title: Diffusion imaging of the vertebral bone marrow.
abstract: Diffusion-weighted MRI (DWI) of the vertebral bone marrow is a clinically important tool for the characterization of bone-marrow pathologies and, in particular, for the differentiation of benign (osteoporotic) and malignant vertebral compression fractures. DWI of the vertebral bone marrow is, however, complicated by some unique MR and tissue properties of vertebral bone marrow. Due to both the spongy microstructure of the trabecular bone and the proximity of the lungs, soft tissue, or large vessels, substantial magnetic susceptibility variations occur, which severely reduce the magnetic field homogeneity as well as the transverse relaxation time T*2, and thus complicate MRI in particular with echoplanar imaging (EPI) techniques. Therefore, alternative diffusion-weighting pulse sequence types such as single-shot fast-spin-echo sequences or segmented EPI techniques became important alternatives for quantitative DWI of the vertebral bone marrow. This review first describes pulse sequence types that are particularly important for DWI of the vertebral bone marrow. Then, data from 24 studies that made diffusion measurements of normal vertebral bone marrow are reviewed; summarizing all results, the apparent diffusion coefficient (ADC) of normal vertebral bone marrow is typically found to be between 0.2 and 0.6 × 10-3mm2/s. Finally, DWI of vertebral compression fractures is discussed. Numerous studies demonstrate significantly greater ADCs in osteoporotic fractures (typically between 1.2 and 2.0 × 10-3mm2/s) than in malignant fractures or lesions (typically 0.7-1.3 × 10-3mm2/s). Alternatively, several studies used the (qualitative) image contrast of diffusion-weighted acquisitions for differentiation of lesion etiology: a very good lesion differentiation can be achieved, particularly with diffusion-weighted steady-state free precession sequences, which depict malignant lesions as hyperintense relative to normal-appearing vertebral bone marrow, in contrast to hypointense or isointense osteoporotic lesions. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Ludwig Maximilian University Hospital Munich, Germany.
authors.forename: Olaf
authors.identifier: http://orcid.org/0000-0001-6182-5039
authors.initials: O
authors.lastname: Dietrich
authors.affiliation: Institute for Clinical Radiology, Ludwig Maximilian University Hospital Munich, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Geith
authors.affiliation: Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Ludwig Maximilian University Hospital Munich, Germany.|Institute for Clinical Radiology, Ludwig Maximilian University Hospital Munich, Germany.
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.affiliation: Institute for Clinical Radiology, Ludwig Maximilian University Hospital Munich, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Baur-Melnyk
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000473:pathology; D001855:Bone Marrow Diseases / Q000000981:diagnostic imaging*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D019317:Evidence-Based Medicine; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000000981:diagnostic imaging*; D016103:Spinal Fractures / Q000000981:diagnostic imaging*; D013131:Spine / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: diffusion-weighted MRI; spinal column; vertebral bodies; vertebral bone marrow; vertebral compression fractures