Diagnostic endoscopy: 2020 vision.
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Diagnostic Imaging↗
Biomedical subjects
Alec J Megibow
Publications and source records attributed to Alec J Megibow.
Evaluation of bowel distention and bowel wall appearance by using neutral oral contrast agent for multi-detector row CT.
PURPOSE: To prospectively evaluate the performance of an orally administered 0.1% barium suspension, Volumen, as a bowel-marking agent for multi-detector row computed tomography (CT). MATERIALS AND METHODS: This HIPAA-compliant study was approved by the Institutional Review Board and conformed to the institutional standards for research funded by a commercial sponsor. A total of 60 patients (33 women, 27 men; average age, 58.2 years) who were referred for multi-detector row CT of the pancreas were randomized into two groups. Prior to examination, group 1 consumed 1200 mL of Volumen over a 30-minute period and group 2 consumed 1200 mL of a solution containing three parts water and one part methylcellulose over a 30-minute period. Results were independently reviewed by two radiologists who were unaware of the contrast agent used. The degree of distention and the visualization of mural detail were qualitatively scored on a five-point scale. Differences were evaluated by using the Mann-Whitney test at a confidence level of 95%. RESULTS: There was significantly better distention in the stomach (P = .013), duodenum (P = .006), jejunum (P = .029), and ileum (P = .014) [corrected] in group 1 compared with group 2. Significant distention was also evident by comparing the products of the widest cross-sectional diameters in duodenum (P = .143), jejunum (P < .001), and ileum (P < .001). Group 1 also demonstrated significantly better visualization of mural features in the duodenum (P = .003), jejunum (P = .024), and ileum (P = .01) and a trend toward better visualization of mural features in the stomach (P = .092). CONCLUSION: Oral administration of Volumen provided excellent distention and excellent visualization of mural features in the gastrointestinal tract.
Administration, Oral↗
Value of the single-phase technique in MDCT assessment of pancreatic tumors.
OBJECTIVE: The purpose of our study was to determine the diagnostic value of single-phase MDCT in patients with suspected pancreatic carcinoma. SUBJECTS AND METHODS: Seventy-one patients (41 men, 30 women; mean age, 63 years; range, 29-80 years) with suspected pancreatic tumor underwent MDCT. Scanning was performed on an MDCT scanner with 0.5-sec gantry rotation and acquisition of 4 slices per rotation. Unenhanced scanning was followed by one set of scanning in the caudocranial direction from the inferior hepatic margin to the diaphragm with a scanning delay of 60 sec after the IV injection of 150 mL of contrast material delivered at 3 mL/sec. Two reviewers independently scored images in a blinded fashion for the presence of tumor and assessment of resectability. Receiver operating characteristic analysis was performed. RESULTS: A final histopathologic diagnosis derived from surgical findings was obtained in 42 patients; in the remaining 29 patients, percutaneous fine-needle aspiration biopsy coupled with a 1-year clinical follow-up to determine development of local, regional or distant neoplasm served as gold standard proof of diagnosis. Final diagnosis was pancreatic cancer in 40 patients (27 ductal adenocarcinoma, nine mucinous cystoadenocarcinoma, two neuroendocrine tumors, one lymphoma, and one papillary cystoadenocarcinoma) and chronic pancreatitis in 31. The mean tumor size was 2.4 cm (range, 4-1 cm). Values for the area under the curve (A(z)) for the assessment of tumor detection were 0.97 for reviewer 1 and 0.96 for reviewer 2 (p = not significant). A(z) values for tumor resectability were 0.90 for reviewer 1 and 0.90 for reviewer 2 (p = not significant). No statistically significant differences were observed between superior mesenteric artery and vein opacification with the hepatic parenchyma enhanced at a time closer to the peak hepatic enhancement, optimizing the detection of hepatic lesions. CONCLUSION: Thin-section single-phase MDCT is an accurate technique for the diagnosis and assessment of resectability in patients with a suspected pancreatic neoplasm. This technique provides optimal tumor-to-pancreas contrast and maximal pancreatic parenchymal and peripancreatic vascular enhancement. It allows visualization of the entire liver and the whole upper abdomen during the portal phase for accurate identification of liver metastases and peritoneal seeding.
Adult↗
Stercoral colitis leading to fatal peritonitis: CT findings.
OBJECTIVE: Stercoral colitis is an inflammatory process involving the colonic wall related to fecal impaction. Our purpose was to describe the imaging findings of stercoral colitis and ulceration and to emphasize the potential serious clinical implications of the condition. CONCLUSION: Fecal impaction may lead to ischemic pressure necrosis and subsequent colonic perforation. In the appropriate clinical setting, the imaging findings that should prompt the radiologist to consider this diagnosis are the presence of fecal impaction, focal colonic wall thickening, and adjacent stranding of the fat. If the fecal impaction is not promptly relieved, the condition can lead to colonic perforation, peritonitis, and patient demise.
