluated by two of three experienced radiologists, with subsequent reanalysis of each data set after electronic stool subtraction at least 6 weeks later. Optical colonoscopy was performed after purgation and served as the reference standard. RESULTS: One hundred thirty-one adenomatous neoplasms were identified among 114 subjects. On a per subject basis, the sensitivity for detecting adenomas 6-9 or > or = 10 mm in diameter ranged from 53% to 88% and 84% to 93% without stool subtraction, respectively. By including stool subtraction, these sensitivity estimates improved to 68% to 92% and 93% to 94%, respectively. Specificity ranged from 71% to 91% and 88% to 100% for lesions 6-9 and > or = 10 mm in size, respectively. Double reading resulted in detection of 27 (87%) of 31 and 65 (96%) of 68 patients with 6-9 and > or = 10 mm adenomas, respectively. With double reading, the area under the receiver operating characteristic curve for large adenomas was 0.97. CONCLUSION: In this increased-risk referral population, CT colonography in the non-cathartic-tagged colon without dietary restrictions compared favorably with optical colonoscopy.

Effect of slice thickness and primary 2D versus 3D virtual dissection on colorectal lesion detection at CT colonography in 452 asymptomatic adults.

OBJECTIVE: The objective of our study was to compare the performance of primary 3D search using 360 degree virtual dissection with primary 2D search using a 2.5- versus a 1.25-mm slice thickness. SUBJECTS AND METHODS: Four hundred fifty-two asymptomatic patients underwent CT colonography (CTC) and colonoscopy. Examinations were reconstructed to 1.25- and 2.5-mm slice thicknesses and interpreted using primary 3D search (360 degree virtual dissection) and primary 2D search. Two of three experienced reviewers were randomly assigned to each case; 1,808 interpretations were performed. RESULTS: There were 64 adenomas > or = 6 mm, 26 of which were large adenomas > or = 1 cm. For adenomas 6-9 mm in diameter, the area under the receiver operating characteristic curve (AUC) using 2.5-mm data sets was 0.66, 0.62, 0.90 and 0.78, 0.69, 0.67 for reviewers 1, 2, and 3, respectively, using primary 3D versus 2D search (p = not significant [NS]). For neoplasms > or = 10 mm, the AUC using 2.5-mm data sets was 0.74, 0.85, 0.89 and 0.66, 0.86, 0.92 for reviewers 1, 2, and 3 using primary 3D versus 2D search (p = NS). There was no significant difference using 1.25-mm collimation. Double review using both primary 3D and 2D search yielded sensitivities of 84% (16/19) and 95% (18/19) for large neoplasms (> or = 1 cm) using 2.5- and 1.25-mm data sets, respectively. Five of five (100%) adenocarcinomas were identified. The sensitivity of colonoscopy for large neoplasms was 77% (20/26) (20% [1/5] for adenocarcinoma). CONCLUSION: No advantage exists for 1.25- or 2.5-mm slice thickness or for primary 3D versus 2D search at CTC. Double review using primary 3D (virtual dissection) and 2D search reduces interobserver variability and competes with colonoscopy for the detection of large lesions.

Occult colorectal polyps on CT colonography: implications for surveillance.

OBJECTIVE: Our purpose was to determine the prevalence of polyps that are invisible on CT colonography (CTC) in a population previously screened for colorectal neoplasms. Differences in the prevalence of occult polyps in various populations might help explain the discordant reported sensitivities for polyp detection in published reports of CTC. SUBJECTS AND METHODS: Seventy-five consecutive patients who had been previously screened for polyps underwent same-day colonoscopy and CTC. Many of the patients had personal histories of previous polypectomies and were undergoing surveillance colonoscopy. The scans were interpreted prospectively by an experienced radiologist. Polyps missed prospectively on CTC were analyzed retrospectively by three experienced radiologists and categorized as perception errors (visible in retrospect), technical errors (e.g., obscured by feces or fluid), or occult (invisible). RESULTS: Thirty polyps 5 mm or larger were found at colonoscopy, 18 of which were missed prospectively on CTC. Of the 18 missed polyps, 12 could not be identified in retrospect, even though they were located in clean, dry, well-distended colonic segments. These were classified as occult. Ten of the 12 occult polyps showed flat morphology on review of colonoscopy video recordings. Of the remaining six missed polyps, two were classified as perception errors, two as technical errors, and two as a combination of technical and perception error. CONCLUSION: In this population, colonographically occult polyps were common and accounted for more detection failures than perception errors and technical errors combined. The high prevalence of occult polyps may be explained by the fact that previous screening may have led to removal of easy-to-see polyps, creating a study population with a higher percentage of hard-to-see polyps.

CT colonography using 360-degree virtual dissection: a feasibility study.

