A Flexible Graphite–Silicone Pad for Improved Fat Suppression in Cervical Spine <scp>MRI</scp> at 5 T via Passive <scp> <i>B</i> ₀ </scp> Shimming

ABSTRACT Purpose Susceptibility‐induced inhomogeneity at the posterior neck degrades spectral fat suppression in cervical spine MRI at 5 T and above. We describe a flexible graphite–silicone pad for passive shimming and assess its effect on field homogeneity and fat‐suppressed imaging alongside the scanner's active shim. Methods Pads were fabricated by dispersing high‐purity graphite powder in a biocompatible silicone elastomer and casting the mixture in a 3D‐printed mold shaped to the posterior neck and head–neck receive coil. Five graphite‐to‐silicone mass ratios (1.5:100 through 8:100) were screened in one volunteer on a 5 T scanner using dual‐echo mapping and fat‐suppressed ‐ and ‐weighted FSE. The selected ratio (4.5:100) was evaluated in five healthy volunteers under volume‐based active shimming, with and without the pad in randomized order. Results In the screening volunteer under Volume shimming, the 4.5:100 pad reduced the posterior‐neck field from 0.740 to 0.458 ppm, a 38% reduction at matched shim mode. Across the five validation subjects, decreased in every case under Volume shimming, from to ppm (individual reductions 41%–55%). Residual hyperintense fat seen with the standard pad was no longer present on sagittal ‐ or ‐weighted images, and the improvement extended to the supraclavicular region on coronal ‐weighted images. Conclusion A flexible graphite–silicone pad complements active shimming and improves spectral fat suppression in cervical spine MRI at 5 T. Evaluation in patients and on EPI‐based sequences remains to be done.