CT Colonography: an update on current and future indications

Is there need for routine CT colonography after CT-verified uncomplicated diverticulitis of the sigmoid colon?

Background

Following an episode of acute diverticulitis, surgical guidelines commonly advise routine colonic follow-up to rule out underlying malignancy. However, as a CT of the abdomen is frequently performed during clinical work-up, the routine need for colonic follow-up has become debated.

Purpose

To evaluate the need for routine CT colonography after an episode of CT-verified uncomplicated sigmoid diverticulitis to rule out underlying colorectal malignancy.

Material and methods

This study retrospectively evaluated 312 patients routinely referred to colonic evaluation by CT colonography following an episode of acute diverticulitis. Patients were excluded if lacking diagnostic CT of the abdomen at time of diagnosis, if presenting with atypical colonic involvement, or if CT findings were suggestive of complicated disease (e.g., abscess or perforation). CT colonography exams were routinely reviewed by experienced abdominal radiology consultants on the day of the procedure. If significant polyps were detected, or if colorectal malignancy could not be excluded, patients were referred to same-day optical colonoscopy. For these patients, medical records were reviewed for optical colonoscopy results and histology reports if applicable.

Results

Among 223 patients with CT-verified uncomplicated sigmoid diverticulitis, no patients were found to have underlying colorectal malignancy. 27 patients were referred to optical colonoscopy based on CT colonography findings. 18 patients consequently underwent polypectomy, all with either hyperplastic or adenomatous histology.

Conclusions

This study indicates that routine colonic evaluation by CT colonography following an episode of CT-verified uncomplicated sigmoid diverticulitis may be unwarranted, and should arguably be reserved for patients with protracted or atypical clinical course.

Advanced diagnostic endoscopy in the lower gastrointestinal tract: A review of JGES core sessions

At each of the 89th to the 92nd congresses of the Japan Gastroenterological Endoscopy Society, a series of featured discussion sessions concerning advanced diagnostic endoscopy in the lower gastrointestinal tract were presented. In total, 45 lectures were presented in this subject area. It was shown that, in recent years, several convenient and less invasive colonoscopic modalities have been developed. This review article summarizes these core sessions and the efficacy of the techniques discussed.

Increasing Navigation Speed at Endoluminal CT Colonography Reduces Colonic Visualization and Polyp Identification

As navigation speed increases, gaze of the reader becomes more central and polyp identification rates fall.

Purpose

To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography

Materials and Methods

Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling.

Results

Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively).

Conclusion

Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification.

^© RSNA, 2017

Online supplemental material is available for this article.