Low radiation dose multislice CT colonography in children: Experience after 100 studies

The purpose of this study was to determine the sensitivity (S) and specificity (sp) of virtual colonoscopy in the detection of elevated lesions in children, and to compare these results with conventional colonoscopy. Between April 2000 and January 2003, 100 patients (mean: 6 years old) were evaluated with virtual colonoscopy and conventional colonoscopy. All patients presented rectal bleeding and both methods were performed the same day. All patients had received a standard bowel cleansing the day before. Virtual colonoscopies were carried out with 2.5 mm thick slices, 1.3 mm reconstruction intervals, 15 mAs, and 90 kV. The acquisition time ranged from 5-10 s depending on the age of the patient. For each method, two scans were performed in both a supine and a prone position. After the acquisitions, images were reprocessed using two-dimensional, volume rendering, and virtual endoscopy reconstructions. Findings of the two methods were compared blinded. They were classified in two groups: (1) normal studies, and (2) elevated lesions studies. The second group was subdivided according to the diameter of the lesions: (2a) <5 mm, (2b) 5-9 mm, and (2c) >9 mm. All studies were performed without complications. Forty-eight patients were normal. In the other 52 patients, virtual colonoscopy detected 86 lesions, whereas conventional colonoscopy depicted only 80 lesions. There were 70 true-positive findings, 48 true-negative findings, 12 false-positive findings, and 8 false-negative findings. The global S was 89%, sp: 80%, positive predictive value: 85%, and negative predictive value: 85%. In group (2a), sensitivity, specificity, positive predictive value, and negative predictive value were 81, 90, 81, and 90% respectively; in group (2b), 90, 90, 85, and 94%, respectively; and in group (2c), 100, 96, 90, and 100%, respectively. We concluded that virtual colonoscopy is an alternative method for the evaluation of children with elevated lesions. It is fast, has no complications, and uses a low radiation dose.