Combined value of apparent diffusion coefficient-standardized uptake value max in evaluation of post-treated locally advanced rectal cancer

Figure 1 A 72-year-old man with pathologically proven proximal rectal cancer, classified as non-responder after chemoradiation treatment. A: Pre-CRT T2-weighted axial MR image shows a circumferential pathological rectal mass, with largest thickening from 12 to 6 o’clock position, narrowing rectal lumen and with corresponding mesorectal fat spread around; B: Post-CRT T2- weighted axial MR image shows incomplete decrease in rectal wall thickening, with irregular and inhomogeneous neoplastic tissue still determining lumen narrow; C: Pre-CRT DWI image shows the presence of hyperintense area at the corresponding level of tumor mass (ADC: 0.63 × 10^-3 mm²/s); D: Post-CRT DWI image demonstrated partial response, with focal hyperintense area still detectable (ADC: 1.25 × 10^-3 mm²/s); E: Pre-CRT axial pelvic scan examination image demonstrates a significant radiotracer uptake in the hight rectum, corresponding tumor region (SUVmax: 19.4); F: The partial metabolic response is also confirmed by CRT PET/CT scans, in particular a significant tumor uptake is still present (SUVmax: 4.3). CRT: Chemoradiation treatment; DWI: Diffusion weighted imaging; ADC: Apparent diffusion coefficient; SUV: Standardized uptake value.