Whole-body simultaneous time-of-flight PET-MRI: early experience with clinical studies.

Stanford University, Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, USA Recently, a whole-body, simultaneous positron emission tomography magnetic resonance imaging (PET-MRI) system combing MRI with time-of-flight (TOF) PET has been developed. We present our initial experience with human clinical studies using 18Ffluorodeoxyglucase (FDG) with this scanner, in comparison to PET-CT. All patients underwent a single-injection of 18F-FDG, with a dual-imaging protocol consisting of PET-CT followed by PET-MRI scan. PET-MR attenuation correction used a two point Dixon fat-water separated method for the body, combined with registration to an atlas for the head. Two radiologists evaluated MRI image quality using the following scale (0 non-diagnostic; 1 poor; 2 good; 3 excellent). PET-MRI and PET-CT images were reviewed for FDG uptake thought to be consistent with malignancy by two readers independently, and categorized into 5 groups (1 both PETMRI and PET-CT positive, 2 PET-MRI positive, PET-CT positive in retrospect; 3 PET-CT positive, PET-MRI positive in retrospect; 4: PET-MRI positive, PET-CT negative; 5: PET-MRI negative, PET-CT positive) by consensus.