Fig. 1.

An 82-year-old man with rectal adenocarcinoma. Axial T2-weighted SPACE image (a), fused ¹⁸ F-FDG PET and axial T2-weighted SPACE images (b), b1000 diffusion image (c), and ADC map (d) all acquired by hybrid PET/MR. ADC value was measured by drawing a freehand ROI along the high signal intensity tumor border on a single slice b1000 image containing the largest tumor area (c). The ROI was copied to the ADC map (d) to calculate the ADCmean. ADC map was automatically generated in grayscale by the operating system, using a mono-exponential decay model