Ethnic and sex differences in bone marrow adipose tissue and bone mineral density relationship

The Role of Sex Differences in Bone Health and Healing

Fracture healing is a long-term and complex process influenced by a huge variety of factors. Among these, there is a sex/gender disparity. Based on significant differences observed in the outcome of bone healing in males and females, in the present review, we report the main findings, hypotheses and pitfalls that could lead to these differences. In particular, the role of sex hormones and inflammation has been reported to have a role in the observed less efficient bone healing in females in comparison with that observed in males. In addition, estrogen-induced cellular processes such as autophagic cell cycle impairment and molecular signals suppressing cell cycle progression seem also to play a role in female fracture healing delay. In conclusion, it seems conceivable that a complex framework of events could contribute to the female bias in bone healing, and we suggest that a reappraisal of the compelling factors could contribute to the mitigation of sex/gender disparity and improve bone healing outcomes.

Biomechanical MRI detects reduced bone strength in subjects with vertebral fractures

Vertebral fracture is one of the most serious consequences of osteoporosis. Estimation of vertebral strength from magnetic resonance imaging (MRI) scans may provide a new approach for the prediction of vertebral fractures. To that end, we sought to establish a biomechanical MRI (BMRI) method to compute vertebral strength and test its ability to distinguish fracture from non-fracture subjects. This case-control study included 30 subjects without vertebral fractures and 15 subjects with vertebral fractures. All subjects underwent MRI with a mDIXON-Quant sequence and quantitative computed tomography (QCT), from which proton fat fraction-based bone marrow adipose tissue (BMAT) content and volumetric bone mineral density (vBMD) were measured, respectively. Nonlinear finite element analysis was applied to MRI and QCT scans of L2 vertebrae to compute vertebral strength (BMRI- and BCT-strength). The differences in BMAT content, vBMD, BMRI-strength and BCT-strength between the two groups were examined by t-tests. Receiver operating characteristic (ROC) analysis was performed to assess the ability of each measured parameter to distinguish fracture from non-fracture subjects. Results showed that the fracture group had 23 % lower BMRI-strength (P < .001) and 19 % higher BMAT content (P < .001) than the non-fracture group, whereas no significant difference in vBMD was detected between the two groups. A poor correlation was found between vBMD and BMRI-strength (R² = 0.33). Compared to vBMD and BMAT content, BMRI- and BCT-strength had the larger area under the curve (0.82 and 0.84, respectively) and provided better sensitivity and specificity in separating fracture from non-fracture subjects. In conclusion, BMRI is capable of detecting reduced bone strength in patients with vertebral fracture, and may serve as a new approach for risk assessment of vertebral fracture.

Exercise may impact on lumbar vertebrae marrow adipose tissue: Randomised controlled trial

BACKGROUND

Animal and human cross-sectional data suggest that bone marrow adipose tissue (MAT) may respond to mechanical loads and exercise. We conducted the first randomised controlled trial of exercise on MAT modulations in humans.

METHODS

Forty patients with chronic non-specific low back pain (NSCLBP) were enrolled in a six-month single-blinded randomised controlled trial (ACTRN12615001270505). Twenty patients loaded their spines via progressive upright aerobic and resistance exercises targeting major muscle groups (Exercise). Twenty patients performed non-weightbearing motor control training and manual therapy (Control). Testing occurred at baseline, 3-months (3mo) and 6-months (6mo). Lumbar vertebral fat fraction (VFF) was measured using magnetic resonance imaging axial mDixon sequences.

RESULTS

When compared to baseline (percent change), lumbar vertebral fat fraction (VFF; measured using magnetic resonance imaging axial mDixon sequences) was lower in Exercise at 3mo at L2 (-3.7[6.8]%, p = 0.033) and L4 (-2.6[4.1]%, p = 0.015), but not in Control. There were no between-group effects. The effects of Exercise on VFF were sex-specific, with VFF lower in men at L2, L3, L4 at 3mo and at L1, L2, L3 and L4 at 6mo (p all ≤ 0.05), but not in women. Leg and trunk lean mass were increased at 3mo in Exercise. Changes in VFF correlated significantly with changes in total fat (ρ = 0.40) and lean (ρ = -0.41) masses, but not with lumbar BMD (ρ = -0.10) or visceral adipose tissue volume (ρ = 0.23).

CONCLUSIONS

This trial provided first prospective evidence in humans that a moderate exercise intervention may modulate lumbar VFF as a surrogate measure of MAT at 3mo, yet not 6mo. The effect of exercise on MAT may be more prominent in males than females.

