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Impaired Cold Stimulated Supraclavicular Brown Adipose Tissue Activity in Young Boys with Obesity

Basma A. Ahmed et al. Impaired Cold Stimulated Supraclavicular Brown Adipose Tissue Activity in Young Boys with Obesity Diabetes.

Publication Date
March 16, 2022

How Analyze was Used
“Post-imaging analysis: Segmentation and analysis of all MR images were conducted using Analyze Pro 1.0 (AnalyzeDirect, Overland Park, KS, USA) by one reader (BA). The SCV region was segmented (the adipose tissue bound by the sternocleidomastoid medially, trapezius posteriorly, and clavicle inferiorly between the C5-C6 and T1-T2 disks) as previously described. The image analysis was consistent with our previous publications but described briefly here. A fat mask was generated from the fat-only images and applied to the PDFF map at the C7-T1 disc to isolate the adipose tissues and exclude background noise from the MRI images. Then a 30 to 100% FF threshold was applied to the PDFF images. The region of interest (ROI) was manually drawn over the SCV region as defined above. A one-time 2D erosion (1×3 voxels) was applied to the ROIs to correct for partial volume effects. T2∗ images were generated from the R2∗ data using the relationship: T2∗ = 1/R2∗. A T2∗ mask was applied to the FF map to differentiate BAT from white adipose tissue (WAT) by isolating voxels with a T2∗ between 2 and 25ms. The lower range of 2ms was selected due to the MRI sequence’s limitation in detecting very low T2∗ values and the higher range was based on a published report that tissue with a T2∗ value of ≥ 26ms consists mostly of muscle, fluid, or white adipocytes. All voxels that satisfied the above criteria were averaged and classified as SCV PDFF.
To evaluate BAT activity accounting for the pre-cold SCV PDFF, the percent change in SCV PDFF was
calculated as [(pre-cold SCV PDFF – post-cold SCV PDFF)/ (pre-cold SCV PDFF)] * 100 and is noted as cold-induced percent decline in SCV PDFF – a measure of BAT activity. For comparison with SCV BAT, the PDFF of the subcutaneous adipose tissue (SAT) in the posterior neck region (neck SAT) was analyzed at three MRI slices: C5-C6, C6-C7, and T1-T2 using manual tracing and the criteria that were used for SCV BAT.”

Childhood obesity, Brown adipose tissue, BAT, Cold-induced supraclavicular, Proton density fat fraction, PDFF, MRI, Anthropometry, Body composition, Visceral fat, VAT, Subcutaneous adipose tissue, SAT

Author Affiliation(s)
McMaster University, Hamilton, Ontario, Canada

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