Quantification of bone marrow water and lipid composition in anterior cruciate ligament-injured and osteoarthritic knees using three-dimensional magnetic resonance spectroscopic imaging

Fatty Acids Composition of the Sacroiliac Joint in Axial Spondyloarthritis: Analysis Using 3.0 T Chemical Shift-Encoded MRI

BACKGROUND

Axial spondyloarthritis (axSpA) is a group of inflammatory diseases that may lead to ankylosis of the sacroiliac joint and spine. Fat lesion in the sacroiliac joint is an important feature in diagnosis and disease progression of axSpA. However, whether there is alteration of fatty acids (FAs) composition has not been investigated using MRI.

PURPOSE

To investigate bone marrow FA composition of the sacroiliac joint in patients with axSpA compared to controls.

STUDY TYPE

Prospective.

SUBJECTS

Eighty five participants (mean age, 32.3 ± 6.1 years): 48 axSpA (25 male, 23 female) and 37 non-SpA controls (18 male, 19 female).

FIELD STRENGTH/SEQUENCE

3.0 T/Two multiple gradient-echo chemical shift-encoded (CSE) MRI which differed only in echo times (TEs) were scanned consecutively.

ASSESSMENT

Axial multi-echo CSE MRI was performed in the sacroiliac joints in vivo. Regions of interest (ROIs) were manually placed on subchondral bone with and without fat lesion in axSpA patients, and on subchondral bone without fat lesion in controls. FA composition was computed within the ROIs using a nonlinear least square method from literature.

STATISTICAL TESTS

Intergroup comparisons were performed using t tests.

RESULTS

In axSpA, male patients had significantly higher monounsaturated FA compared to controls in areas with fat lesion in the sacrum (+12%) and in the ilium (+9%), and in areas without fat lesion in the sacrum (+10%). Significantly lower polyunsaturated FAs were found in areas with fat lesion in the sacrum (-10%) and ilium (-11%), and lower saturated FAs were found in areas without fat lesion in the sacrum (-6%). In female, patients with axSpA had significantly higher saturated FAs in areas with fat lesion in the ilium (+7%) in comparison to controls.

DATA CONCLUSION

FA composition of the sacroiliac joint alters in patients with axSpA, and it can be detected using CSE MRI based analysis.

Imaging‐based assessment of fatty acid composition in human bone marrow adipose tissue at 7 T: Method comparison and in vivo feasibility

PURPOSE

To demonstrate the feasibility and accuracy of chemical shift-encoded imaging of the fatty acid composition (FAC) of human bone marrow adipose tissue at 7 T, and to determine suitable image-acquisition parameters using simulations.

METHODS

The noise performance of FAC estimation was investigated using simulations with a range of inter-echo time, and accuracy was assessed using a phantom experiment. Furthermore, one knee of 8 knee-healthy subjects (ages 35-54 years) was imaged, and the fractions of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) were mapped. Values were compared between reconstruction methods, and between anatomical regions.

RESULTS

Based on simulations, ΔTE = 0.6 ms was chosen. The phantom experiment demonstrated high accuracy of especially SFA using a constrained reconstruction model (slope = 1.1, average bias = -0.2%). The lowest accuracy was seen for PUFA using a free model (slope = 2.0, average bias = 9.0%). For in vivo images, the constrained model resulted in lower intersubject variation compared with the free model (e.g., in the femoral shaft, the SFA percent-point range was within 1.0% [vs. 3.0%]). Furthermore, significant regional FAC differences were detected. For example, using the constrained approach, the femoral SFA in the medial condyle was lower compared with the shaft (median [range]: 27.9% [27.1%, 28.4%] vs. 32.5% [31.8%, 32.8%]).

CONCLUSION

Bone marrow adipose tissue FAC quantification using chemical-shift encoding is feasible at 7 T. Both the noise performance and accuracy of the technique are superior using a constrained signal model.

