FDG PET CT assessment of treatment response after yttrium-90 ibritumomab tiuxetan radioimmunotherapy

Yttrium-90 ibritumomab tiuxetan (Zevalin; IDEC Pharmaceuticals Corp., San Diego, CA) is the first radioimmunotherapy agent approved by the U.S. Food and Drug Administration (FDA) for treatment of non-Hodgkin lymphoma. In a randomized clinical trial comparing Zevalin with rituximab, the overall response rate was 80% and 56%, respectively. Response was determined by assessing the size of lymph nodes on CT scans. FDG PET has been well accepted as an accurate imaging study for staging non-Hodgkin lymphoma and evaluating response to treatment. Simultaneous FDG PET and CT imaging (PET CT) provides coregistered functional PET images with anatomic CT images. We describe 2 cases of non-Hodgkin lymphoma treated in which response was followed using PET CT. Copyright © 2005 by Lippincott Williams & Wilkins