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 , 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 mm /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 mm /s) than in malignant fractures or lesions (typically 0.7-1.3 × 10 mm /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.

Quantitative MRI and spectroscopy of bone marrow

“…In patients with normal bone marrow, yellow marrow content increases with age, with values between 50% and 60% for subjects older than 61 years, as measured using MRS . Due to the restriction of water diffusion induced by the tightly packed surrounding adipocytes in yellow marrow compared to red marrow, ADC values appear to be low in normal bone marrow with higher yellow marrow content, ranging from 0.2–0.6 × 10 ‐3 mm 2 /s, whereas the wide measured range may be explained by experimental differences and differences in fat saturation . In MM progression, water proton diffusivity increases with the increasing water content of the bone marrow due to plasma cell infiltration causing consequent yellow marrow content decrease, therefore ADC values increase, as does the hyperintense signal on DW imaging obtained using high b‐values .…”

“…). DW steady‐state free‐precession techniques have also shown good results in bone marrow applications . Their implementation is primarily challenged by the difficulties on relating the measured signal to the diffusion coefficient .…”

“…Using a DW single‐shot TSE sequence, ADC calculated with b = 100, 250, and 400 s/mm 2 provided the best diagnostic performance with a sensitivity of 85% and a specificity of 84.6%, using an ADC cutoff of 1.7 × 10 ‐3 mm 2 /s or less in order to differentiate a malignant vertebral fracture from a osteoporotic vertebral fracture . In a recent meta‐analysis of previously published studies, osteoporotic vertebral fractures demonstrate significantly greater ADC values (typically between 1.2 and 2.0 × 10 ‐3 mm 2 /s) than malignant vertebral fractures or lesions (typically between 0.7 and 1.3 × 10 ‐3 mm 2 /s) . DWI sequences without and with conventional fat saturation are in general highly influenced by bone marrow fat content, causing low signal in fat‐containing bone marrow which may lead to misinterpretation in the differentiation of malignant and benign processes within the bone marrow.…”

Diffusion MRI for Assessment of Bone Quality; A Review of Findings in Healthy Aging and Osteoporosis

“…In bone tissue, dMRI has been used to quantitatively assess pathophysiological changes of bone marrow beyond tissue relaxation parameters and fat content . dMRI is sensitive to random movement of water molecules within a space resulting from collision of molecules against each other, referred to as self‐diffusion , and characterized by a diffusion coefficient D self .…”

Kompresinių Stuburo Slankstelių Lūžių Klinikiniai Ir Radiologiniai Ypatumai Bei Jų Sąsajos Su Rizikos Veiksniais Moterims Pomenopauziniu Periodu

“…Įtariant kompresinį slankstelio lūžį, esant galimybei, būtų tikslingas ir senesnių radiologinių tyrimų vertinimas. Neaiškiais atvejais, esant klinikinei būtinybei, skiriami kiti radiologiniai tyrimai: magnetinio rezonanso tomografijos tyrimas (MRT) ir kaulų scintigrafijos tyrimas [31,32]. Kaulų čiulpų edemos požymiai MRT tyrime ar radionuklido kaupimas kauluose scintigrafijos metu rodo aktyvų ūmų procesą.…”