A-769662 stimulates the differentiation of bone marrow-derived mesenchymal stem cells into osteoblasts via AMP-activated protein kinase-dependent mechanism

AMP-activated protein kinase (AMPK) signaling shows an important role in energy metabolism and has recently been involved in osteogenic and adipogenic differentiation. In this study we aimed to investigate the role of AMPK activator, A-769662, in regulating the differentiation of mesenchymal stem cells derived from bone marrow (BMSCs) into osteoblastic and adipocytic cell lineage. The effect of A-769662 on osteogenesis was assessed by quantitative alkaline phosphatase (ALP) activity, matrix mineralization stained with Alizarin red, and gene expression analysis by quantitative polymerase chain reaction (qPCR). Adipogenesis was determined by Oil Red O staining for fat droplets and qPCR analysis of adipogenic markers. A-769662 activated the phosphorylation of AMPKα1 during the osteogenesis of mBMSCs as revealed by western blot analysis. A-769662 promoted the early stage of the commitment of mouse (m) BMSCs differentiation into osteoblasts, while inhibiting their differentiation into adipocytes in a dose-dependent manner. The effects of A-769662 on stimulating osteogenesis and inhibiting adipogenesis of mBMSCs were significantly eliminated in the presence of either AMPKα1 siRNA or Compound C, an inhibitor of AMPK pathway. In conclusion, we identified A-769662 as a new compound that promotes the commitment of BMSCs into osteoblasts versus adipocytes via AMPK-dependent mechanism. Thus our data show A-769662 as a potential osteo-anabolic drug for treatment of osteoporosis.

The accurate relationship between spine bone density and bone marrow in humans

CONTEXT

The accuracy of QCT measurements of lumbar spine trabecular volumetric bone mineral density (vBMD) is decreased due to differences in the amount of bone marrow adipose tissue (BMAT).

OBJECTIVE

To correct vBMD measurements for differences in marrow composition and investigate the true relationship between vBMD and BMAT.

DESIGN

Cross-sectional study.

SETTING

University teaching hospital.

PARTICIPANTS

Healthy Chinese subjects (233 women, 167 men) aged between 21 and 82 years.

MAIN OUTCOME MEASURES

vBMD and BMAT were measured using QCT (120 kV) and chemical shift-encoded MRI of the L2-L4 vertebrae. vBMD measurements were standardized to the European Spine Phantom (ESP) and corrected for differences in BMAT. Linear regression was used to analyze BMAT, ESP adjusted vBMD (vBMD_ESPcorr) and BMAT corrected vBMD (vBMD_BMATcorr) against age and corrected vBMD against BMAT.

RESULTS

BMAT in the L2-L4 vertebral bodies increased with age in both sexes, with a faster rate of change in women compared with men (0.54%/year vs. 0.27%/year, P < 0.0001). After vBMD measurements were corrected for BMAT there were statistically significant changes in the slope of the regression line with age in both sexes (women: -3.00 ± 0.13 vs. -2.57 ± 0.11 mg/cm³/year, P < 0.0001; men: -1.92 ± 0.15 vs. -1.70 ± 0.14 mg/cm³/year, P < 0.0001). When vBMD_BMATcorr was plotted against BMAT, vBMD decreased linearly with increasing BMAT in both sexes (women: -3.30 ± 0.18 mg/cm³/%; men: -2.69 ± 0.25 mg/cm³/%, P = 0.048).

CONCLUSION

Our approach reveals the true relationship between vBMD and BMAT and provides a new tool for studying the interaction between bone and marrow adipose tissue.

Bone Marrow Fat Physiology in Relation to Skeletal Metabolism and Cardiometabolic Disease Risk in Children With Cerebral Palsy

Individuals with cerebral palsy exhibit neuromuscular complications and low physical activity levels. Adults with cerebral palsy exhibit a high prevalence of chronic diseases, which is associated with musculoskeletal deficits. Children with cerebral palsy have poor musculoskeletal accretion accompanied by excess bone marrow fat, which may lead to weaker bones. Mechanistic studies to determine the role of bone marrow fat on skeletal growth and maintenance and how it relates to systemic energy metabolism among individuals with cerebral palsy are lacking. In this review, we highlight the skeletal status in children with cerebral palsy and analyze the existing literature on the interactions among bone marrow fat, skeletal health, and cardiometabolic disease risk in the general population. Clinically vital questions are proposed, including the following: (1) Is the bone marrow fat in children with cerebral palsy metabolically distinct from typically developing children in terms of its lipid and inflammatory composition? (2) Does the bone marrow fat suppress skeletal acquisition? (3) Or, does it accelerate chronic disease development in children with cerebral palsy? (4) If so, what are the mechanisms? In conclusion, although inadequate mechanical loading may initiate poor skeletal development, subsequent expansion of bone marrow fat may further impede skeletal acquisition and increase cardiometabolic disease risk in those with cerebral palsy.

