Although CT remains the gold standard for the staging and follow-up of malignant lymphomas, 18F-FDG PET has a potential role in accurately staging disease and in predicting response to therapy. This role has the potential to affect both the initial choice of chemotherapy and the decision to alter management based on the initial response to therapy . PET performed early in a chemotherapeutic regimen has demonstrated a role in identifying patients who will experience relapse and may require further treatment, but attention to the timing of the scan in relation to chemotherapy and growth factors is crucial. Many studies have used subjective grading systems to assess response and have evaluated progression-free survival on the basis of negative or positive findings on follow-up scans. Further studies should focus on measuring response on the basis of SUV: Determining a cutoff value when assessing the percentage of change in SUV may improve the prognostic value of interim PET. Because most studies have shown variable SUVs among both aggressive and indolent lymphomas, the usefulness of a follow-up scan hinges on the existence of a pretherapy scan demonstrating 18F-FDG–avid disease. The role of 18F-FDG PET for indolent lymphomas, like CLL, remains unclear, and further studies have to be designed to investigate the role of PET for specific histologic types. NCCN (p.127) recommends PET for restaging of large cell lymphoma.
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Yuliya S. Jhanwar and David J. Straus The Role of PET in Lymphoma Journal of Nuclear Medicine Vol. 47 No. 8 1326-1334, 2006
Bruce D. Cheson MD, Non-Hodgkin’s Lymphomas: New Insights and Therapeutic Strategies
Staging and Evaluation of the Patient with Lymphoma
Hematology/Oncology Clinics of North America
Volume 22, Issue 5, October 2008, Pages 825-837