RADIOLOGY: ABDOMEN: Case# 15: LOW GRADE MALIGNANT LYMPHOMA - PERIAORTIC MANTLE & MESSENTERIC NODES. Abdominal mass. Marked splenomegaly and a small amount of ascites are present. Extensive abdominal and pelvic adenopathy with a mantle of adenopathy surrounding the aorta, inferior vena cava and ureters. This adenopathy extends into the pelvis and involves both iliac regions. Mesenteric, retrocrural and celiac chain adenopathy is noted. There is mild hydronephrosis on the right. Both CT and MR can be used to monitor post-chemotherapy response in lymphoma. Though CT can be accurate in assessing tumor regression and relapse within new nodal groups, the ability to distinguish between residual tumor and sterilised fibrotic masses is limited. Residual soft-tissue masses have been reported in upto 50% of the patients, most commonly with nodular sclerosing type of Hodgkins disease, and more commonly when the pretreatment mass is large. MR is helpful in these circumstances as appearance of high signal on T2 images more than 6 months after treatment suggests recurrence.