Fat-bone interaction within the bone marrow milieu: Impact on hematopoiesis and systemic energy metabolism

The relationship between fat, bone and systemic metabolism is a growing area of scientific interest. Marrow adipose tissue is a well-recognized component of the bone marrow milieu and is metabolically distinct from current established subtypes of adipose tissue. Despite recent advances, the functional significance of marrow adipose tissue is still not clearly delineated. Bone and fat cells share a common mesenchymal stem cell (MSC) within the bone marrow, and hormones and transcription factors such as growth hormone, leptin, and peroxisomal proliferator-activated receptor γ influence MSC differentiation into osteoblasts or adipocytes. MSC osteogenic potential is more vulnerable than adipogenic potential to radiation and chemotherapy, and this confers a risk for an abnormal fat-bone axis in survivors following cancer therapy and bone marrow transplantation. This review provides a summary of data from animal and human studies describing the relationship between marrow adipose tissue and hematopoiesis, bone mineral density, bone strength, and metabolic function. The significance of marrow adiposity in other metabolic disorders such as osteoporosis, diabetes mellitus, and estrogen and growth hormone deficiency are also discussed. We conclude that marrow adipose tissue is an active endocrine organ with important metabolic functions contributing to bone energy maintenance, osteogenesis, bone remodeling, and hematopoiesis. Future studies on the metabolic role of marrow adipose tissue may provide the critical insight necessary for selecting targeted therapeutic interventions to improve altered hematopoiesis and augment skeletal remodeling in cancer survivors.

Increased bone mass in a mouse model with low fat mass

Mice with impaired acute inflammatory responses within adipose tissue display reduced diet-induced fat mass gain associated with glucose intolerance and systemic inflammation. Therefore, acute adipose tissue inflammation is needed for a healthy expansion of adipose tissue. Because inflammatory disorders are associated with bone loss, we hypothesized that impaired acute adipose tissue inflammation leading to increased systemic inflammation results in a lower bone mass. To test this hypothesis, we used mice overexpressing an adenoviral protein complex, the receptor internalization and degradation (RID) complex that inhibits proinflammatory signaling, under the control of the aP2 promotor (RID tg mice), resulting in suppressed inflammatory signaling in adipocytes. As expected, RID tg mice had lower high-fat diet-induced weight and fat mass gain and higher systemic inflammation than littermate wild-type control mice. Contrary to our hypothesis, RID tg mice had increased bone mass in long bones and vertebrae, affecting trabecular and cortical parameters, as well as improved humeral biomechanical properties. We did not find any differences in bone formation or resorption parameters as determined by histology or enzyme immunoassay. However, bone marrow adiposity, often negatively associated with bone mass, was decreased in male RID tg mice as determined by histological analysis of tibia. In conclusion, mice with reduced fat mass due to impaired adipose tissue inflammation have increased bone mass.

Role of Fat and Bone Biomarkers in the Relationship Between Ethnicity and Bone Mineral Density in Older Men

Osteoporosis is an important health issue for older adults, and has been relatively understudied in older men. This study aimed to examine ethnic differences in bone mineral density (BMD), and elucidate the role of bone turnover markers (BTMs), fat and fat biomarkers on these ethnic differences. BMD at the lumbar spine and femoral neck, marrow fat at femoral neck, visceral adipose tissue (VAT) and subcutaneous adipose tissue, bone and fat biomarkers were evaluated in 120 healthy men aged ≥ 60 years. Indians had higher BMD values compared to Chinese at the lumbar spine (β = 20.336, SE = 4.749, p < 0.001) and the femoral neck (e ^β  = 1.105, SE = 0.032, p < 0.001), after adjusting for BTMs, fat composition and lifestyle choices. Marrow fat, VAT and adiponectin were independent predictors of BMD. However, these factors did not explain the lower BMD observed in older Chinese men. Our findings suggest that older Chinese men are at significant risk of osteoporotic fractures due to lower BMD. Fat appears to be a key factor associated with lower BMD, and warrants further longitudinal studies to elucidate the complex interactions between adipose tissue and bone strength.

