Quantitative bone marrow magnetic resonance imaging through apparent diffusion coefficient and fat fraction in multiple myeloma patients.

OBJECTIVE: Quantitative bone marrow (BM) MR sequences, as DWI and CSI, were used to evaluate BM water-fat composition. The aim of the study was to assess the potential usefulness of fat fraction (FF) and ADC, calculated by CSI or DWI, in diagnosing and classifying myeloma (MM) patients according to their different BM infiltration patterns. METHODS: The study group included 43 MM patients (19F; 24M; mean age 64 years), 15 asymptomatic, 15 symptomatic with diffuse BM infiltration and 13 symptomatic with focal lesions (FLs). The control group was made up of 15 healthy subjects (7F; 8M; mean age 64 years). MRI examinations consisted of sagittal T1w TSE on the spinal column, axial DWI (b 50-400-800 mm2/s) and coronal T2 Dixon, on the whole body. Mean ADC and FF were calculated placing 1 ROI on 6 vertebras and 2 ROIs on either the pelvis or FL. RESULTS: ANOVA with Bonferroni's correction showed a significant difference in ADC values among the different groups of MM patients (P < 0.05), while FF was only significantly different between patients with diffuse infiltration and patients with FL (P = 0.002). ADC allowed distinguishing MM patients from normal BM patients with diffuse BM infiltration (cutoff value: 0.491 × 10-3 mm2/s; sensitivity 73%, specificity 80%). FF helped better discriminate healthy controls from normal BM patients (cutoff = 0.33, sensitivity 73%, specificity 92%) and patients with diffuse BM infiltration from those with FL (cutoff = 0.16, sensitivity 82%, specificity 92%). CONCLUSION: ADC and FF are potentially useful parameter for the quantitative evaluation of BM infiltration in MM patients.

Whole-Body MRI with Diffusion-Weighted Imaging in Bone Metastases: A Narrative Review.

Whole body magnetic resonance imaging (MRI) with diffusion-weighted imaging (WB-MRI-DWI) is currently emerging as a diagnostic technique in the evaluation of bone metastases from breast, prostate, lung, thyroid, and melanoma tumors. The most relevant articles regarding the detection of solid tumor bone metastases with MRI have been reviewed and cited. The imaging methods currently used in the detection of bone metastases are bone scintigraphy, computed tomography (CT), and positron emission tomography (PET/CT) with 2-deoxy-2-[fluorine-18] fluoro-d-glucose (18F-FDG PET/CT). WB-MRI-DWI allows qualitative and quantitative evaluation of focal lesions through signal intensity evaluation on DWI images and the reconstruction of the apparent diffusion coefficient (ADC) map. In prostate and breast cancer, WB-MRI-DWI is useful in assessing the response of bone lesions to therapy and to detecting early non-responders, while in lung cancer the method shows a similar sensitivity to 18F-FDG PET/CT in the detection of bone metastases. In bone metastases of thyroid tumors and melanoma, the WB-MRI-DWI shows a higher sensitivity when compared to 18F-FDG PET/CT. With a standardization of the WB-MRI-DWI protocol, this method seems to play an important role in the diagnosis of bone solid tumor metastases.