OBJECTIVE: Using a 3D rendering technique called "virtual dissection," we sought to evaluate polyp and fold distortion using a colon phantom, estimate the polyp detection performance in humans, and estimate the added benefit of double interpretation and computer-aided diagnosis. MATERIALS AND METHODS: A colon phantom containing 144 polyps of varying sizes (5-12 mm) and shapes (flat, sessile, pedunculated) was scanned. Polyp shape and distortion at virtual dissection were categorized as flame, club, pea, or bizarre. Haustral fold distortion was graded. The CT colonography examinations in 20 consecutive patients (colonoscopically proven normal findings, n = 5; polyps > or = 1 cm, n = 17 in 15 patients) were blindly reviewed by three radiologists using the virtual dissection technique. The added benefits of double interpretation and computer-aided diagnosis were tabulated. RESULTS: Sessile polyps appeared flame (35/48 [73%]) or pea (11/48 [23%]) in shape. Flat polyps appeared flame-shaped (31/47 [66%]) or pea-shaped (16/47 [34%]). Pedunculated polyps were flame (15/45 [33%]), club (20/45 [44%]), or pea (6/45 [13%]) in shape. Axial distortion occurred along the longitudinal axis. The sensitivities of the three observers for polyps of 1 cm or more were 16/17 (94%), 14/17 (82%), and 15/17 (88%). The specificities were 5/5 (100%), 5/5 (100%), and 4/5 (80%). Sensitivities after double interpretation and computer-aided diagnosis improved but did not reach statistical significance. CONCLUSION: Although distortion of colonic structures exists at virtual dissection, it does so in recognizable patterns, so that sensitivity for polyp detection is not compromised.

Comparison of the relative sensitivity of CT colonography and double-contrast barium enema for screen detection of colorectal polyps.

BACKGROUND & AIMS: In a population reflective of a screening setting, our aim was to compare the relative sensitivity and specificity of computed tomography (CT) colonography with double-contrast barium enema (DCBE) for detection of colorectal polyps and to assess the added value of double reading at CT colonography, using endoscopy as the arbiter. METHODS: This prospective, blinded study comprised 837 asymptomatic persons at higher than average risk for colorectal cancer who underwent CT colonography followed by same-day DCBE. Examinations with polyps > or =5 mm in diameter were referred to colonoscopy. RESULTS: CT colonography readers detected 56%-79% of polyps > or =10 mm in diameter. In comparison, the sensitivity at DCBE varied between 39% and 56% for the 31 polyps > or =1 cm. All of the readers detected more polyps at CT colonography than DCBE, but the difference was statistically significant for only a single reader (P = 0.02). Relative specificity for polyps > or =10 mm on a per-patient basis ranged from 96% to 99% at CT colonography, and 99%-100% at DCBE. Doubly read CT colonography detected significantly more polyps than DCBE (81% vs. 45% for polyps > or =1 cm [P = <0.01], and 72% vs. 44% for polyps 5-9 mm [P < or = 0.01]). CONCLUSIONS: Double-read CT colonography is significantly more sensitive in detecting polyps than single-read double contrast barium enema. DCBE was significantly more specific than CT colonography.

Characterization of lesions missed on interpretation of CT colonography using a 2D search method.

OBJECTIVE: We examined potential factors that may cause false-negative results on CT colonography examinations. MATERIALS AND METHODS: In this prospective and retrospective study, 500 asymptomatic patients at high risk for colorectal cancer underwent CT colonography and colonoscopy. Each CT data set was interpreted by two independent observers, who were unaware of endoscopic findings, using a method of searching through enlarged axial images to detect intraluminal lesions. Another observer identified and characterized lesions missed at prospective interpretation. Polyps were assessed for size, method of visualization, intrinsic and extrinsic features, and examination quality. RESULTS: We found 116 polyps at least 5 mm in diameter, 54 (47%) of which were missed by at least one of the prospective observers. Polyps seen in only one position were missed more often than polyps seen in both supine and prone positions (84% vs 50%, p < 0.01). Polyps located in suboptimally prepared colonic segments or along a thickened colonic wall were more frequently missed (p = 0.02 and p = 0.05, respectively). Endoscopic morphology and irregular surface contour were associated with missed lesions of all sizes (p = 0.03 and p = 0.04, respectively). Rounded intraluminal lesions were detected more often than other morphologies on CT (p = 0.04). CONCLUSION: Factors that influence the likelihood that a polyp may be missed at interpretation of CT colonography include being seen only in one position, having flat endoscopic or CT morphology, having surface irregularity, and being located in a poorly prepared segment or along a thickened colonic wall. Understanding these features should lead to improved polyp detection on CT colonography.

Computerized tomographic colonography: performance evaluation in a retrospective multicenter setting.

BACKGROUND & AIMS: No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps >or=10 mm in diameter) in a multi-institutional study. METHODS: A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps >or=10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms. RESULTS: The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion >or=10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms. CONCLUSIONS: Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps.