Mesenchymal progenitors in osteopenias of diverse pathologies: differential characteristics in the common shift from osteoblastogenesis to adipogenesis

Osteoporosis is caused by pathologic factors such as aging, hormone deficiency or excess, inflammation, and systemic diseases like diabetes. Bone marrow stromal cells (BMSCs), the mesenchymal progenitors for both osteoblasts and adipocytes, are modulated by niche signals. In differential pathologic states, the pathological characteristics of BMSCs to osteoporoses and functional differences are unknown. Here, we detected that trabecular bone loss co-existed with increased marrow adiposity in 6 osteoporotic models, respectively induced by natural aging, accelerated senescence (SAMP6), ovariectomy (OVX), type 1 diabetes (T1D), excessive glucocorticoids (GIOP) and orchidectomy (ORX). Of the ex vivo characteristics of BMSCs, the colony-forming efficiency and the proliferation rate in aging, SAMP6, OVX, GIOP and ORX models decreased. The apoptosis and cellular senescence increased except in T1D, with up-regulation of p53 and p16 expression. The osteogenesis declined except in GIOP, with corresponding down-regulation of Runt-related transcription factor 2 (RUNX2) expression. The adipogenesis increased in 6 osteoporotic models, with corresponding up-regulation of Peroxisome proliferator activated receptor gamma (PPARγ) expression. These findings revealed differential characteristics of BMSCs in a common shift from osteoblastogenesis to adipogenesis among different osteoporoses and between sexes, and provide theoretical basis for the functional modulation of resident BMSCs in the regenerative therapy for osteoporosis.

Marrow Adipose Tissue: Trimming the Fat

Marrow adipose tissue (MAT) is a unique fat depot, located in the skeleton, that has the potential to contribute to both local and systemic metabolic processes. In this review we highlight several recent conceptual developments pertaining to the origin and function of MAT adipocytes; consider the relationship of MAT to beige, brown, and white adipose depots; explore MAT expansion and turnover in humans and rodents; and discuss future directions for MAT research in the context of endocrine function and metabolic disease. MAT has the potential to exert both local and systemic effects on metabolic homeostasis, skeletal remodeling, hematopoiesis, and the development of bone metastases. The diversity of these functions highlights the breadth of the potential impact of MAT on health and disease.

Marrow adiposity assessed on transiliac crest biopsy samples correlates with noninvasive measurement of marrow adiposity by proton magnetic resonance spectroscopy ((1)H-MRS) at the spine but not the femur

Measurement of marrow fat (MF) is important to the study of bone fragility. We measured MF on iliac biopsies and by spine/hip magnetic resonance spectroscopy in the same subjects. Noninvasively assessed spine MF and histomorphometrically assessed MF correlated well. MF quantity and relationships with bone volume differed by measurement site.

INTRODUCTION

Excess marrow fat has been implicated in the pathogenesis of osteoporosis in several populations. In the bone marrow, adipocytes and osteoblasts share a common precursor and are reciprocally regulated. In addition, adipocytes may secrete toxic fatty acids and adipokines that adversely affect osteoblasts. Measurement of marrow fat is important to the study of mechanisms of bone fragility. Marrow fat can be quantified on bone biopsy samples by histomorphometry and noninvasively by proton magnetic resonance spectroscopy ((1)H-MRS). In this study, we evaluate relationships between marrow fat assessed using both methods in the same subjects for the first time.

METHODS

Sixteen premenopausal women, nine with idiopathic osteoporosis and seven normal controls, had marrow fat measured at the iliac crest by bone biopsy and at the lumbar spine (L3) and proximal femur by (1)H-MRS.

RESULTS

At L3, fat fraction by (1)H-MRS correlated directly and significantly with marrow fat variables on iliac crest biopsies (r = 0.5-0.8). In contrast, there were no significant correlations between fat fraction at the femur and marrow fat on biopsies. Marrow fat quantity (%) was greater at the femur than at L3 and the iliac crest and correlated inversely with total hip and femoral neck BMD by DXA.

CONCLUSIONS

In summary, measurement of marrow fat in transiliac crest biopsies correlates with marrow fat at the spine but not the proximal femur by (1)H-MRS. There were site-specific differences in marrow fat quantity and in the relationships between marrow fat and bone volume.

