Fig. 5: Cold exposure leads to a selective uptake of inhaled hyperpolarized xenon in supraclavicular human BAT.

a HPXe spectrum acquired at thermoneutrality, 16 s from the beginning of the breath-hold, on a 25-30 y.o. female with a BMI of 23 kg/m². b HPXe spectrum acquired on the same participant during cold exposure, also 16 s from the beginning of the breath-hold. c Zoomed-in view of spectra shown in (a) and (b) showing selective increase of the lipid-dissolved xenon (LDX) peak, normalized to the corresponding gas-phase peak, during cold exposure. d Plot showing the expected time-dependent signal function (see ref. ⁵⁶) fitted to the acquired LDX signal. e Hyperpolarized xenon (HPXe) MR image acquired on the same participant after HPXe exhalation, over the course of 16 s (field of view of 300 × 300, and a matrix size of 32 ×4 reconstructed to 64 ×8). f Corresponding anatomical, fat-only, ¹H image acquired on the same participant using the dual-tuned ¹H/¹²⁹Xe coil. g Overlay of the HPXe image shown in (e) onto the corresponding anatomical fat-only ¹H image shown in (f). h Coronal view of the ¹⁸F-FDG maximum-intensity-projection (MIP) image. Dotted red line indicates the location of the corresponding fused image shown in (i). i Overlay of the axial ¹⁸F-FDG map onto the corresponding anatomical fat-only axial ¹H image showing increased glucose uptake in supraclavicular fat, where most of the ¹²⁹Xe signal was observed.