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 tools

Figures

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  Fig. 1. Flowchart of patient inclusion and exclusion

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  Fig. 2. The placement method of ROI (1) and ROI (2). a and b are schematic diagram of blood-rich supply region in the tumor: significantly enhanced region was observed as small patches with unclear boundary at the edge of tumor's parenchyma (red arrow), while tumor vessels presented an arc-shaped linear structure (yellow arrow). (c) is definition method of ROI (1) and ROI (2) based on (a): red ROI is ROI (1), and yellow ROI is ROI (2)

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  Fig. 3. The 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 EP

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  Fig. 4. Schematic diagram of the morphological features of ccRCC and AML.wovf. a, a 70-year-old male with histopathologically proven ccRCC. Pseudocapsule sign is shown as a low attenuation ring at the edge of tumor (red arrow). b, a 57-year-old male with histopathologically proven ccRCC. Cystic degeneration is observed in the central area of tumor (yellow arrow). c, a 49-year-old female with histopathologically proven AML.wovf. Angular interface with an angle less than 90° is observed between the tumor and the surrounding tissue (blue arrow)

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  Fig. 5. Receiver operating characteristic curves for the prediction models based on four scanning phases

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  Fig. 6. Using CMP images to distinguish AML.wovf from ccRCC. a, CMP imaging of a 59-year-old male with histopathologically proven ccRCC. Main quantitative parameter: AVT_CMP (1) = 188.93 Hu, RER_CMP (1) = 92.38, AVT_CMP (2) = 236.74 Hu, RER_CMP (2) = 115.76, HDT_CMP = 43.62 Hu, SHR_CMP = 369.35. b CMP imaging of a 55-year-old male with histopathologically proven AML.wovf. Main quantitative parameter: AVT_CMP (1) = 157.75 Hu, RER_CMP (1) = 84.22, AVT_CMP (2) = 179.96 Hu, RER_CMP (2) = 96.08, HDT_CMP = 24.29 Hu, SHR_CMP = 223.46. Generally, it is difficult to distinguish AML.wovf from ccRCC by using only one conventional ROI [ROI (1)] in CMP. However, combining a smaller ROI [ROI (2)] representing the enhancement degree and a larger ROI [ROI (3)] representing the degree of enhanced heterogeneity together can accurately distinguish them in single CMP