Magnetic resonance in medicine · 2026
A Flexible Graphite-Silicone Pad for Improved Fat Suppression in Cervical Spine MRI at 5 T via Passive B0 Shimming.
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Yang Yihan, Liu Ziyu, Hong Haotian, Zhang Weijun, Ren Zhihua
Аннотация
PURPOSE: Susceptibility-induced B 0 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 B 0 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 B 0 mapping and fat-suppressed T 1 - and T 2 -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 σ from 0.740 to 0.458 ppm, a 38% reduction at matched shim mode. Across the five validation subjects, σ decreased in every case under Volume shimming, from 0.911 ± 0.117 to 0.455 ± 0.054 ppm (individual reductions 41%-55%). Residual hyperintense fat seen with the standard pad was no longer present on sagittal T 1 - or T 2 -weighted images, and the improvement extended to the supraclavicular region on coronal T 1 -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.
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 B 0 mapping and fat-suppressed T 1 - and T 2 -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 σ from 0.740 to 0.458 ppm, a 38% reduction at matched shim mode. Across the five validation subjects, σ decreased in every case under Volume shimming, from 0.911 ± 0.117 to 0.455 ± 0.054 ppm (individual reductions 41%-55%). Residual hyperintense fat seen with the standard pad was no longer present on sagittal T 1 - or T 2 -weighted images, and the improvement extended to the supraclavicular region on coronal T 1 -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.