Reproducibility and repeatability of same-day two sequential FDG PET/MR and PET/CT

Area of Science:

• Nuclear Medicine
• Radiology
• Oncology

Background:

• Assessing the reproducibility and repeatability of fluorine 18 fluorodeoxyglucose (FDG) uptake measurements is crucial for cancer patient management.
• Standardized uptake values (SUV) and lean body mass (SUL) are key metrics in PET imaging.

Purpose of the Study:

• To determine the reproducibility of PET/CT versus PET/MR and the repeatability of PET/MR for FDG uptake measurements in tumors.
• To evaluate the clinical acceptability of these imaging modalities for assessing treatment response.

Main Methods:

• Prospective study involving 33 cancer patients with visible tumors, performing same-day PET/CT and two sequential PET/MR scans.
• Calculated SUV, SUL, metabolic tumor volume (MTV), and tumor-to-liver ratio (T/L) using a 40% threshold.
• Utilized Bland-Altman analysis to assess agreement, with ±30% defined as the maximal acceptable limit.

Main Results:

• Strong positive linear correlations were observed between PET/CT and PET/MR, and between sequential PET/MR for lesional SUV, SUL, and MTV.
• PET/MR demonstrated good repeatability for SUVpeak and SULpeak, with 95% limits of agreement within ±17.9%.
• Other PET metrics showed agreement outside the ±30% clinical acceptability range between PET/CT and PET/MR, and between sequential PET/MR.

Conclusions:

• PET/MR exhibits clinically acceptable repeatability for SUV/L peak measurements in cancer patients.
• PET/MR is a viable option for evaluating treatment response due to its reliable repeatability.