On the Quantification Accuracy, Homogeneity, and Stability of Simultaneous Positron Emission TomographyMagnetic Resonance Imaging Systems

A potential major application of simultaneous avalanche photodiode–based positron emission tomography (PET)magnetic resonance imaging (MRI) systems are quantitative brain studies for cerebral blood flow measurements in combination with blood-oxygen-level–dependent or perfusion MRI, requiring a high performance for both modalities. Thus, we evaluated PET quantification accuracy and homogeneity for 2 different simultaneous PETMRI systems (whole–body and brain scanner) compared with those of a state-of-the-art PET detector (PETcomputed tomography) using phantom studies. In addition, we investigated the long-term stability of PET and quality of functional MRI measurements of a clinical whole-body PETMRI scanner.