Aged↗
Colorectal polyps and cancers in asymptomatic average-risk patients: evaluation with CT colonography.
PURPOSE: To compare thin-section multi-detector row computed tomographic (CT) colonography with conventional colonoscopy in the evaluation of colorectal polyps and cancer in asymptomatic average-risk patients. MATERIALS AND METHODS: Sixty-eight asymptomatic men (age > 50 years) scheduled to undergo screening colonoscopy were enrolled in this study. CT colonography was followed by conventional colonoscopy, performed on the same day. Supine and prone CT colonography were performed after colonic insufflation with room air. A gastroenterologist measured all polyps, which were categorized as 1-5, 6-9, or over 10 mm. Biopsy and histologic evaluation were performed of all polyps. CT colonography and colonoscopy results were compared for location, size, and morphology of detected lesions. Point estimates and 95% CIs were provided for specificity and sensitivity of CT by using results at conventional colonoscopy as the reference standard. RESULTS: At colonoscopy, 98 polyps were identified in 39 patients; 21 (21.4%) of 98 were detected at CT colonography. Sensitivity was 11.5% (nine of 78) for polyps 1-5 mm, 52.9% (nine of 17) for polyps 6-9 mm, and 100% (three of three) for polyps over 10 mm. Results at colonoscopy were normal in 29 (42.6%) of 68 patients; at CT colonography, results were correctly identified as normal in 26 of these 29 patients. In one of these patients, a lesion larger than 10 mm was detected at CT colonography. The per-patient specificity of CT was 89.7% (26 of 29; 95% CI: 72.7%, 97.8%). The mean time for CT image interpretation was 9 minutes. CONCLUSION: In patients at average risk for colorectal cancer, CT colonography is a sensitive and specific screening test for detecting polyps 10 mm or larger; the sensitivity for detecting smaller polyps is decreased. Examination findings can be interpreted in a clinically feasible amount of time.
Animals↗
Frequency and relevance of the "small-bowel feces" sign on CT in patients with small-bowel obstruction.
OBJECTIVE: We sought to determine the incidence of the "small-bowel feces" sign (SBFS) in patients with small-bowel obstruction (SBO) and whether it can be used to accurately locate the point of obstruction. SUBJECTS AND METHODS: From November 2002 until March 2003, 34 consecutive adult patients with CT findings of small-bowel obstruction were prospectively evaluated. The CT findings used to diagnose small-bowel obstruction were a dilated proximal small bowel and a collapsed distal small bowel and colon. CT scans were evaluated to determine the degree of obstruction (mild, moderate, or high-grade), the presence or absence of the SBFS (defined as particulate-type material in the dilated small bowel), the location of the SBFS in relation to the transition zone, and the cause of the obstruction. Mild obstruction was defined as a slight discrepancy between the caliber of the proximal and that of the distal small bowel; moderate SBO was defined as a discrepancy of 50% or more between the calibers of the proximal and the distal small bowel; and high-grade SBO was considered to be present if the distal small bowel and the colon had collapsed. The cause of the obstruction was determined from surgical findings or a combination of CT findings, follow-up barium studies, and clinical assessment. RESULTS: The SBFS was present in 19 (55.9%) of 34 patients with SBO. The degree of SBO was mild in six, moderate in 11, and high-grade in 17 of the patients. The SBFS was present in one of the six patients (16.6%) with mild, eight (72.7%) of the 11 with moderate, and 10 (58.8%) of the 17 with high-grade SBO. In all patients in whom the SBFS was present, the particulate material could be traced to the point of transition and was most conspicuous in the transition zone. The length of fecallike material ranged from 2 to 25 cm and was longer in moderate and high-grade SBO than in mild SBO. The cause of the SBO was an adhesion in 20 patients, a hernia in four patients, Crohn's disease in four patients, a tumor in three patients, and other miscellaneous causes in three patients. CONCLUSION: When present on CT, the SBFS can be used to help locate the transition zone in patients with SBO. The sign is present more frequently in patients with moderate and high degrees of SBO.
Adult↗
CT of GI trauma.
Traumatic bowel and mesenteric injuries are notoriously difficult to diagnose. CT has become the modality of choice for evaluating stable trauma patients for the presence of intra-abdominal injury. This article will summarize the CT findings useful for detecting bowel and mesenteric injury.
Contrast Media↗
Computed tomography diagnosis utilizing compressed image data: an ROC analysis using acute appendicitis as a model.
