Validation of standardized uptake values for [18F] FDG in 112 lesions at 6 individual organ systems: Comparison of whole-body PET/CT and PET/MRI

Objectives A recently commercialized integrated PET/MRI has raised intense clinical interest [1-2]. For the clinical applications, especially in oncological indications, the validation of the semi-quantitative measurement (SUVmax) from PET/MRI is essential [3-4]. Therefore, a comparative study between PET/MR and PET/CT was performed to evaluate whether PET/MR could provide a comparable SUVs to that acquired by PET/CT in clinically confirmed FDG-avid lesions at 6 individual organ systems, including head & neck, lung, liver, gastrointestinal system, pancreas and skeletal system.

Methods 150 subjects with various malignancies underwent a single-injection/dual-imaging, IRB approved protocol, consisting of a PET/CT and subsequent PET/MR scan. PET/MR using a sequence combination of T1WI 3D-VIBE, T2WI TSE with fat saturation, DWI with double b values (50 and 800s/mm2), and simultaneous PET acquisition over 45min/5 bed positions. Volumes of interest (VOIs) were drawn over FDG-avid lesions in both MRI based attenuation corrected PET (MRAC-PET) and the corresponding CT based attenuation corrected PET (CTAC-PET) images manually. Pearson correlation analysis and Wilcoxon-Matched-Pairs signed ranks test were used to assess the lesions’ SUVmax derived from PET/CT (SUVmax_CT) and PET/MR (SUVmax_MRI) at various locations.

Results 112 lesions at 6 organs were detected in 150 subjects, including 96 malignant and 7 benign lesions (pathologically confirmed), and 8 malignant and 1 benign lesions (clinical evidence indicated). A strong correlation of SUVmax between PET/CT and PET/MR was observed in six organ systems (R: 0.91 ~ 0.97, Figure 1.). Although no significant difference was detected for lesions in each organ system, the biggest data deviation was found in the lung.

Conclusions PET/MR can provide comparable and feasible measurements as those provided by PET/CT for whole-body examinations.

Research Support This study was financially sponsored by the National Natural Science Foundation of China (grant 30670586, 30900352, 30970770, 30571600 and 60831004),the China Postdoctoral Science Foundation (grant 20090461433) and the Hundred Talents Program of the Chinese Academy of Sciences.