Quantitative spatial mapping of tissue water and lipid content using spatial frequency domain imaging in the 900- to 1000-nm wavelength region

Significance

Water and lipid are key participants of many biological processes, but there are few label-free, non-contact optical methods that can spatially map these components in-vivo. Shortwave infrared meso-patterned imaging (SWIR-MPI) is an emerging technique that successfully addresses this need. However, it requires a dedicated SWIR camera to probe the 900- to 1300-nm wavelength region, which hinders practical translation of the technology.

Aim

Compared with SWIR-MPI, we aim to develop a new technique that can dramatically reduce the cost in detector while maintaining high accuracy for the quantification of tissue water and lipid content.

Approach

By utilizing water and lipid absorption features in the 900- to 1000-nm wavelength region as well as optimal wavelength and spatial frequency combinations, we develop a new imaging technique based on spatial frequency domain imaging to quantitatively map tissue water and lipid content using a regular silicon-based camera.

Results

The proposed method is validated with a phantom study, which shows average error of 0.9 ± 1.2 % for water content estimation, and -0.4 ± 0.7 % for lipid content estimation, respectively. The proposed method is also demonstrated for ex vivo porcine tissue lipid mapping as well as in-vivo longitudinal water content monitoring.

Conclusions

The proposed technique enables spatial mapping of tissue water and lipid content with the cost in detector reduced by two orders of magnitude compared with SWIR-MPI while maintaining high accuracy. The experimental results highlight the potential of this technique for substantial impact in both scientific and industrial applications.

Low Unsaturated Fatty Acids Level in the Vertebral Bone Marrow of Postmenopausal Osteoporosis: A Pilot 2D iDQC‐MRS on 3.0 T Study

BACKGROUND

Unsaturated fatty acids (UFAs) of bone marrow play a critical role in osteoporosis. However, it is difficult to resolve the UFA, especially in the presence of trabecular bone, using conventional magnetic resonance spectroscopy (MRS) methods.

PURPOSE

To preliminarily compare the bone marrow fatty acids (FAs) composition in the presence of trabecular bone of postmenopausal osteoporosis (PMOP) and healthy controls (HC).

STUDY TYPE

Prospective.

SUBJECTS

Total thirty-six postmenopausal women were recruited with CT-confirmed PMOP (n = 19) and HC (n = 17).

FIELD STRENGTH/SEQUENCES

A 3 T scanner. Localized 2D intermolecular double-quantum coherence-based MRS (iDQC-MRS).

ASSESSMENT

In addition to the conventional water and fat peaks, another four crossing peaks of the FAs were well resolved from the L4 vertebral bone marrow using iDQC-MRS technique: allylic methylene (2.0 ppm), terminal methylene (2.2 ppm), diallylic methylene (2.7 ppm), and olefinic (5.3 ppm). The monounsaturated fatty acids (MOFA) and polyunsaturated fatty acids (PUFAs) were then calculated.

STATISTICAL TESTS

Differences between PMOP and HC were investigated using the analysis of a t-test, and the relationships were investigated using regression analysis.

RESULTS

MOFAs and PUFAs fractions were significantly lower in the PMOP group compared to the HC group. In contrast, the saturated FAs fraction is significantly higher in the PMOP group. Additionally, decreased PUFAs, MOFAs were moderately negatively correlated with the volumetric bone mineral density (vBMD) in the PMOP group. Furthermore, increased SFAs in PMOP were strongly associated with vBMD.

DATA CONCLUSION

Using spectra resolution enhanced 2D iDQC-MRS technique, we observed low unsaturated FAs levels in the vertebral bone marrow of the PMOP patients. The reduced unsaturated FAs levels in PMOP may be associated with dysfunction of the balance between osteoblastogenesis and osteoclastogenesis.

LEVEL OF EVIDENCE: 2

TECHNICAL EFFICACY STAGE

1.

The Predictive Value of Early Postoperative MRI-Based Bone Marrow Parameters for Mid-Term Outcome after MACI with Autologous Bone Grafting at the Knee

OBJECTIVE

The aim of this study was to longitudinally determine the prognostic value of early postoperative quantitative 3T-MRI (magnetic resonance imaging) parameters of subchondral bone marrow for 2-year clinical and MRI outcome after matrix-associated autologous chondrocyte implantation (MACI) with autologous bone grafting (ABG) at the knee.

