Multicenter Harmonization of Zr-89 PET/CT Performance

This study investigated the feasibility of quantitative accuracy and harmonized image quality in Zr-89-PET/CT multicenter studies. Methods: Five PET/CT scanners from 3 vendors were included. Zr-89 activity was measured in a central dose calibrator before delivery. Local activity assays were based on volume as well as on the local dose calibrator. Accuracy and image noise were determined from a cross calibration experiment. Image quality was assessed from recovery coefficients derived from different volume-of-interest (VOI) methods (VOIA50%, based on a 3-dimensional isocontour at 50% of the maximum voxel value with local background correction; VOImax, based on the voxel with the highest uptake; and VOI3Dpeak, based on a spheric VOI of 1.2-cm diameter positioned so as to maximize the enclosed average). PET images were analyzed before and after postreconstruction smoothing, applied to match image noise. Results: PET/CT accuracy and image noise ranged from -3% to 10% and from 13% to 22%, respectively. VOI3Dpeak produced the most reproducible recovery coefficients. After calibration of the local dose calibrator to the central dose calibrator, differences between the local activity assays were within 6%. Conclusion: This study showed that quantitative accuracy and harmonized image quality can be reached in Zr-89 PET/CT multicenter studies.