Magnetic resonance imaging-measured bone marrow adipose tissue area is inversely related to cortical bone area in children and adolescents aged 5-18 years

Previous studies have shown an inverse correlation between bone marrow adipose tissue and bone mineral density in cancellous bone; however, such relationships in cortical bone are less studied, especially in children. A total of 185 healthy children and adolescents (76 females and 109 males, aged 5-18 years) were included in this study. Right femoral bone marrow adipose tissue area (BMA), right femoral cortical bone area (CBA), subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle were accessed by whole-body magnetic resonance imaging. In regression analysis with CBA as the dependent variable and BMA as the independent variable, BMA negatively contributed to CBA after adjusting for weight and total body fat or subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle (β = -0.201 to -0.272, p < 0.001). These results suggest an inverse relationship between BMA and CBA in children and adolescents after adjustment of body weight or body composition. The data support the hypothesis that a competitive relationship exists between bone and marrow fat in cortical bone and is consistent with a similar finding in cancellous bone in previous studies. Future research is needed to clarify the role of marrow fat in childhood fractures that are related to cortical bone quality.

Marrow fat and bone: review of clinical findings

With growing interest in the connection between fat and bone, there has been increased investigation of the relationship with marrow fat in particular. Clinical research has been facilitated by the development of non-invasive methods to measure bone marrow fat content and composition. Studies in different populations using different measurement techniques have established that higher marrow fat is associated with lower bone density and prevalent vertebral fracture. The degree of unsaturation in marrow fat may also affect bone health. Although other fat depots tend to be strongly correlated, marrow fat has a distinct pattern, suggesting separate mechanisms of control. Longitudinal studies are limited, but are crucial to understand the direct and indirect roles of marrow fat as an influence on skeletal health. With greater appreciation of the links between bone and energy metabolism, there has been growing interest in understanding the relationship between marrow fat and bone. It is well established that levels of marrow fat are higher in older adults with osteoporosis, defined by either low bone density or vertebral fracture. However, the reasons for and implications of this association are not clear. This review focuses on clinical studies of marrow fat and its relationship to bone.

What's the matter with MAT? Marrow adipose tissue, metabolism, and skeletal health

Marrow adipose tissue (MAT) is functionally distinct from both white and brown adipose tissue and can contribute to systemic and skeletal metabolism. MAT formation is a spatially and temporally defined developmental event, suggesting that MAT is an organ that serves important functions and, like other organs, can undergo pathologic change. The well-documented inverse relationship between MAT and bone mineral density has been interpreted to mean that MAT removal is a possible therapeutic target for osteoporosis. However, the bone and metabolic phenotypes of patients with lipodystrophy argues that retention of MAT may actually be beneficial in some circumstances. Furthermore, MAT may exist in two forms, regulated and constitutive, with divergent responses to hematopoietic and nutritional demands. In this review, we discuss the role of MAT in lipodystrophy, bone loss, and metabolism, and highlight our current understanding of this unique adipose tissue depot.

Comparison of the relationship between bone marrow adipose tissue and volumetric bone mineral density in children and adults

Several large-scale studies have reported the presence of an inverse relationship between bone mineral density (BMD) and bone marrow adipose tissue (BMAT) in adults. We aim to determine if there is an inverse relationship between pelvic volumetric BMD (vBMD) and pelvic BMAT in children and to compare this relationship in children and adults. Pelvic BMAT and bone volume (BV) was evaluated in 181 healthy children (5-17yr) and 495 healthy adults (≥18yr) with whole-body magnetic resonance imaging (MRI). Pelvic vBMD was calculated using whole-body dual-energy X-ray absorptiometry to measure pelvic bone mineral content and MRI-measured BV. An inverse correlation was found between pelvic BMAT and pelvic vBMD in both children (r=-0.374, p<0.001) and adults (r=-0.650, p<0.001). In regression analysis with pelvic vBMD as the dependent variable and BMAT as the independent variable, being a child or adult neither significantly contribute to the pelvic BMD (p=0.995) nor did its interaction with pelvic BMAT (p=0.415). The inverse relationship observed between pelvic vBMD and pelvic BMAT in children extends previous findings that found the inverse relationship to exist in adults and provides further support for a reciprocal relationship between adipocytes and osteoblasts.

