Axial 18F PET of HCC before (a) and 1 month after (b) treatment with SBRT demonstrate decreased uptake in treated tumour. Corresponding MR DWI (c, d) and ADC (e, f) sequences of the same tumour demonstrate restricted diffusion (red asterisk) in the tumour before treatment (c, e), with only minimal restriction remaining after treatment (d, f). ADC, apparent diffusion coefficient; DWI, diffusion-weighted image; HCC, hepatocellular carcinoma; SBRT, stereotactic body radiation therapy.