Thick-slice lung nodule detection: CAD prototype performance evaluation

Purpose: In many clinical situations, only thick slice CT lung studies are available due to storage, transmission or acquisition constraints. However, it is still desirable to have CAD available as a tool. Unfortunately, most commercial Lung CAD systems operate only on thin slice (< 2.5mm) input data. We evaluate the detection capability of a prototype thick slice Lung Nodule CAD system. Methods and Materials: The system was evaluated using 131 unseen cases, from institutions in the United States and Europe, using various vendor?s scanners. Group 1 (G1, n=60) included cases from Siemens? scanners (VolumeZoom=12, Sensation16=31, Sensation64=17) at 5mmq5mm. Group 2 (G2, n=35) with cases from Philip?s scanner (Mx8000 16) at slice thickness 6.5mmq5mm slice interval. Group 3 (G3 n=36) with cases from GE?s scanner (LightSpeed 16) at 5mmq5mm. The prototype?s performance was evaluated on all nodules with diameter range 6-25mm. Group G1 had 42 solid and part-solid pulmonary nodules, G2 had 40 and G3 had 59. Results: For G1, per-nodule sensitivity was 90.4% with an average FP of 4/case. For G2 per-nodule sensitivity was 72.5% with an average FP of 3.05/case and for G3 per-nodule sensitivity was 78% with average FP of 2/case. Conclusion: The prototype generalized across scanners from multiple vendors, models, and different sites. The system has the potential to extend the practical range of acquisition data over which Lung CAD may be applied to help overcome existing constraints on CAD utilization.