Imaging Techniques for Brown Adipose Tissue Characterization

Brown adipose tissue (BAT) serves a central role in thermogenesis and energy balance, rendering its non-invasive visualisation and quantification of prime importance in metabolic research. Contemporary approaches span molecular imaging, anatomical mapping and optical methods, each probing distinct facets of BAT biology. Positron emission tomography (PET) coupled with computed tomography (CT) remains a gold standard for detecting radiotracer uptake reflective of metabolic activity, while xenon-enhanced CT and dynamic contrast-enhanced ultrasound (DCE-US) afford complementary measures of perfusion and tissue density. Magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques—including proton density fat fraction mapping, diffusion-weighted imaging and multinuclear methods—enable detailed assessment of lipid content, microstructure and thermogenic function without ionising radiation. Optical modalities such as diffuse reflectance spectroscopy and multispectral imaging exploit tissue absorption and scattering to monitor browning processes in real time. Integration of these modalities facilitates a holistic characterisation of BAT distribution, activation state and compositional changes, informing therapeutic strategies for obesity and metabolic disorders.

Research from Nature Portfolio

Recent studies have harnessed a multimodal framework to delineate the browning of white adipose depots. One investigation combined 18F-FDG PET/CT, conventional CT, xenon-enhanced CT and DCE-US in a murine model to reveal heterogeneous increases in tissue water content and perfusion during pharmacologically induced browning. A separate work applied a cooling–reheating MRI protocol in humans to demonstrate sustained decreases in fat fraction within the supraclavicular BAT depot, attributing these changes primarily to lipid consumption rather than perfusion shifts. In parallel, diffuse reflectance spectroscopy and multispectral imaging were employed to track the time-dependent conversion of white to brown-like adipocytes in mice, offering a rapid, cost-effective optical readout that correlated closely with molecular markers of browning.

Research from all publishers

A comprehensive review has summarised the principles, advantages and limitations of optical imaging methods for probing brown and beige fat activation, guiding selection of optimal light-based modalities for non-invasive assessments. In clinical imaging, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) have been evaluated on 18F-FDG PET/CT scans, showing superior sensitivity and specificity compared with SUVmax alone for quantifying BAT activation intensity. Additionally, an in-depth appraisal of MRI and MRS techniques has outlined the use of proton density fat fraction mapping, diffusion imaging and intermolecular multiple quantum coherence, alongside multinuclear spectroscopy (31P, 2H, 13C, 129Xe), to distinguish BAT from white adipose tissue and to yield both morphological and functional insights.

Imaging Techniques for Brown Adipose Tissue Characterization publication trend

The graph below shows the total number of articles in imaging techniques for brown adipose tissue characterization across all publications each year (not limited to Nature Index journals).

Technical terms

Positron emission tomography (PET): Non-invasive imaging technique that detects gamma rays emitted by radiotracers to map regional metabolic activity.

Computed tomography (CT): Imaging method using X-rays to generate cross-sectional anatomical images based on tissue attenuation.

Magnetic resonance imaging (MRI): Non-invasive modality employing magnetic fields and radiofrequency pulses to produce high-resolution anatomical and functional images.

Fat fraction: Proportion of lipid signal relative to total signal in a region, used to quantify tissue lipid content.

Dynamic contrast-enhanced ultrasound (DCE-US): Ultrasound technique assessing tissue perfusion by tracking microbubble contrast agents over time.

Metabolic tumour volume (MTV): Total volume of tissue exhibiting elevated tracer uptake on PET, here applied to active brown fat.

Total lesion glycolysis (TLG): Combined metric of lesion volume and mean radiotracer uptake, providing an aggregate measure of metabolic activity.

References

1. Optical imaging for brown or beige adipose tissue. View (2024).
2. In-vivo detection of white adipose tissue browning: a multimodality imaging approach. Scientific Reports (2023).
3. Are MTV and TLG Accurate for Quantifying the Intensity of Brown Adipose Tissue Activation?. Biomedicines (2024).
4. Magnetic Resonance Imaging Techniques for Brown Adipose Tissue Detection. Frontiers in Endocrinology (2020).
5. Magnetic Resonance Imaging Cooling-Reheating Protocol Indicates Decreased Fat Fraction via Lipid Consumption in Suspected Brown Adipose Tissue. PLOS ONE (2015).
6. Diffuse Optical Spectroscopy and Imaging to Detect and Quantify Adipose Tissue Browning. Scientific Reports (2017).