Biomedical subjects

John M Barlow

Publications and source records attributed to John M Barlow.

4 recordsLinked to original sources

PubMed2006

Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.

PURPOSE: To retrospectively evaluate small-bowel enhancement characteristics and the sensitivity, specificity, and interobserver agreement of computed tomographic (CT) findings by using histologic and endoscopic results as a reference standard in patients undergoing enteric phase CT enterography. MATERIALS AND METHODS: The institutional review board approved this retrospective HIPAA-compliant study, which included patients who consented to having their medical records used for research purposes. Enteric phase CT enterographic and ileoscopic findings with or without ileal histologic results were examined in 42 patients (24 women, 18 men). Enteric phase CT enterography was performed after 150 mL of intravenous contrast material was administered at 4 mL/sec, with a 45-second delay. Mural attenuation was measured in the distended and collapsed jejunal and ileal loops and in the terminal ileum. Two radiologists examined CT images for findings of Crohn disease. Mural attenuation for different bowel loops was compared by using a Student t test, with kappa statistics used to measure interobserver agreement and Pearson correleation coefficients used to compare visual and quantitative measures. RESULTS: Distended jejunal loops had significantly greater attenuation than distended ileal loops (113 HU vs 72 HU; P < .001). Attenuation of collapsed jejunal (134 HU) and ileal (108 HU) loops was greater than that of distended jejunal and ileal loops (P < .001). Terminal ileal enhancement was the most sensitive visual CT finding of Crohn disease for both radiologists. Mural thickening demonstrated the greatest interobserver agreement (kappa = 0.83). Visual enhancement and quantitative mural attenuation were significantly correlated (P < .003). CONCLUSION: At enteric phase CT enterography, jejunal attenuation is greater than ileal attenuation and collapsed bowel loops demonstrate greater attenuation than distended bowel loops. Mural hyperenhancement and increased mural thickness are the most sensitive CT findings of active Crohn disease.

Adult↗

PubMed2006

Crohn Disease: mural attenuation and thickness at contrast-enhanced CT Enterography--correlation with endoscopic and histologic findings of inflammation.

PURPOSE: To determine retrospectively if quantitative measures of small-bowel mural attenuation and thickness at computed tomographic (CT) enterography correlate with endoscopic and histologic findings of small-bowel inflammation and to estimate the performance of these measures in predicting inflammatory Crohn disease. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant retrospective study, which was conducted with patient informed consent. CT enterography data in 96 patients (31 male patients and 65 female patients) who underwent ileoscopy with or without biopsy were examined for CT signs of active Crohn disease. The most highly enhancing segment of terminal ileum and a normal-appearing ileal loop were identified. After it was confirmed that semiautomated software could accurately measure mural attenuation and thickness, the selected terminal ileal and normal-appearing (control) ileal loops were examined (20 automated measurements at each location) to quantify mural attenuation and wall thickness. Results were compared with endoscopy and histology reports by using logistic regression analysis and receiver operating characteristic curves. RESULTS: Quantitative measures of terminal ileal mural attenuation and wall thickness correlated significantly with active Crohn disease (P < .001). Small-bowel wall thickness was not a significant factor after attenuation was taken into account. A threshold attenuation value with a sensitivity of 90% (18 of 20) for definite Crohn disease (compared with a sensitivity of 80% [16 of 20] for radiologist assessment) was selected. In patients who underwent ileal biopsy, threshold attenuation had a sensitivity identical to that of ileoscopy (81% [26 of 32]; 95% confidence interval: 64%, 93%) in predicting histologic inflammation. CONCLUSION: Quantitative measures of mural attenuation and wall thickness at CT enterography correlate highly with ileoscopic and histologic findings of inflammatory Crohn disease. Quantitative measures of mural attenuation are sensitive markers of small bowel inflammation.

Adolescent↗

PubMed2004

Understanding interpretive errors in radiologists learning computed tomography colonography.

RATIONALE AND OBJECTIVES: To determine if interpretive errors in the course of learning CT colonography are secondary to failures in detection or in characterization and determine the types of lesions frequently missed. MATERIALS AND METHODS: Fifteen radiologists completed an electronic CTC training module consisting of two parts: 1) a teaching file demonstrating the varied appearances of polyps, cancers, and pitfalls in interpreting exams; and 2) a test of 50 complete CTC datasets. Following review of each test case, radiologists were asked to indicate if and where a polyp was visualized. The module then showed each neoplasm (if any) located within the dataset. For false negative examinations, radiologists indicated if the lesion was not seen, was seen but interpreted as colonic wall or fold, or was seen but interpreted as stool or fluid. RESULTS: The average sensitivity for sessile, pedunculated, and flat polyps for these novice readers was 76%, 63%, and 32%, respectively. Average sensitivity for all morphologies of cancers (annular, polypoid, flat) was high (93%, 85%, 95%), with 8/11 missed cancers being secondary to failure in detection. The most frequently missed cancer was an annular constricting tumor (5/11). Overall, 55% (73/132) of errors were failures of detection and 45% (59/132) were errors in characterization. CONCLUSION: Radiologists learning CT colonography had slightly more errors of detection than characterization, but this difference was not statistically significant. Flat and pedunculated polyps and annular constricting cancers were the most frequently missed morphologies. Examples of these abnormalities should be emphasized in CTC training programs.

Colonic Neoplasms↗

PubMedDate not supplied

CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases.

Computed tomographic (CT) enterography combines the improved spatial and temporal resolution of multi-detector row CT with large volumes of ingested neutral enteric contrast material to permit visualization of the small bowel wall and lumen. Adequate luminal distention can usually be achieved with oral hyperhydration, thereby obviating nasoenteric intubation and making CT enterography a useful, well-tolerated study for the evaluation of diseases affecting the mucosa and bowel wall. Unlike routine CT, which has been used to detect the extraenteric complications of Crohn disease such as fistula and abscess, CT enterography clearly depicts the small bowel inflammation associated with Crohn disease by displaying mural hyperenhancement, stratification, and thickening; engorged vasa recta; and perienteric inflammatory changes. As a result, CT enterography is becoming the first-line modality for the evaluation of suspected inflammatory bowel disease. CT enterography has also become an important alternative to traditional fluoroscopy in the assessment of other small bowel disorders such as celiac sprue and small bowel neoplasms.

Contrast Media↗