Hepatic 18F-FDG Uptake Measurements on PET/MR: Impact of Volume of Interest Location on Repeatability.

Background: To investigate same day 18F-FDG (Fluorodeoxyglucose) PET (Positron Emission Tomography)/MR (Magnetic Resonance) test-retest repeatability of Standardized Uptake Value measurements normalized for body weight (SUV) and lean body mass (SUL) in different locations in the liver. Methods: This prospective study was IRB approved with written informed consent obtained. 35 patients (20 women and 15 men, 61 ± 11.2 years) that performed a whole-body 18F-FDG PET/MR followed by liver-dedicated contrast-enhanced 18F-FDG PET/MR were included. SUV/L max, mean, and peak were measured inferior to, superior to, and at the right portal vein and in the left lobe of the liver. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated and Bland-Altman plots were obtained. Results: The variability for SUV/L's measurements was lowest inferior to the portal vein (<9.2%) followed by measurements performed at the level of the portal vein (<14.6%). Conclusion: The area inferior to the portal vein is the most reliable location for hepatic 18F-FDG uptake measurements on PET/MR.