DESIGN

Consecutive subjects who received MACI with ABG for treatment of focal osteochondral defects received MRI follow-up 3, 6, 12, and 24 months postoperatively. Quantitative MRI included bone marrow edema-like lesion (BMEL) volume measurements and single-voxel magnetic resonance spectroscopy (MRS; n = 9) of the subchondral bone marrow. At 2-year follow-up, morphological MRI outcome included MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 scores. Clinical outcomes were assessed using Lysholm scores.

RESULTS

Among a total of 18 subjects (mean age: 28.7 ± 8.4 years, n = 14 males) with defects at the medial or lateral (n = 15 and n = 3, respectively) condyle, mean BMEL volume decreased from 4.9 cm³ at 3 months to 2.0 cm³ at 2-year follow-up (P = 0.040). MRS-based bone marrow water T2 showed a decrease from 20.7 ms at 1-year follow-up to 16.8 ms at 2-year follow-up (P = 0.040). Higher BMEL volume at 6 months correlated with lower 2-year Lysholm (R = -0.616, P = 0.015) and MOCART 2.0 scores (R = -0.567, P = 0.027). Larger early postoperative BMEL volumes at 3 months (R = -0.850, P = 0.007) and 6 months (R = -0.811, P = 0.008) correlated with lower MRS-based unsaturated lipid fractions at 2-year follow-up. Furthermore, patients with early postoperative bony defects showed worse MOCART 2.0 (P = 0.044) and Lysholm scores (P = 0.017) after 24 months.

CONCLUSION

Low subchondral BMEL volume and optimal restoration of the subchondral bone at early postoperative time points predict better 2-year clinical and MRI outcomes after MACI with ABG.

Fat unsaturation measures in tibial, subcutaneous and breast adipose tissue using short and long TE MRS at 3 T

Fat unsaturation and poly-unsaturation measures can be obtained in vivo with magnetic resonance spectroscopy (MRS) through the olefinic (≈5.4 ppm) and diallylic (≈2.8 ppm) resonances, respectively. Long echo time (TE) MRS sequences have been previously optimized for olefinic/methylene (≈1.3 ppm) or olefinic/methyl (≈0.9 ppm) measures. The objectives of this work, using a Point RESolved Spectroscopy (PRESS) sequence, are to: 1) Investigate olefinic, methyl and methylene resonance decay in subcutaneous, tibial, and breast adipose tissue to determine if a direct comparison of unsaturation measures can be made without correction for T₂ losses. 2) Assess intra-individual fat unsaturation and poly-unsaturation measures in the three adipose tissues. 3) Estimate correction factors for olefinic to methylene ratios to compensate for J-coupling and T₂ relaxation losses that take place when increasing PRESS TE from 40 ms to 200 ms (previously optimized long-TE). 4) Investigate the utility of an inversion recovery for resolving the olefinic resonance from water in adipose tissue. PRESS spectra were acquired from the three adipose regions (breast in female only) in healthy volunteers at 3 T. It was found that olefinic and methyl signal decays faster in breast tissue compared to in tibial bone marrow. Poly-unsaturation measures (diallylic/methylene) differ for tibial bone marrow compared to subcutaneous and breast adipose tissue, with average values of 1.7 ± 0.4, 2.2 ± 0.4, and 2.3 ± 0.8%, respectively. PRESS (TE = 40 ms) with an inversion recovery resolves the olefinic and water resonances in breast tissue with a signal to noise ratio approximately six times greater than that using PRESS with a TE of 200 ms. Stimulated Echo Acquisition Mode (STEAM) with a TE of 20 ms (mixing time of 20 ms) was also combined with IR to resolve the olefinic resonance from that of water is spinal bone marrow.

Quantitative 3-T Magnetic Resonance Imaging After Matrix-Associated Autologous Chondrocyte Implantation With Autologous Bone Grafting of the Knee: The Importance of Subchondral Bone Parameters

BACKGROUND

Matrix-associated autologous chondrocyte implantation (MACI) with autologous bone grafting (ABG) is an effective surgical treatment for osteochondral defects. Quantitative magnetic resonance imaging (MRI) techniques are increasingly applied as noninvasive biomarkers to assess the biochemical composition of cartilage repair tissue.

