Baseline pre-therapy axial (a) and coronal images (b) in a 66 year old patient with stage III DLBCL and a 13.7 cm mesenteric mass denoted with arrows. After 6 cycles of R-CHOP, a 6.3 cm residual mass persisted with nodular foci of uptake (SUV of 13.2 and 12.4), including one focus of activity that was new since the interim pet-ct scan (c, d). The patient was treated with IMRT to a final dose of 42 Gy (e, f). Restaging PET-CT three months following completion of RT revealed complete resolution of the FDG avid foci in a decreased mesenteric mass of 5.5 cm (marked with arrows) (g, h).