November 9, 2010 – In an effort to further promote the utility of PET/CT (positron emission tomography/computed tomography) imaging in assessing the effectiveness of oncology treatments, a new quantification tool is available to support PERCIST (PET response criteria in solid tumors). PERCIST provides standard uptake value (SUV)-based metrics to define response criteria designed to complement the standard Response Evaluation Criteria in Solid Tumors (RECIST) criteria.
Since the introduction of PERCIST, Siemens Healthcare Molecular Imaging created a PET/CT quantification tool to aid in the adoption of PERCIST evaluation criteria. Using a consistent PET protocol and fixed small region of interest, Siemens’ quantification tool evaluates the most active region of a metabolically active tumor to minimize statistical variability and offer the most consistent results. Siemens supports industry initiatives with this software tool that will make PERCIST data available and reproducible for every patient, so that these criteria will be clinically adopted and used in the field.
RECIST is a well established set of rules for determining response to therapy for patients. These criteria were formed on the basis of measuring anatomical changes in tumors using CT imaging. Because PET/CT imaging can detect changes to the tumor at the molecular level, thought leaders in the molecular imaging field introduced PERCIST criteria to use together with RECIST.
While RECIST criteria offer quantifiable data in terms of tumor size, the PERCIST quantification tool creates reproducible, objective results based on metabolic information for tumor trending over time to determine the efficacy of treatment. PERCIST criteria allow treatment response to be measured in the absence of anatomic change through the assessment of metabolic activity, often even before anatomical changes take place. The PERCIST quantification tool evaluates and delineates metabolic information from the tumor. The tool uses an algorithm that automatically identifies peak SUV within a volume of interest, rather than the common single-pixel measure of SUVmax. The PERCIST quantification tool offers a more robust metric that is less susceptible to statistical variation and noise.
For more information: www.siemens.com/healthcare
October 23, 2025 
