Advances in whole body MRI for musculoskeletal imaging: Diffusion-weighted imaging

Abstract

Recent advances in imaging technology have enabled the acquisition of anatomical and functional imaging from head to toe in a reasonably short scan time. Accordingly, whole body magnetic resonance imaging (WB-MRI) and diffusion-weighted imaging (WB-DWI) have gained recent attention for the management of musculoskeletal problems such as bone tumors and rheumatologic diseases. WB-MRI is especially useful in diagnosing systemic or widespread disease requiring whole body evaluation, such as bone metastases, multiple myeloma, lymphoma, neurofibromatosis, and spondyloarthropathies. Among WB-MRI sequences, the WB-DWI technique greatly increases the value of WB-MRI in the evaluation of disease extent and characterization as well as treatment monitoring. In support of the utilization of WB-MRI and WB-DWI in orthopedic clinics for various musculoskeletal diseases, we provide an overview of the technical aspects of WB-MRI and WB-DWI and their clinical applications in musculoskeletal tumors and rheumatic diseases.

Keywords: Bone; Diffusion-weighted imaging; Magnetic resonance imaging; Musculoskeletal; Whole body.

Figures

Fig. 1

Common sequences and planes for whole-body MRI. A 63-year-old male with multiple myeloma underwent a whole-body MRI scan for staging, including T2-and T1-weighted coronal images of the whole body (a, b); T2-and T1-weighted sagittal images of the spine (c, d); diffusion-weighted coronal and sagittal images of the torso (e, f); and contrast-enhanced axial images of the torso (g).

Fig. 2

Diagram of the associations between cellularity, diffusion of water molecules, and signal intensities of ADC and DWI. Low cellularity in normal cells results in high ADC values, while high cellularity in tumor cells restricts diffusion resulting in low ADC values.

Fig. 3

53-year-old patient with multiple myeloma treated with chemotherapy. (a) Before treatment, a large mass in the sternum and chest wall (thick arrows) showed contrast enhancement on CE (upper), high signal intensity on DWI (middle), and low ADC values on ADC map (lower). (b) Two months after initiation of chemotherapy, mass (thin arrows) shows decreased contrast enhancement (upper), decreased signal intensity on DWI (middle), and increased ADC value on ADC map (lower).

Fig. 4

A 39-year-old male with large thigh mass diagnosed as myxoid liposarcoma. Whole-body coronal T2-WI and T1-WI images (a, b) showing a large mass containing fat and myxoid components suggestive of myxoid liposarcoma. Additional thigh MRI provides detailed anatomical information of tumor (c, d).

Fig. 5

A 55-year-old male with hepatocellular carcinoma and back pain. T2-weighted coronal (a), sagittal (b), and axial (c) whole-body MRI show multifocal lesions with bone marrow signal alteration (thin arrows) at the costovertebral junctions and corners of vertebral bodies. T2-weighted axial image at sacroiliac joint level (d) shows bony ankyloses at bilateral sacroiliac joints (thick arrows) suggesting ankylosing spondylitis.