In Multiple Myeloma (MM) patients, both magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) proved to be reliable imaging techniques to detect bone lesions and bone involvement at diagnosis [1]. Fully integrated PET/MR systems, combining these two methodologies, need dedicated MR-based attenuation correction (MRAC) of PET data which is still objective of ongoing research. A variety of MRAC approaches for whole-body studies have been proposed so far and can be classified as template-based methods [2, 3], atlas-based methods [4], direct-segmentation approaches [5–8] and methods...

Patient population 30 patients (M=18, F=12; mean age: 61 ± 10 yo; age range 44 - 79 years) who underwent18F-FDG PET/MR scans for MM staging (15/30) or post-therapy follow up (15/30) from March to December 2018 at the Nuclear Medicine Department of University-Hospital in Padua were considered for the present study. Acquisition protocol A standardized 18F-FDG PET protocol according to EANM [16] was followed: meaninjected activity was 220 ±38 MBq, mean post-injection uptake time was 71 ±23 minutes, the number of beds (3 minutes each)...

No bone lesions were missed on visual inspection in any of the PET images, regardless of the inclusion of bone-modeling algorithm for attenuation correction (Table 1). Bone modeling errors were visually evident in 13/30 (43%) and 20/30 (67%) DIXONstd and DIXON-CAIPI based μ-maps, respectively (Table 2, Fig. 1). Regardless of the MR sequences used for μ-maps generation (DIXONstd/DIXON-CAIPI), a statistically significant, but slight, increase in background regions SUVmean was determined by bone compartment addition (p < 0.01). Statistically significant higher SUVmean values were observed in...

In the present study, the introduction of a model-based bone-compartment to the standard MR-based μ-map, currently used for PET AC in Siemens Biograph mMR, determined a limited effect on background regions SUVmean and bone lesions SUVpeak of reconstructed PET data, regardless of the MR sequences used as input data. Despite statistical significance of SUV differences in bone background regions and bone lesions, their magnitude did not influence the visual interpretation of PET images on any of the studied patients. Considering thenumber of bone modelization errors...

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