Motion-robust proton density fat fraction and T 2 ∗ mapping in supraclavicular adipose tissue using radial...

Accurate quantification of proton density fat fraction (PDFF) and ${T_2}^{\ast }$ in the supracalvicular (SCV) fossa is critical for studying brown adipose tissue (BAT), but is challenged by respiratory motion-induced $B_0$ fluctuations. This study compares conventional Cartesian imaging to a radial stack-of-stars (SoS) trajectory, with and without retrospective temporal $B_0$ correction, in terms of PDFF and ${T_2}^{\ast }$ mapping precision.

Motion-induced $B_0$ fluctuations and tissue displacement were modeled using a digital anatomical phantom. Both Cartesian and radial SoS trajectories were simulated, with temporal $B_0$ correction, relying on oversampling of the k-space center, applied to the radial SoS data. Additionally, repeated in vivo scans were performed in four volunteers using both trajectories. PDFF and ${T_2}^{\ast }$ were quantified across repetitions.

Simulations demonstrated smaller PDFF and ${T_2}^{\ast }$ errors in radial SoS compared to Cartesian imaging under the influence of simulated motion effects. In the simulations, the mean absolute PDFF error decreased from ${1.07\%}_{\text{PDFF}}$ with Cartesian to ${0.47\%}_{\text{PDFF}}$ with radial SoS, and the ${T_2}^{\ast }$ error decreased from 7.50 ms to 3.37 ms. In vivo, radial SoS provided higher repeatability for both parameters compared to Cartesian acquisitions, as measured by the inter-scan coefficient of variation. Retrospective temporal $B_0$ correction further improved the repeatability of ${T_2}^{\ast }$ quantification.

Radial SoS imaging improves motion robustness and repeatability of PDFF and ${T_2}^{\ast }$ quantification in the SCV fossa compared to Cartesian acquisitions. Incorporating retrospective temporal $B_0$ correction further enhances ${T_2}^{\ast }$ reliability and may strengthen the precision of BAT activation studies.