CT colonography for incomplete or contraindicated optical colonoscopy in older patients.

OBJECTIVE: Our purpose was to assess the performance of CT colonography (CTC) in patients older than 60 years who were referred because colonoscopy was contraindicated or incomplete. MATERIALS AND METHODS: Over a 2-year period, 61 patients underwent CTC at our institution, 42 of whom (26 women, 16 men) were 60 years old or older (range, 60-87 years; mean age, 71 years). After 24-48 hours of ingesting only clear liquids and after colonic cleansing, fecal tagging, and automated CO2 insufflation, patients were scanned using a 16-MDCT scanner. Images were obtained with the patient in the supine and prone positions and as needed in the right or left decubitus position. Axial 2D and 3D endoluminal views were evaluated on a dedicated workstation. RESULTS: Contraindications to colonoscopy in 12 (29%) of the 42 patients were as follows: anticoagulation (n = 8), increased anesthesia risk (n = 3), and poor tolerance for colonoscopy preparation (n = 1). Incomplete colonoscopy in the other 30 patients (71%) was due to diverticular disease (n = 10), colonic redundancy (n = 10), adhesions (n = 3), residual colonic content (n = 3), sigmoid stricture (n = 1), ventral hernia (n = 1), and unknown cause (n =2). No complications were observed. Optimal distention of the entire colon was achieved in 38 patients (90%). Thirty-nine (93%) of the 42 patients had abnormal findings: diverticular disease (n = 25), one or more polyps (n = 22), a mass lesion (n = 1), a lipoma (n = 1), and inflammatory stricture (n = 1). Extracolonic findings potentially requiring further evaluation or treatment were observed in 26 patients (62%). CONCLUSION: CTC using CO2 insufflation was well tolerated and successful in imaging the entire colon in most of the 42 patients, despite the presence of sigmoid diverticular disease or colonic redundancy.

Independent predictors of acute appendicitis on CT with pathologic correlation.

RATIONALE AND OBJECTIVES: To assess computed tomographic (CT) signs that have been described in published studies for the diagnosis of appendicitis to identify independent findings that predict appendicitis. METHODS AND MATERIALS: A retrospective database search identified 67 patients with a CT scan of the abdomen/pelvis and pathologic evaluation of the appendix, including 41 with appendicitis and 26 with a normal appendix on pathologic examination. Each computed tomogram was re-evaluated by three independent, blinded observers who evaluated appendix diameter, enhancement of the appendix, thickening of the appendix, presence of an appendicolith, infiltration of peri-appendiceal fat, focal cecal thickening, local lymphadenopathy, fluid collections, non-appendiceal bowel thickening, non-periappendiceal infiltration of fat, and comparison of peri-appendiceal fat infiltration to thickening of adjacent bowel loops. RESULTS: Mean diameter of the normal appendix (6.7 +/- 2.2 mm) was significantly lower than that of the inflamed appendix (12.1 +/- 4.3 mm; P < .001). Significant univariate predictors of appendicitis included appendix diameter >8 mm (odds ratio [OR] 34.8), enhancement of the appendix (OR 4.4), thickening of the appendix (OR 4.3), infiltration of peri-appendiceal fat (OR 5.5), focal cecal thickening (OR 5.1), non-appendiceal bowel thickening (OR 0.4), and non-periappendiceal infiltration of fat (OR = 0.3). Of these variables, only appendix diameter and enhancement of the appendix were significant independent predictors of appendicitis on multivariate analysis. An overall diagnostic impression based on all secondary signs was less accurate than a diagnosis based on appendix diameter alone (receiver-operating characteristic analysis: Az = 0.80 vs. Az = 0.91, P = .02). Sensitivity/specificity of appendix diameter was 84%/87% using a cutoff between 8 and 9 mm and 97%/48% using a cutoff between 6 and 7 mm. CONCLUSION: Appendix diameter is the best single diagnostic criterion for appendicitis on CT scan. A cutoff between 8 and 9 mm provided the best balance of sensitivity/specificity in our study population, whereas a cutoff between 6 and 7 mm improved sensitivity at the expense of specificity. The presence of appendiceal enhancement provided additional diagnostic information, but other secondary signs of appendicitis did not improve diagnostic accuracy.