PERCIST CRITERIA

     In PERCIST criteria, response to therapy in solid tumors is assessed as a continuous variable and expressed as percentage change in SUL (standarized uptake normalized to lean body mass) peak (or sum of lesion SULs) between the pre- and posttreatment scans.

     Complete metabolic response is defined as visual disappearance of all metabolically active tumor.

     Partial response is considered more than a 30% and a 0.8-unit decline in SUL peak between the most intense lesion before treatment and the most intense lesion after treatment, although not necessarily the same lesion.

     More than a 30% and 0.8-unit increase in SUL peak or new lesions, if confirmed, is classified as progressive disease. A greater than 75% increase in total lesion glycolysis is proposed as another metric of progression.

     Richard L. Wahl, Heather Jacene, Yvette Kasamon and Martin A. Lodge. From RECIST to PERCIST: Evolving Considerations for PET Response Criteria in Solid TumorsJ Nucl Med 2009; 50:122S–150S.

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