Metabolic parameters on [ 18 F]fluoro-2-deoxy- d -glucose PET/MRI: feasibility study comparing standardized uptake...

[ 18 F]fluoro-2-deoxy-D-glucose ([ 18 F]FDG)-PET/MRI is a 'one-stop-shop' combination that enriches lesion characterization, locoregional and distant staging in breast cancer patients. The combination consists of a breast (bpPET/MRI) and whole-body (wbPET/MRI) within a single protocol. Despite acceptable test-retest reproducibility of standardized uptake value (SUV) in PET examinations being 10%, limited knowledge concerning agreement between metabolic parameters from each protocol (bpPET/MRI and wbPET/MRI) is available.

Feasibility study to verify whether differences of metabolic parameters in breast tumor, on prone bpPET/MRI acquired between 30 and 55 min postinjection, and compared to wbPET/MRI at 60 min, remained within the 10% margin acceptable in clinical practice.

Breast cancer patients underwent [ 18 F]FDG-PET/MRI: bpPET/MRI and wbPET/MRI. Maximum SUV (SUVmax) and mean SUV (SUVmean) measurements of the index tumor, contralateral breast, liver, and blood pool were obtained from bpPET/MRI images acquired every 5 min between 30 and 55 min. These values were compared with wbPET/MRI SUVs at 60 min (reference).

Twenty patients were included. The majority of PET/MRI exams remained within the 10% margin at all timepoints. At 45 and 50 min the mean percentage difference of SUVmax and SUVmean compared to 60 min was less than 1.3-3.6%. Other SUV measurements remained within 10% margin in majority of cases, while bloodpool SUVs did differ.

Metabolic parameters for local staging in the index tumor on bpPET/MRI may be considered comparable to the metabolic parameters retrieved from wbPET/MRI in breast cancer patients. These findings reinforce the potential of a breast-dedicated protocol integrated in the whole-body [ 18 F]FDG PET/MRI in breast cancer patients.