Fig. 1

PI-RADS™ v2 assessment categories: Fig. 1a depicts typical findings in the peripheral zone and Fig. 1b depicts typical findings in the transition zone. a. Peripheral zone shows PI-RADS assessment categories with DWI as dominant sequence. 1. No abnormality (i.e. normal) on the high b-value DW image and on the corresponding ADC map as well as on the T2w image. 2. Isointense signal of the peripheral zone on the high b-value DW image with an indistinct linear hypointense lesion on the ADC map (arrow) with corresponding T2w hypointense signal. 3. Isointense/mildly hyperintense signal of the peripheral zone on the high b-value DW image and with a focal mildly/moderately hypointense indistinct lesion on the ADC map (arrow). T2w image shows heterogeneous signal intensity of the peripheral zone. 4. Focal markedly hyperintense lesion on high b-value DW image with corresponding markedly hypointense signal intensity on the ADC map (arrow). Lesion size is < 1.5 cm on axial images. T2w image shows a circumscribed homogenous hypointense lesion. 5. Same as 4, but lesion size is ≥ 1.5 cm in greatest dimension (arrow). Definite extraprostatic extension/invasive behaviour (not shown) would also qualify for this category. b Transition zone shows PI-RADS assessment categories with T2w as dominant sequence: 1. Homogeneous intermediate signal intensity (normal) on T2w image and no abnormality on high b-value DW image and ADC map. 2. Circumscribed (arrows) hypointense or heterogeneous encapsulated nodule(s) (BPH). High b-value DW image shows normal signal intensity and indistinct hypointense signal on ADC map. 3. Lesion with heterogeneous signal intensity with obscured margins (arrow). High b-value DW image of the lesion is mildly hyperintense and moderately hypointense on the ADC map. This category includes lesions that do not qualify as 2, 4, or 5. 4. Lenticular (arrow) or non- circumscribed, homogeneous, moderately T2w hypointense lesion, < 1.5 cm in greatest dimension. High b-value DW image of the lesion shows markedly hyperintense signal and markedly hypointense signal on the ADC map. 5. Same as 4, but lesion size is ≥ 1.5 cm in greatest dimension (arrows). Definite extraprostatic extension/invasive behaviour (not shown) would also qualify for this category