PURPOSE

To evaluate the association of quantitative MRI parameters of cartilage repair tissue and subchondral bone marrow with magnetic resonance morphologic and clinical outcomes after MACI with ABG of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Qualitative and quantitative 3 T MRI of the knee was performed in 21 patients (16 male) at 2.5 years after MACI with ABG at the medial (18/21) or lateral (3/21) femoral condyle for the treatment of osteochondral defects. Morphologic MRI sequences were assessed using MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 scores. T2 relaxation time measurements for the assessment of cartilage repair tissue (CRT2) were obtained. Single-voxel magnetic resonance spectroscopy was performed in underlying subchondral bone marrow (BM) and at both central femoral condyles. The presence of pain and Tegner scores were noted. Statistical analyses included Student t tests, correlation analyses, and multivariate regression models.

RESULTS

The mean defect size was 4.9 ± 1.9 cm². At a follow-up of 2.5 ± 0.3 years, 9 of 21 patients were asymptomatic. Perfect defect filling was achieved in 66.7% (14/21) of patients. MOCART 2.0 scores (74.1 ± 18.4) did not indicate pain (68.3 ± 19.0 [pain] vs 81.7 ± 15.4 [no pain]; P = .102). However, knee pain was present in 85.7% (6/7) of patients with deep bony defects (odds ratio, 8.0; P = .078). Relative CRT2 was higher in hypertrophic cartilage repair tissue than in repair tissue with normal filling (1.54 ± 0.42 vs 1.13 ± 0.21, respectively; P = .022). The underlying BM edema-like lesion (BMEL) volume was larger in patients with underfilling compared with patients with perfect defect filling (1.87 ± 1.32 vs 0.31 ± 0.51 cm³, respectively; P = .002). Patients with severe pain showed a higher BMEL volume (1.2 ± 1.3 vs 0.2 ± 0.4 cm³, respectively; P = .046) and had a higher BM water fraction (26.0% ± 12.3% vs 8.6% ± 8.1%, respectively; P = .026) than did patients without pain.

CONCLUSION

Qualitative and quantitative MRI parameters including the presence of subchondral defects, CRT2, BMEL volume, and BM water fraction were correlated with cartilage repair tissue quality and clinical symptoms. Therefore, the integrity of subchondral bone was associated with outcomes after osteochondral transplantation.

Resolving the omega-3 methyl resonance with long echo time magnetic resonance spectroscopy in mouse adipose tissue at 9.4 T

Tissue omega-3 (ω-3) content is biologically important to disease; however, its quantification with magnetic resonance spectroscopy in vivo is challenging due to its low concentration. In addition, the ω-3 methyl resonance (≈ 0.98 ppm) overlaps that of the non-ω-3 (≈ 0.90 ppm), even at 9.4 T. We demonstrate that a Point-RESolved Spectroscopy (PRESS) sequence with an echo time (TE) of 109 ms resolves the ω-3 and non-ω-3 methyl peaks at 9.4 T. Sequence efficacy was verified on five oils with differing ω-3 fat content; the ω-3 content obtained correlated with that measured using 16.5 T NMR (R² = 0.97). The PRESS sequence was also applied to measure ω-3 content in visceral adipose tissue of three different groups (all n = 3) of mice, each of which were fed a different 20% w/w fat diet. The fat portion of the diet consisted of low (1.4%), medium (9.0%) or high (16.4%) ω-3 fat. The sequence was also applied to a control mouse fed a standard chow diet (5.6% w/w fat, which was 5.9% ω-3). Gas chromatography (GC) analysis of excised tissue was performed for each mouse. The ω-3 fat content obtained with the PRESS sequence correlated with the GC measures (R² = 0.96). Apparent T₂ times of methyl protons were assessed by obtaining spectra from the oils and another group of four mice (fed the high ω-3 diet) with TE values of 109 and 399 ms. Peak areas were fit to a mono-exponentially decaying function and the apparent T₂ values of the ω-3 and non-ω-3 methyl protons were 906 ± 148 and 398 ± 78 ms, respectively, in the oils. In mice, the values were 410 ± 68 and 283 ± 57 ms for ω-3 and non-ω-3 fats, respectively.

