Techniques and Applications of Magnetic Resonance Imaging for Studying Brown Adipose Tissue Morphometry and Function

Karampinos, Dimitrios C.; Weidlich, Dominik; Wu, Mingming; Hu, Houchun H.; Franz, Daniela

doi:10.1007/164_2018_158

Cited by 20 publications

(37 citation statements)

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“…In bone marrow, MR techniques have been emerging for measuring bone marrow water‐fat composition but techniques are lacking for the assessment of bone marrow adipose tissue (BMAT) microstructure, which is needed to differentiate between regulated BMAT and constitutive BMAT . In human adipose tissue depots containing brown adipose tissue, techniques assessing lipid droplet microstructure are needed to overcome the partial volume effects on the fat fraction measurements in regions containing both white and brown adipose tissue . The present results show that lipid droplet size measurements can be validated in water–fat phantoms and applied with good reproducibility in the tibial bone marrow.…”

Section: Discussionmentioning

confidence: 82%

Measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion‐weighted MRS at 3T

Weidlich

Honecker

Gmach

et al. 2019

Magnetic Resonance in Med

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Purpose The in vivo probing of restricted diffusion effects in large lipid droplets on a clinical MR scanner remains a major challenge due to the need for high b‐values and long diffusion times. This work proposes a methodology to probe mean lipid droplet sizes using diffusion‐weighted MRS (DW‐MRS) at 3T. Methods An analytical expression for restricted diffusion was used. Simulations were performed to evaluate the noise performance and the influence of particle size distribution. To validate the method, oil‐in‐water emulsions were prepared and examined using DW‐MRS, laser deflection and light microscopy. The tibia bone marrow was scanned in volunteers to test the method repeatability and characterize microstructural differences at different locations. Results The simulations showed accurate and precise droplet size estimation when a sufficient SNR is reached with minor dependence on the size distribution. In phantoms, a good correlation between the measured droplet sizes by DW‐MRS and by laser deflection (R 2 = 0.98; P = 0.01) and microscopy (R 2 = 0.99; P < 0.01) measurements was obtained. A mean coefficient of variation of 11.5 % was found for the lipid droplet diameter in vivo. The average diameter was smaller at a proximal (50.1 ± 7.3 µm) compared with a distal tibia location (61.1 ± 6.8 µm) ( P < 0.01). Conclusion The presented methods were able to probe restricted diffusion effects in lipid droplets using DW‐MRS and to estimate lipid droplet size. The methodology was validated using phantoms and the in vivo feasibility in bone marrow was shown based on a good repeatability and findings in agreement with literature.

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Section: Discussionmentioning

confidence: 82%

Measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion‐weighted MRS at 3T

Weidlich

Honecker

Gmach

et al. 2019

Magnetic Resonance in Med

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“…Intensive research over the past years has changed the traditional view of adipose tissue from being an inert, lipid-storing depot to a highly dynamic, endocrine organ. The growing interest for a better understanding of brown adipose tissue (BAT) was triggered by the discovery of active BAT on 18 F-fluoro-2-deoxy-D-glucose ( 18 F-FDG) positron emission tomography (PET) scans in adult oncology patients [2].…”

Section: Introductionmentioning

confidence: 99%

“…The high glucose consumption of activated BAT leads to a large number of studies, using 18 F-FDG PET as a surrogate marker for its metabolic activity [5][6][7]. Most of these studies, looking into the prevalence and factors that correlated with high BAT activity, were done on retrospective data and showed that active BAT was more commonly seen on 18 F-FDG PET scans in winter than in summer, in women than in man, and in normal weight vs obese patients [5,[8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…An increasing number of prospective trials, investigating the activity of BAT with 18 F-FDG PET, were published in the last few years [13][14][15], however without any accepted standardization of the protocols [16]. Therefore, a suggestion on how to image and quantify BAT activity was published in 2016: the Brown Adipose Reporting Criteria in Imaging Studies (BARCIST 1.0) [17].…”

