Quantitative Cancer Imaging using Standard-of-Care PET/CT Outside the Clinical Trial Setting: A 5-year Compliance Assessment Review of Longitudinal Technical Reproducibility for PERCIST Criteria

Objectives: Reproducibility in the imaging of tumors and tissues is important in quantitative cancer imaging. As such, quantitative imaging criteria and guidelines have been proposed to limit variations within and between tumor imaging protocols, with the aim of improving accuracy and precision in treatment response assessment using FDG-PET/CT. A review of Department of Imaging records found high feasibility of meeting the PET Response Criteria in Solid Tumors (PERCIST) technical parameters for quantitative imaging during longitudinal standard-of-care FDG-PET/CT exams in an oncologic patient population. This exhibit discusses the department practices required to achieve compliance to PERCIST.

Methods: All research was performed under approval of the Dana-Farber Cancer Institute (DFCI) institutional review board. The records of all adult patients undergoing FDG-PET/CT tumor imaging exams at DFCI Department of Imaging from 2010 through 2016, were retrospectively reviewed and evaluated for compliance with PERCIST criteria for technical parameters, such as fasting status, plasma glucose level, injected activity and uptake time. These parameters were documented on the patient screening forms and transcribed to an electronic database. Some parameters were also recorded in the patient’s electronic medical records and in the DICOM metadata of the FDG-PET/CT images in the radiology picture archives (PACS).Review of the electronic database found records for ~5,000 patients undergoing two or more FDG-PET/CT exams during a five-year period after the publication of PERCIST. For each patient, the first FDG-PET/CT exam recorded during the period was considered the “baseline” for evaluating compliance with the PERCIST criteria. The median time between the baseline and all subsequent FDG-PET-CT exams was 308 days, while the median time between consecutive FDG-PET/CT exams was 128 days.

Results: The key contributors to achieving high compliance were found to include the screening by front desk staff the day prior to the patient visit, the technologist workflow during patient preparation, the longitudinal record keeping of the technical parameters using the screening forms as part of the patient record, the calibration of the camera equipment, and consistent acquisition and reconstruction protocols. Glucose cutoff and injected activity are set by departmental policies, while the acquisition and reconstruction parameters are by pre-set camera protocols. Additionally, technologist workflow and standard practice routinely included reviewing the screening forms and PACS records from the patient’s prior FDG-PET/CT exams in order to match all the parameters as best as possible during the current exam.The PERCIST criteria for fasting status, plasma glucose levels, injected activity and uptake time during baseline and follow-up FDG-PET/CT exams was met at a 76% level (13,277 of 17,547 visits for 4,135 of 4,859 patients). However, during the period under review, dose reduction policy changes to the standard-of-care imaging protocols reduced the “standard dose” from 20 mCi ±10% to 14 mCi ±10% for adult patients undergoing FDG-PET/CT exams, which resulted in a 30±14% decrease in injected activity that was expected to exceed the PERCIST cutoff. When the analysis was limited to only those visits after the FDG dose policy changes, 92% of FDG-PET/CT studies (11,656 of 12,706 visits for 3,516 of 3,707 patients) met the PERCIST criteria.

Conclusion: Quantitative imaging can be performed with highly reproducible technical parameters for longitudinal clinical standard-of-care imaging outside of the clinical trial setting and research environments. A team effort is required to achieve this goal, including close collaboration between technologists, front-desk staff, nurses, nuclear medicine physicians, and physicists. Research Support: None