Analysis of muscle, hip, and subcutaneous fat in osteoporosis patients with varying degrees of fracture risk using 3T Chemical Shift Encoded MRI

Osteoporosis (OP) is a major disease that affects 200 million people worldwide. Fatty acid metabolism plays an important role in bone health and plays an important role in bone quality and remodeling. Increased bone marrow fat quantity has been shown to be associated with a decrease in bone mineral density (BMD), which is used to predict fracture risk. Chemical-Shift Encoded magnetic resonance imaging (CSE-MRI) allows noninvasive and quantitative assessment of adipose tissues (AT). The aim of our study was to assess hip or proximal femoral bone marrow adipose tissue (BMAT), thigh muscle (MUS), and subcutaneous adipose tissue (SAT) in 128 OP subjects matched for age, BMD, weight and height with different degrees of fracture risk assessed through the FRAX score (low, moderate and high). Our results showed an increase in BMAT and in MUS in high compared to low fracture risk patients. We also assessed the relationship between fracture risk as assessed by FRAX and AT quantities. Overall, the results of this study suggest that assessment of adipose tissue via 3T CSE-MRI provides insight into the pathophysiology fracture risk by showing differences in the bone marrow and muscle fat content in subjects with similarly osteoporotic BMD as assessed by DXA, but with varying degrees of fracture risk as assessed by FRAX.

MRI Assessment of Bone Marrow Composition in Osteoporosis

PURPOSE OF REVIEW

To provide an overview on recent technical development for quantifying marrow composition using magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques, as well as a summary on recent findings of interrelationship between marrow adipose tissue (MAT) and skeletal health in the context of osteoporosis.

RECENT FINDINGS

There have been significant technical advances in reliable quantification of marrow composition using MR techniques. Cross-sectional studies have demonstrated a negative correlation between MAT and bone, with trabecular bone associating more strongly with MAT than cortical bone. However, longitudinal studies of MAT and bone are limited. MAT contents and composition have been associated with prevalent vertebral fracture. The evidence between MAT and clinical fracture is more limited, and, to date, no studies have reported on the relationship between MAT and incident fracture. Increasing evidence suggests a dynamic role of marrow fat in skeletal health. Reliable non-invasive quantification of marrow composition will facilitate developing novel treatment strategies for osteoporosis.

Chemical-Shift-Encoded Magnetic Resonance Imaging and Spectroscopy to Reveal Immediate and Long-Term Multi-Organs Composition Changes of a 14-Days Periodic Fasting Intervention: A Technological and Case Report

Objectives: The aim of this study was to investigate the feasibility of measuring the effects of a 14-day Periodic Fasting (PF) intervention (<200 cal) on multi-organs of primary interest (liver, visceral/subcutaneous/bone marrow fat, muscle) using non-invasive advanced magnetic resonance spectroscopic (MRS) and imaging (MRI) methods.

Methods: One subject participated in a 14-day PF under daily supervision of nurses and specialized physicians, ingesting a highly reduced intake: 200 Kcal/day coupled with active walking and drinking at least 3 L of liquids/day. The fasting was preceded by a 7-day pre-fasting vegetarian period and followed by 14 days of stepwise reintroduction of food. The longitudinal study collected imaging and biological data before the fast, at peak fasting, and 7 days, 1 month, and 4 months after re-feeding. Body fat mass in the trunk, abdomen, and thigh, liver and muscle mass, were respectively computed using advanced MRI and MRS signal modeling. Fat fraction, MRI relativity index T2^* and susceptibility (Chi), as well as Fatty acid composition, were calculated at all-time points.

