Recommendations of the imaging committee of the International Harmonization Project (IHP) for FDG-PET (PET) use in patients with lymphoma

1681 Objectives: International guidelines for PET use in lymphoma are desirable to standardize PET imaging and interpretation in clinical practice and compare results among studies. The IHP was convened to discuss harmonization of clinical trial parameters in lymphoma. Six committees were formed, including imaging. We present the imaging committee’s recommendations endorsed by the IHP. Methods: These recommendations were based on published PET literature. Consensus was reached regarding controversial points. Results: PET should be routinely used for response assessment at the conclusion of therapy (tx) in pts with Hodgkin Lymphoma (HL) and diffuse large B-cell lymphoma (DLBCL), in which case a pretreatment PET is strongly encouraged but not required for response assessment as these lymphomas are routinely FDG-avid. In contrast, pretreatment PET is mandatory for variably FDG-avid (VA) aggressive NHLs if PET is used to assess response. PET should only be used for response assessment of indolent NHL and mantle cell lymphoma (MCL) if response is a major endpoint in a clinical trial, in which case a pretreatment PET is strongly encouraged but not mandatory in MCL and follicular lymphoma (FL) but required for all other indolent NHLs. For all VA NHL histologies, PET should only be used to assess response if positive prior to tx. PET at tx conclusion should not be performed prior to 3 wks post-chemo-/chemoimmunotherapy, preferably at 6-8 wks, and 8-12 wks post-radiation/chemoradiation. Visual assessment alone is adequate for interpreting PET findings as positive/negative when assessing response at tx conclusion. Non-attenuation-corrected PET is acceptable for response assessment but is discouraged in favor of attenuation-corrected PET. “Mid-tx” PET, performed after 1-4 cycles of chemotherapy, should only be done in a clinical trial. There is currently no justification for PET as routine post-tx surveillance. Conclusions: We recommend these guidelines be adopted by the imaging community to facilitate patient care and comparison among studies.