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

Abstract

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.

Bone metastases from differentiated thyroid carcinoma: current knowledge and open issues

“…Furthermore, in case of vertebral metastases, MRI is essential for the assessment of epidural, nerve, and spinal cord involvement, playing a pivotal role in the pre-surgical workup [ 21 , 22 ]. Whole-body (WB) MRI with diffusion-weighted imaging (MRI-DWI) is a promising imaging technique in the evaluation of BM from different solid tumours, including DTC [ 23 ]. The added value of DWI is the addiction of functional information to morphological sequences: being able to detect differences in cellularity of malignant bone marrow disorders with respect to the normal bone marrow, it might help in differentiating between malignant and benign lesions.…”

Bone Metastases in Neuroendocrine Neoplasms: From Pathogenesis to Clinical Management

“…Bone lesions deriving from NENs appeared predominantly osteoblastic (up to 83% of cases), whereas osteolytic or mixed patterns were less frequent [11,41]. MRI was shown to have a sensitivity of nearly 100% for the detection of bone marrow metastases [13,68], and particularly, whole-body MRI associated with body diffusion-weighted imaging (DWI) better distinguished benign from malignant bone lesions [69]. Recently, no significant differences between CT and MRI for the detection of BMs have been demonstrated [18].…”

An international expert opinion statement on the utility of PET/MR for imaging of skeletal metastases

“…Detection of metastases by CT requires destruction of cortical or trabecular bone, adjacent sclerotic changes, or identification of soft tissue attenuation within the normal fat-attenuation marrow. In contrast, skeletal metastases on MR can be characterized by signal abnormality of the bone marrow on T1, STIR, and diffusion-weighted sequences [36][37][38][39][40]. Numerous studies have shown that MR is more sensitive than CT alone in the detection of focal marrow replacing lesions and that the higher soft tissue contrast provided by MR allows for better delineation of extra-osseous tumor spread and spinal cord compression (Fig.…”