Results: A decrease in body weight (BW: −9.5%), quadriceps muscle volume (−3.2%), Subcutaneous and Visceral Adipose Tissue (SAT −34.4%; VAT −20.8%), liver fat fraction (PDFF = 1.4 vs. 2.6 % at baseline) but increase in Spine Bone Marrow adipose tissue (BMAT) associated with a 10% increase in global adiposity fraction (PDFF: 54.4 vs. 50.9%) was observed. Femoral BMAT showed minimal changes compared to spinal level, with a slight decrease (−3.1%). Interestingly, fatty acid (FA) pattern changes differed depending on the AT locations. In muscle, all lipids increased after fasting, with a greater increase of intramyocellular lipid (IMCL: from 2.7 to 6.3 mmol/kg) after fasting compared to extramyocellular lipid (EMCL: from 6.2 to 9.5 mmol/kg) as well as Carnosine (6.9 to 8.1 mmol/kg). Heterogenous and reverse changes were also observed after re-feeding depending on the organ.

Conclusion: These results suggest that investigating the effects of a 14-day PF intervention using advanced MRI and MRS is feasible. Quantitative MR indexes are a crucial adjunct to further understanding the effective changes in multiple crucial organs especially liver, spin, and muscle, differences between adipose tissue composition and the interplay that occurs during periodic fasting.

Chemical shift-encoded MRI for assessment of bone marrow adipose tissue fat composition: Pilot study in premenopausal versus postmenopausal women

OBJECT

To quantify and compare subregional proximal femur bone marrow fat composition in premenopausal and postmenopausal women using chemical shift-encoded-MRI (CSE-MRI).

MATERIALS AND METHODS

A multi gradient-echo sequence at 3 T was used to scan both hips of premenopausal (n = 9) and postmenopausal (n = 18) women. Subregional fat composition (saturation, poly-unsaturation, mono-unsaturation) was quantitatively assessed in the femoral head, femoral neck, Ward's triangle, greater trochanter, and proximal shaft in bone marrow adipose tissue and separately within red and yellow marrow adipose tissue.

RESULTS

Significant differences in fat composition in postmenopausal compared to premenopausal women, which varied depending on the subregion analyzed, were found. Within both whole and yellow marrow adipose tissue, postmenopausal women demonstrated higher saturation (+14.7% to +43.3%), lower mono- (-11.4% to -33%) and polyunsaturation (-52 to -83%) (p < 0.05). Within red marrow adipose tissue, postmenopausal women demonstrated lower fat quantity (-16% to -24%) and decreased polyunsaturation (-80 to -120%) in the femoral neck, greater trochanter, and Ward's triangle (p < 0.05).

CONCLUSION

CSE-MRI can be used to detect subregional differences in proximal femur marrow adipose tissue composition between pre- and post-menopausal women in clinically feasible scan times.

Reliable quantification of marrow fat content and unsaturation level using in vivo MR spectroscopy

PURPOSE

To develop a novel technique for reliable quantification of bone marrow fat content and composition using in vivo MR spectroscopy (MRS).

METHODS

An MRS quantification method combining both advantages of Voigt line shape model and time-domain analysis was developed. The proposed method was tested using computer-simulated data and in vivo data acquired at lumbar vertebral bodies of 23 subjects (age, 83.8 ± 3.7 y; male, n = 13; female, n = 10) from L1 to L4. Reliability and reproducibility were calculated for the quantification results. Comparisons between the proposed method and some conventional methods were conducted.

RESULTS

Low mean absolute percentage errors and low mean coefficients of variation for computer simulations suggest that the proposed method is accurate and precise. By using this method, marrow fat content can be quantified reliably, even for data with low spectral resolution and low signal-to-noise ratio (SNR). Unsaturation level can be reliably quantified for data with moderate spectral resolution and moderate SNR. Results obtained from in vivo data using the proposed method demonstrated better model fit than conventional methods.

CONCLUSION

The method proposed in this study has better performance than conventional methods in the quantification of bone marrow MRS data and has great potential for wide applications of studying marrow fat content and composition. Magn Reson Med 79:1722-1729, 2018. © 2017 International Society for Magnetic Resonance in Medicine.