Ayso de Vries MD, Presenter: Research grant, Koninklijke Philips Electronics NV, Best, Netherlands

Marjolein Liedenbaum MD, Abstract Co-Author: Nothing to Disclose

Jasper Florie MD, Abstract Co-Author: Nothing to Disclose

Yung Nio MD, Abstract Co-Author: Nothing to Disclose

Roel Truyen, Abstract Co-Author: Nothing to Disclose

Jaap Stoker MD, PhD, Abstract Co-Author: Nothing to Disclose

To prospectively evaluate the additional value of CAD when used in a second reader paradigm in CT colonography (CTC) of individuals at increased risk for colorectal cancer (CRC).

138 consecutive patients at increased risk for CRC underwent CTC 3 hours prior to colonoscopy. All patients underwent extensive bowel preparation and fecal tagging (4 * 50ml oral Iodine contrast). After CTC evaluation by an experienced reader (>100 CTC), the candidate lesions detected by CAD were unblinded to the reader. All reader findings and approved CAD findings ≥6mm were evaluated at colonoscopy by segmental unblinding. Per-polyp sensitivity of the observer for large (≥10mm) and medium sized (6-9mm) adenomatous polyps was determined as well as the effect of CAD. The results were stratified for morphology. The per-patient sensitivity and specificity was determined for both size categories.

In 41 patients 22 large polyps (13 polypoid, 9 flat) and 38 medium polyps (32 polypoid, 6 flat) were detected. For large polyps observer sensitivity was 55% (polypoid 11/13 (85%); flat 1/9 (11%)) without CAD and 64% (polypoid 12/13 (92%); flat 2/9 (22%)) with CAD as second reader. For medium sized polyps observer sensitivity was 84% (polypoid 28/32 (88%), flat 4/6 (66%)) without and with CAD as second reader. The per-patient sensitivity for large polyps for the observer without and with CAD was 67% (14/21) and 76% (16/21) respectively. For polyps ≥6mm this was 81% (34/42) and 83% (35/42) respectively. The specificity of the observer for large polyps without and with CAD was 94% (110/117). For polyps ≥6mm this was 84% (81/96) without and 83% (80/96) with CAD.

Second read CAD has a positive influence on reader performance in CTC of an increased risk population. Flat lesions can be relatively prevalent in increased risk populations. This negatively influences observer performance with and without CAD in our study.

CAD for the detection of polyps in CTC in a second read paradigm enhances reader performance.

de Vries, A, Liedenbaum, M, Florie, J, Nio, Y, Truyen, R, Stoker, J, Does Second Read CAD Enhance Experienced Reader Performance in CTC of Increased Risk Individuals?.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5013247.html