Using receiver-operating characteristic (ROC) methodology, the ability to diagnose acute appendicitis with computed tomography (CT) images displayed at varying levels of lossy compression was evaluated. Nine sequential images over the ileocecal region were obtained from 53 consecutive patients with right lower quadrant pain who were clinically suspected to have acute appendicitis. Thirty were proven surgically to have acute appendicitis, alternative diagnoses confirmed in 23. The image sets were subjected to a lossy wavelet-based compression algorithm "Embedded Predictive Wavelet Image Coder" (EPWIC). Compression levels were: none, 8:1, 16:1, and 24:1, resulting in 4 sets of images per patient. Image sets were randomized and evaluated separately by 4 body radiologists on a 1,024 x 768-pixel SVGA color PC monitor in 512 x 512 format. The readers were aware of the clinical suspicion of appendicitis but were unaware of the positive fraction of cases. Individual and combined reader ROC and c2 analyses of sensitivity, specificity, and accuracy were determined. For all readers, sensitivity decreases at 16:1 and 24:1 levels (P <0.01, P <0.001, respectively). Accuracy decreased at 24:1 levels (P <0.01). Specificity was unaffected. By ROC analysis there was statistically significantly decreased area under the curve at 24:1 levels (P <0.02) as compared with uncompressed images. Finite levels of lossy wavelet compression may be applied to CT images without compromising diagnostic performance.
Acute Disease↗
Colorectal neoplasms: prospective comparison of thin-section low-dose multi-detector row CT colonography and conventional colonoscopy for detection.
PURPOSE: To prospectively compare thin-section low-dose multi-detector row computed tomographic (CT) colonography with conventional colonoscopy for the detection of colorectal neoplasms. MATERIALS AND METHODS: One hundred five patients underwent CT colonography immediately before colonoscopy. Supine and prone CT colonographic acquisitions to image the region during a 30-second breath hold were performed. CT colonographic images were prospectively interpreted for the presence, location, size, and morphologic features of polyps. The time of image interpretation was noted. Sensitivity, specificity, and positive and negative predictive values of CT colonography were calculated, with 95% CIs, by using colonoscopic findings as the reference standard. The weighted CT dose index was calculated on the basis of measurements in a standard body phantom. Effective dose was calculated by using commercially available software. RESULTS: Median CT data interpretation time was 12 minutes. One hundred thirty-two polyps in 59 patients were identified at colonoscopy; no polyps were detected in 46 patients. Sensitivities for detection of polyps smaller than 5 mm, 6-9 mm, and larger than 10 mm in diameter were 12% (11 of 91 polyps), 70% (19 of 27 polyps), and 93% (13 of 14 polyps), respectively. Estimated overall specificity was 97.7% (515 of 527 imaging results). The total weighted CT dose index for combined supine and prone CT colonography was 11.4 mGy. The effective doses for combined CT colonography were 5.0 mSv and 7.8 mSv for men and women, respectively. CONCLUSION: Low-dose multi-detector row CT colonography has excellent sensitivity and specificity for detection of colorectal neoplasms 10 mm and larger.
Aged↗
Dual-phase versus single-phase helical CT to detect and assess resectability of pancreatic carcinoma.
OBJECTIVE: The aim of this study was to compare dual-phase and single-phase helical CT for the detection and assessment of resectability of pancreatic adenocarcinoma. SUBJECTS AND METHODS: We studied 60 patients (31 men, 29 women; age range, 31-84 years; mean age, 62 years) with suspected pancreatic malignancy. Patients were randomly assigned to one of two groups. For group A (n = 30), unenhanced scans through the liver and pancreas were followed by two separate acquisitions (dual-phase) at 20-25 and at 60-80 sec after IV contrast administration. For group B (n = 30), unenhanced scans were followed by one set of scans (single-phase) acquired caudocranially (from the inferior hepatic margin to the diaphragm) starting 50 sec after IV contrast administration. Two observers independently scored images for the presence of tumor and for assessment of tumor resectability. RESULTS: Comparison of dual-phase versus single-phase helical CT for tumor detection showed a diagnostic accuracy for observer 1 of 87% and 90%, respectively, and for observer 2, of 90% and 87%, respectively. For both helical CT techniques, the overall agreement between the two observers was 83% (kappa = 0.73 +/- 0.03) for single-phase helical CT and 90% (kappa = 0.89 +/- 0.03) for dual-phase helical CT. The assessment of resectability was affected by the low number of resectable tumors (n = 8). CONCLUSION: Single-phase helical CT is effective for the diagnosis and assessment of resectability of patients with suspected pancreatic carcinoma. Advantages are the lower radiation dose and fewer images to film and store.
Adenocarcinoma↗
Cystic pancreatic neoplasms: CT appearances.
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Female↗