Antonella Lostumbo MD, Presenter: Nothing to Disclose

Abraham H. Dachman MD, Abstract Co-Author: Consultant, E-Z-EM, Inc Consultant, iCAD, Inc Research support, iCAD, Inc Consultant, General Electric Company Research support, Koninklijke Philips Electronics NV

Kenji Suzuki PhD, Abstract Co-Author: Research grant, Riverain Medical Research grant, Hitachi, Ltd License agreement, Riverain Medical License agreement, MEDIAN Technologies Research Consultant, Riverain Medical Royalty distribution as research fund, Riverain Medical Royalty distribution as research fund, MEDIAN Technologies Royalty distribution as research fund, Hologic, Inc Royalty distribution as research fund, General Electric Company Royalty distribution as research fund, Toshiba Corporation Royalty distribution as research fund, Mitsubishi Corporation

Joy Tsai MD, Abstract Co-Author: Nothing to Disclose

Christian Wanamaker MD, PhD, Abstract Co-Author: Nothing to Disclose

Flat lesions in the colon are a potentially major and controversial source of false-negative CT colonography (CTC) interpretations. There are no clinical data to indicate whether flat lesions are more likely to be detected on two-dimensional (2D) or three-dimensional (3D) images and which 2D window and level settings are optimal. We sought to study the effect of these factors to determine which method is optimal for detection of flat lesions.

Cases were selected from a previously published clinical trial. Eighty-eight lesions in 66 patients were analyzed. All lesions were viewed in 2D at three window/level settings and in 3D endoluminal view. In each view, the long axis and height were measured. Criteria of “height” (< 3mm high) or “ratio” (height < ½ long axis) were applied. A subset of lesions was subject to inter- and intra-observer variability analysis.

A lesion may be defined as flat in one viewing method, but not another and this difference is significant among all four viewing methods. If long axis is used as a key metric to characterize lesions, there is a statistically significant difference between lung or soft tissue versus 3D viewing. Endoluminal 3D viewing showed the least inter-observer variability. Intra-observer variability was low overall for all methods.

When characterizing lesions as flat, a consistent viewing method should be used. To minimize inter-observer variability (such as when following a patient over time) it is best to use the single longest dimension as seen on 3D view as the key metric.

To minimize inter-observer variability (such as when following a patient over time), we propose that it is best to use the single longest dimension as seen on 3D views as the key metric.

Lostumbo, A, Dachman, A, Suzuki, K, Tsai, J, Wanamaker, C, Comparison of 2D and 3D Views for Measurement and Conspicuity of Flat Lesions in CT Colonography.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6016552.html