A 67-year-old male (Case 1) and (c, d) a 40-year-old female (Case 2) were pathologically confirmed as having MT-IP and IP, respectively; (b, d) the whole-tumour ROIs of ADC were delineated by referral to (a, c) contrast-enhanced T
1 weighted imaging; (e) two ADC histograms were acquired based on the ROIs, and a lower ADC10th (0.68 × 10−3 mm2/s vs 1.01 × 10−3 mm2/s) and higher ADC Skewness (0.92 vs 0.29) were shown in Case 1, compared with Case 2. ADC, apparent diffusion coefficient; IP, inverted papilloma; MT, malignant transformation; MT-IP, inverted papilloma with malignant transformation; ROIs, regions of interest.