BACKGROUND & AIMS: This study used a low lesion prevalence population reflective of the screening setting to estimate the sensitivity and specificity of computerized tomographic (CT) colonography for detection of colorectal polyps. METHODS: This prospective, blinded study comprised 703 asymptomatic persons at higher-than-average risk for colorectal cancer who underwent CT colonography followed by same-day colonoscopy. Two of 3 experienced readers interpreted each CT colonography examination. RESULTS: Overall lesion prevalence for adenomas >/=1 cm in diameter was 5%. Seventy percent of all lesions were proximal to the descending colon. With colonoscopy serving as the gold standard, CT colonography detected 34%, 32%, 73%, and 63% of the 59 polyps >/=1 cm for readers 1, 2, 3, and double-reading, respectively; and 35%, 29%, 57%, and 54% of the 94 polyps 5-9 mm for readers 1, 2, 3, and double-reading, respectively. Specificity for CT colonography ranged from 95% to 98% and 86% to 95% for >1 cm and 5-9-mm polyps, respectively. Interobserver variability was high for CT colonography with kappa statistic values ranging from -0.67 to 0.89. CONCLUSIONS: In a low prevalence setting, polyp detection rates at CT colonography are well below those at colonoscopy. These rates are less than previous reports based largely on high lesion prevalence cohorts. High interobserver variability warrants further investigation but may be due to the low prevalence of polyps in this cohort and the high impact on total sensitivity of each missed polyp. Specificity, based on large numbers, is high and exhibits excellent agreement among observers.

Extracolonic findings at CT colonography: evaluation of prevalence and cost in a screening population.

BACKGROUND & AIMS: To assess the prevalence and spectrum of extracolonic findings in a screening population undergoing computed tomography colonography (CTC), and to evaluate the short-term direct medical costs incurred from subsequent radiologic follow-up evaluation. METHODS: Six hundred and eighty-one asymptomatic patients undergoing colonoscopy screening consented to a CTC examination. Extracolonic CT findings were classified into high, medium, and low importance. Clinical and radiologic follow-up, missed lesions, and outcomes were assessed by chart review (time interval, 410-1513 days; median, 913 days). Short-term direct medical costs of radiologic follow-up were determined based on Medicare 2002 reimbursement rates. RESULTS: Extracolonic findings were found commonly. These were categorized as high clinical importance in 71 (10%) individuals, as medium importance in 183 individuals (27%), and as low importance in 341 individuals (50%). Subsequent medical or surgical interventions resulted from these findings in 9 of the 681 patients (1.3%). Costs of subsequent radiologic follow-up studies were calculated as $23,380.59 (average added costs per CTC examination $34.33). CONCLUSIONS: CTC commonly detects extracolonic findings that can be considered clinically important when applied to an asymptomatic screening population. Although such incidental findings add benefit to the screening intervention, moderate incremental costs are incurred based on additional radiologic procedures generated during short-term follow-up.

A prospective, blinded assessment of the impact of preoperative staging on the management of rectal cancer.

BACKGROUND & AIMS: The influence of preoperative staging of rectal carcinoma on therapeutic decisions is uncertain. The use of fine-needle aspiration (FNA) of perirectal nodes in this setting has not been evaluated. The aim of this prospective, blinded study of patients with rectal cancer was to assess the impact of preoperative staging on treatment decisions and compare the tumor (T), nodal (N) staging performance characteristics of pelvic computed tomography (CT), rectal endoscopic ultrasonography (EUS), and EUS FNA. METHODS: Eighty consecutive patients with newly diagnosed rectal cancer were prospectively evaluated. Therapy decisions were recorded after sequential disclosure of staging information to the patient's surgeon. RESULTS: In 31% of patients (95% confidence interval, 21%-42%), EUS staging information changed the surgeon's original treatment plan based on CT alone. The further addition of FNA changed therapy in one patient. T staging accuracy was 71% (CT) and 91% (EUS) (P = 0.02); N staging accuracy was 76% (CT), 82% (EUS), and 76% (EUS FNA) (P = NS). CONCLUSIONS: Preoperative staging with EUS results in more frequent use of preoperative neoadjuvant therapy than if staging was performed with CT alone. The addition of FNA only changed the management of one patient, whereas FNA did not significantly improve N staging accuracy over EUS alone. FNA seems to offer the most potential for impacting management in those patients with early T stage disease, and its use should be confined to this subgroup of patients. EUS is more accurate than CT for determining T stage of rectal carcinoma.

Pirfenidone in the treatment of primary sclerosing cholangitis.

Our aim was to evaluate the safety and assess the efficacy of pirfenidone, an antifibrotic drug, in patients with primary sclerosing cholangitis (PSC). Twenty-four patients with PSC were enrolled in this pilot study. Oral pirfenidone, 2400 mg daily, was given for one year. Liver biochemistries were determined at three-month intervals. The Mayo risk score was calculated, and liver biopsy and endoscopic cholangiography were performed at entry and at one year of treatment. No significant changes in liver biochemistries were noted at the end of the treatment period or at any of the three-month intervals. The Mayo risk score did not change significantly, and no significant changes were noted in the degree of inflammation, fibrosis, histologic stage of disease, or cholangiographic findings at the end of the treatment period. Adverse events occurred in 20/24 (83%) patients, but disappeared shortly after pirfenidone was discontinued. Pirfenidone did not benefit patients with PSC, and it was frequently associated with adverse events. The results of this pilot study discourage further trials of pirfenidone in patients with PSC.