Qualification of NCI-designated comprehensive cancer centers for quantitative PET/CT imaging in clinical trials

Objectives Quantitative PET/CT imaging can provide early assessment of tumor response at a molecular level, thereby enabling more objective, efficient, and accurate trials of new therapeutic agents. The primary objective of the Centers of Quantitative Imaging Excellence (CQIE) project, run by the American College of Radiology Imaging Network (ACRIN), is to establish sites within the NCI Cancer Center Program that are capable of conducting clinical trials in which there are integral molecular and/or functional advanced imaging endpoints.

Methods An imaging test suite was developed based on existing ACRIN and ACR protocols. These included SUV measurements, axial uniformity, and contrast ratio tests using uniform cylinders and the ACR phantom. Dynamic imaging tests were also included.

Results A total of 59 NCI Cancer Centers were contacted, and 56 agreed to participate. There were 64 PET/CT systems tested (GE: 6 models and 36 scanners, Siemens: 7 models and 21 scanners, Philips: 3 models and 7 scanners). All systems achieved CQIE certification: 25 systems passed on first attempt, 30 required two attempts, 9 required 3 or more attempts. Reasons for failure were: Quantitative errors (21), incomplete data or forms (15), and incorrect protocols (13). After CQIE certification, SUVs for a uniform cylinder were 1.00±0.03 for body imaging protocols and 0.99±0.04 for brain imaging protocols. Axial variation in uniform cylinders was 5.3% and 3.7% for body and brain imaging protocols.

Conclusions Over half (39/64) of the PET/CT scanner required testing more than once to achieve CQIE certification, with quantitative errors being the most common failure mode. In some cases scanner re-calibration corrected the quantitative errors. After CQIE qualification, SUV and axial uniformity values were within acceptable levels for clinical trials using quantitative PET imaging.

Research Support Supported in part by NCI-SAIC Subcontract #10XS070.