Influence of bone marrow composition on measurements of trabecular microstructure using decay due to diffusion in the internal field MRI: simulations and clinical studies

PURPOSE

Decay due to diffusion in the internal field (DDIF) MRI allows for measurements of microstructures of porous materials at low spatial resolution and thus has potential for trabecular bone quality measurements. In trabecular bone, solid bone changes (osteoporosis) as well as changes in bone marrow composition occur. The influence of such changes on DDIF MRI was studied by simulations and in vivo measurements.

METHODS

Monte Carlo simulations of DDIF in various trabecular bone models were conducted. Changes in solid bone and marrow composition were simulated with numerical bone erosion and marrow susceptibility variations. Additionally, in vivo measurements were performed in the lumbar spine of healthy volunteers aged 23-62 years.

RESULTS

Simulations and in vivo results showed that 1) DDIF decay times decrease with increasing marrow fat and 2) the marrow fat percentage needs to be incorporated in the DDIF analysis to discriminate between healthy and osteoporotic solid bone structures.

CONCLUSIONS

Bone marrow composition plays an important role in DDIF MRI: incorporation of marrow fat percentage into DDIF MRI allowed for differentiation of young and old age groups (in vivo experiments). DDIF MRI may develop into a means of assessing osteoporosis and disorders that affect marrow composition.

Noncontrast cardiac computed tomography image-based vertebral bone mineral density: the Multi-Ethnic Study of Atherosclerosis (MESA)

RATIONALE AND OBJECTIVES

Cardiac computer tomography (CT) image-based vertebral bone mineral density (BMD) assessment and the influence of cardiovascular disease risk factors on BMD have not been systematically evaluated, especially in a community-based, multiethnic population.

METHODS

A cross-sectional study design is used to determine if cardiac CT image is a reliable source to assess vertebral BMD, and a total of 2028 CT images were obtained from the Multi-Ethnic Study of Atherosclerosis, a large, diverse US cohort of adults 45 to 84 years of age.

RESULTS

Cardiac CT image allows the rapid assessment of vertebral BMD and related fractures. The mean BMD was significantly higher in men compared with women for thoracic vertebrae (143.2 ± 41.2 vs 138.7 ± 42.7 mg/cm³, respectively, P = .014), as well as for lumbar vertebrae (125.0 ± 37.9 vs 117.2 ± 39.4 mg/cm³, respectively, P < .0001). Thoracic and lumbar BMDs are closely correlated (correlation coefficient 0.87, P < .001), independent of age and other confounders including sex and race. African American men had the highest thoracic BMD among all race/ethnicity and sex subgroups. Prevalence of fractures in total vertebrae is 4.2%. Lumbar had approximately 2 times higher prevalence of fracture than thoracic, and the prevalence of vertebral fractures is 1.5% and 3.1% for thoracic and lumbar vertebrae, respectively.

CONCLUSIONS

Using cardiac CT images to garner and assess vertebral BMD is a feasible and reliable method. Cardiac CT has the additional advantages of evaluate vertebral bone health while assessing cardiovascular disease risk with no extra cost or radiation exposure.

Comparison among T1-weighted magnetic resonance imaging, modified dixon method, and magnetic resonance spectroscopy in measuring bone marrow fat

INTRODUCTION

An increasing number of studies are utilizing different magnetic resonance (MR) methods to quantify bone marrow fat due to its potential role in osteoporosis. Our aim is to compare the measurements of bone marrow fat among T1-weighted magnetic resonance imaging (MRI), modified Dixon method (also called fat fraction MRI (FFMRI)), and magnetic resonance spectroscopy (MRS).

METHODS

Contiguous MRI scans were acquired in 27 Caucasian postmenopausal women with a modified Dixon method (i.e., FFMRI). Bone marrow adipose tissue (BMAT) of T1-weighted MRI and bone marrow fat fraction of the L3 vertebra and femoral necks were quantified using SliceOmatic and Matlab. MRS was also acquired at the L3 vertebra.

RESULTS

Correlation among the three MR methods measured bone marrow fat fraction and BMAT ranges from 0.78 to 0.88 (P < 0.001) in the L3 vertebra. Correlation between BMAT measured by T1-weighted MRI and bone marrow fat fraction measured by modified FFMRI is 0.86 (P < 0.001) in femoral necks.

CONCLUSION

There are good correlations among T1-weighted MRI, FFMRI, and MRS for bone marrow fat quantification. The inhomogeneous distribution of bone marrow fat, the threshold segmentation of the T1-weighted MRI, and the ambiguity of the FFMRI may partially explain the difference among the three methods.