To assess the added value of a prototype CAD system for PE in contrast-enhanced multi-detector CT images

C.M. Schaefer-Prokop, O.M. van Delden, H. Bouma, J.J. Sonnemans, F.A. Gerritsen and J.S. Lameris. To assess the added value of a prototype computer-aided detection (CAD) system for pulmonary embolism (PE) in contrast-enhanced multi-detector computed tomography (CT) images, European Congress of Radiology (ECR), No. B-584, Mar. 2006.

Abstract

Purpose: To assess the added value of a prototype computer-aided detection (CAD) system tor pulmonary embolism (PE) in contrast-enhanced multi-detector computed tomography (CT) images.
Methods and Materials: Datasets used for training of the CAD system (n = 20) and evaluation (n = 13) were obtained with a 4-slice scanner with a pixel size of 6 mm, a spacing between slices of 0.6 mm and a slice thickness of 1.3 mm. The study group consisted of 13 CTPA studies with a mean number of 4 thrombi (Range 1-10). Datasets were selected to demonstrate a variety of thrombus load. Considerable breathing artifacts (n = 2), sub-optimal contrast (n = 1) and additional parenchymal disease (n = 6). One experienced radiologist was asked to annotate all thrombi. The most proximal location of the thrombus defined its anatomic classification (main, lobar, segmental or sub-segmental), the thrombus size defined its conspicuity (obvious, medium or subtle).
Results: Without CAD, the radiologist annotated 37 emboli located in the main (n = 7), lobar (n = 6), segmental (n = 14) and sub-segmental arteries (n = 10). With CAD, 12 additional thrombi were detected (increment of 32%), located in segmental (n = 2/16, 12%) and sub-segmental arteries (n = 10/20, 50%). Thrombi additionally detected by CAD were classified as being of subtle conspicuity (9/12, 75%) or medium conspicuity (3/12, 25%). Per dataset the CAD system showedon average 8.7 false positive calls (median = 7).
Conclusion: Compared to the radiologist, the prototype CAD system found additional emboli in segmental and sub-segmental arteries. These preliminary resultssuggest that CAD may become a helpful tool for diagnosing low grade acute pulmonary embolism in peripheral arteries.