Fig. 3From: Differentiation of renal angiomyolipoma without visible fat from small clear cell renal cell carcinoma by using specific region of interest on contrast-enhanced CT: a new combination of quantitative toolsThe placement method of ROI (3). a–d are EP, PCP, CMP and NP images, respectively: firstly, the tumor boundary should be determined in EP, and ROI (red) should cover the entire range of tumor as much as possible, with its edge 2–3 mm away from the tumor's edge; secondly, ROI of the same size should be placed in PCP, CMP and NP according to the location of ROI in EPBack to article page