Human brown fat radiodensity indicates underlying tissue composition and systemic metabolic health.

Human brown fat radiodensity indicates underlying tissue composition and systemic metabolic health.

J Clin Endocrinol Metab. 2017 Mar 24;:

Authors: Din MU, Raiko J, Saari T, Saunavaara V, Kudomi N, Solin O, Parkkola R, Nuutila P, Virtanen KA

Abstract
Context: Metabolic imaging studying brown adipose tissue (BAT) physiology has increased, where computed tomography (CT) is commonly used as an anatomical reference for metabolic PET (positron emission tomography) imaging. However, the capacity of CT to provide metabolic information has been underexploited.
Objective: To evaluate whether CT radiodensity of BAT could non-invasively estimate underlying tissue morphology, regarding amount of stored triglycerides. Further, could the alteration in tissue characteristics due to cold stimulus, as a marker for active BAT, be detected with radiodensity. And, whether BAT can be differentiated from white adipose tissue (WAT) solely using CT based measurements.
Design, Setting and Participants: A cross-sectional study evaluating sixty-six healthy human subjects with CT, PET and 1H-magnetic resonance spectroscopy (1H-MRS).
Main Outcome Measures: BAT radiodensity was measured with CT. BAT stored triglyceride content was measured with 1H-MRS. Arterial blood volume in BAT, as a marker of tissue vascularity, was measured with [15O]H2O, along with glucose or fatty acid uptake using [18F]FDG or [18F]FTHA PET imaging, respectively.
Results: BAT radiodensity was found to be correlating with tissue-retained blood and triglyceride content. Cold stimulus induced an increase in BAT radiodensity. Active BAT depots had higher radiodensity than both non-active BAT and WAT. BAT radiodensity associated with systemic metabolic health parameters.
Conclusion: BAT radiodensity can be used as a marker of underlying tissue morphology. Active BAT can be identified using CT, exploiting tissue composition information. Moreover, BAT radiodensity provides an insight in whole-body systemic metabolic health.

PMID: 28368474 [PubMed - as supplied by publisher]

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