Detection of pulmonary nodules at spiral CT: comparison of maximum intensity projection sliding slabs and single-image reporting

The aim of this study was to compare numbers of pulmonary nodules detected with maximum intensity projections using a slab thickness of 15 mm. (MIP 15 ) and 30 mm (MIP 30) with single image (SI) presentation of chest CT scans. Two readers reviewed MIP 15, MIP 30, and SI presentations of 10-mm (n = 8) and 5-mm collimation (n = 10) helical CT scans and recorded size, location , and diagnostic confidence (definite, probable) of pulmonary nodules. Read ers 1 and 2 recorded more nodules with MIP 15 than with SI: 10-mm collimati on, 77/64 and 60/56; 5-mm collimation, 64/60 and 40/36; and more "definite" nodules (10-mm. collimation: 68/57 and 51/42; 5-mm collimation: 43/36 and 34/30). MIP 15 also detected more nodules than MIP 30 at 10-mm collimation: 77/72 and 60/50; with no major differences at 5-mm collimation: 64/66 and 40/38; and more "definite" nodules (10-mm collimation: 68/58 and 51/36; 5-m m collimation: 43/39 and 34/29). There were only minor differences between SI and MIP 30. Reading time and image number per study were reduced with MI P presentations by a factor of 1.4-5-3. There were no significant differenc es in the number of nodules detected with SI, MIP 15, and MIP 30, but MIP p resentation reduced reporting time and filming cost when compared with SI r eporting. For detection of nodules MIP 15 was slightly superior to MIP 30.