Associations Between Lumbar Vertebral Bone Marrow and Paraspinal Muscle Fat Compositions—An Investigation by Chemical Shift Encoding-Based Water-Fat MRI

Abstract

Purpose: Advanced magnetic resonance imaging (MRI) methods enable non-invasive quantification of body fat situated in different compartments. At the level of the lumbar spine, the paraspinal musculature is the compartment spatially and functionally closely related to the vertebral column, and both vertebral bone marrow fat (BMF) and paraspinal musculature fat contents have independently shown to be altered in various metabolic and degenerative diseases. However, despite their close relationships, potential correlations between fat compositions of these compartments remain largely unclear.Materials and Methods: Thirty-nine female subjects (38.5% premenopausal women, 29.9 ± 7.1 years; 61.5% postmenopausal women, 63.2 ± 6.3 years) underwent MRI at 3T of the lumbar spine using axially- and sagittally-prescribed gradient echo sequences for chemical shift encoding-based water-fat separation. The erector spinae muscles and vertebral bodies of L1–L5 were segmented to determine the proton density fat fraction (PDFF) of the paraspinal and vertebral bone marrow compartments. Correlations were calculated between the PDFF of the paraspinal muscle and bone marrow compartments.Results: The average PDFF of the paraspinal muscle and bone marrow compartments were significantly lower in premenopausal women when compared to postmenopausal women (11.6 ± 2.9% vs. 24.6 ± 7.1% & 28.8 ± 8.3% vs. 47.2 ± 8.5%; p < 0.001 for both comparisons). In premenopausal women, no significant correlation was found between the PDFF of the erector spinae muscles and the PDFF of the bone marrow of lumbar vertebral bodies (p = 0.907). In contrast, a significant correlation was shown in postmenopausal women (r = 0.457, p = 0.025). Significance was preserved after inclusion of age and body mass index (BMI) as control variables (r = 0.472, p = 0.027).Conclusion: This study revealed significant correlations between the PDFF of paraspinal and vertebral bone marrow compartments in postmenopausal women. The PDFF of the paraspinal and vertebral bone marrow compartments and their correlations might potentially serve as biomarkers; however, future studies including more subjects are required to evaluate distinct clinical value and reliability. Future studies should also follow up our findings in patients suffering from metabolic and degenerative diseases to clarify how these correlations change in the course of such diseases.

Bone Marrow and Muscle Fat Infiltration Are Correlated among Postmenopausal Women With Osteoporosis: The AMBERS Cohort Study

“…Bone and muscle measures were made in the appendicular anatomy, which could be restricted in generalization to more central sites such as the hip and spine. However, one previous study by Sollmann and colleagues observed similar correlations in fat fraction distributions between paraspinal muscles and vertebral bone marrow, albeit in a small cohort of 24 postmenopausal women ( r = 0.457, p = 0.025) …”

“…Only one study has been able to demonstrate this relationship so far but only among 24 postmenopausal women ( r = 0.457, p = 0.025) with minimal adjustment for confounders. Meanwhile, the authors found no association among the 15 premenopausal women ( p = 0.907) . No further studies have directly examined this relationship.…”

“…However, one previous study by Sollmann and colleagues observed similar correlations in fat fraction distributions between paraspinal muscles and vertebral bone marrow, albeit in a small cohort of 24 postmenopausal women (r = 0.457, p = 0.025). (1) Osteoporosis has been known as a disease of bone loss and in postmenopausal women largely related to the decline in estrogen levels. However, the less recognized effect of fat infiltration appears common in both bone (bone marrow) and muscle; in fact, the distribution of fat within these tissues are related as demonstrated in this study.…”

“…Meanwhile, the authors found no association among the 15 premenopausal women (p = 0.907). (1) No further studies have directly examined this relationship. Here, we present the body of evidence linking bone loss (osteoporosis) to an accumulation of fat within bone and muscle to support our rationale for studying this relationship.…”

Age- and BMI-related variations of fat distribution in sacral and lumbar bone marrow and their association with local muscle fat content

“…As shown in previous studies, bone marrow PDFF values show specific distribution patterns inter-and also intra-individually, depending on the topography within the lumbar spine, with increasing PDFF from cranial to caudal (L1 to L5) 3,9-11 . Furthermore, an age-dependent correlation between the structural composition of the local lumbar musculature and vertebral bone marrow fat has been described recently 12 . A systematic analysis of the functional impact associated with these pathophysiological processes using isometric strength measurements showed that an increased fatty infiltration of the paraspinal muscles significantly correlated with reduced muscle strength 13,14 .…”