MAXIMUM INTENSITY PROJECTION IMAGES IN THE DETECTION OF SIMULATED PULMONARY NODULES BY SPIRAL CT

This study was undertaken to investigate the use of maximum intensity projection (MIP) images in the detection of pulmonary nodules by spira l CT (SCT). 40 pulmonary nodules of high density were created by endob ronchial deployment of 2 and 4 mm beads in the peripheral airways of f ive anesthetized dogs. Standard SCT was performed with 5 mm collimatio n, pitch 2 and reconstruction of contiguous slices. MIP images were ge nerated from overlapped slabs of seven consecutive 3 mm slices, recons tructed at 2 mm intervals and acquired at pitch 2. Scans were reviewed by six radiologists. The data were modelled using ordinal logistic re gression for repeated measures, and the Wald chi(2) statistic used to test if there was a difference in nodule detection and reader confiden ce level between the two techniques. MIP imaging increased the odds of nodule detection by 2.18 (p = 0.0002). Reader confidence level for no dule detection was significantly higher with MIP images (p<0.00001). M IP images improve the detection rate for small high density pulmonary nodules and increase reader confidence level, when compared with stand ard SCT.