Section: Introductionmentioning

confidence: 99%

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Low-dose 18F-FDG TOF-PET/MR for accurate quantification of brown adipose tissue in healthy volunteers

et al. 2020

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Background: Positron emission tomography (PET) is increasingly applied for in vivo brown adipose tissue (BAT) research in healthy volunteers. To limit the radiation exposure, the injected 18 F-FDG tracer dose should be as low as possible. With simultaneous PET/MR imaging, the radiation exposure due to computed tomography (CT) can be avoided, but more importantly, the PET acquisition time can often be increased to match the more extensive magnetic resonance (MR) imaging protocol. The potential gain in detected coincidence counts, due to the longer acquisition time, can then be applied to decrease the injected tracer dose. The aim of this study was to investigate the minimal 18 F-FDG dose for a 10-min time-of-flight (TOF) PET/MR acquisition that would still allow accurate quantification of supraclavicular BAT volume and activity. Methods: Twenty datasets from 13 volunteers were retrospectively included from a prospective clinical study. PET emission datasets were modified to simulate step-wise reductions of the original 75 MBq injected dose. The resulting PET images were visually and quantitatively assessed and compared to a 4-min reference scan. For the visual assessment, the image quality and artifacts were scored using a 5-point and a 3-point Likert scale. For the quantitative analysis, image noise and artifacts, BAT metabolic activity, BAT metabolic volume (BMV), and total BAT glycolysis (TBG) were investigated. Results: The visual assessment showed still good image quality for the 35%, 30%, and 25% activity reconstructions with no artifacts. Quantitatively, the background noise was similar to the reference for the 35% and 30% activity reconstructions and the artifacts started to increase significantly in the 25% and lower activity reconstructions. There was no significant difference in supraclavicular BAT metabolic activity, BMV, and TBG between the reference and the 35% to 20% activity reconstructions. Conclusions: This study indicates that when the PET acquisition time is matched to the 10-min MRI protocol, the injected 18 F-FDG tracer dose can be reduced to approximately 19 MBq (25%) while maintaining image quality and accurate supraclavicular BAT quantification. This could decrease the effective dose from 1.4 mSv to 0.36 mSv.

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“…MR-based techniques provide superior resolution, contrast, and quantitative information of BAT. 8,[28][29][30][31][32] The fat fraction (FF) imaging has been well established to investigate fat metabolism during activation of BAT in rodents [28][29][30]32 and clinical studies. [33][34][35][36][37] Dynamic contrast-enhanced (DCE)-MRI is sensitive for changes in tissue microvascular environment and physiological parameters of the tissue including the kinetics of blood flow.…”

Section: Introductionmentioning

confidence: 99%

Dynamic contrast‐enhanced MRI of brown and beige adipose tissues

Yaligar

Verma

Gopalan

et al. 2019

Magnetic Resonance in Med

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Purpose The vascular blood flow in brown adipose tissue (BAT) is important for handling triglyceride clearance, increased blood flow and oxygenation. We used dynamic contrast‐enhanced (DCE)‐MRI and fat fraction (FF) imaging for investigating vascular perfusion kinetics in brown and beige adipose tissues with cold exposure or treatment with β3‐adrenergic agonist. Methods FF imaging and DCE‐MRI using gadolinium‐diethylenetriaminepentaacetic acid were performed in interscapular BAT (iBAT) and beige tissues using male Wister rats (n = 38). Imaging was performed at thermoneutral condition and with either cold exposure, treatment with pharmacological agent CL‐316,243, or saline. DCE‐MRI and FF data were co‐registered to enhance the understanding of metabolic activity. Results Uptake of contrast agent in activated iBAT and beige tissues were significantly (P < .05) higher than nonactivated iBAT. The Ktrans and kep increased significantly in iBAT and beige tissues after treatment with either cold exposure or β3‐adrenergic agonist. The FF decreased in activated iBAT and beige tissues. The Ktrans and FF from iBAT and beige tissues were inversely correlated (r = 0.97; r = 0.94). Significant increase in vascular endothelial growth factor expression and Ktrans in activated iBAT and beige tissues were in agreement with the increased vasculature and vascular perfusion kinetics. The iBAT and beige tissues were validated by measuring molecular markers. Conclusion Increased Ktrans and decreased FF in iBAT and beige tissues were in agreement with the vascular perfusion kinetics facilitating the clearance of free fatty acids. The methodology can be extended for the screening of browning agents.

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Techniques and Applications of Magnetic Resonance Imaging for Studying Brown Adipose Tissue Morphometry and Function

Cited by 20 publications

References 100 publications

Measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion‐weighted MRS at 3T

Measuring large lipid droplet sizes by probing restricted lipid diffusion effects with diffusion‐weighted MRS at 3T

Low-dose 18F-FDG TOF-PET/MR for accurate quantification of brown adipose tissue in healthy volunteers

Dynamic contrast‐enhanced MRI of brown and beige adipose tissues

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