Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Department of Diagnostic Imaging, Akershus University Hospital, Lørenskog, Norway.
Sci Rep. 2020 Sep 14;10(1):15029. doi: 10.1038/s41598-020-71623-5.
Metabolic imaging of the human brain by in-vivo magnetic resonance spectroscopic imaging (MRSI) can non-invasively probe neurochemistry in healthy and disease conditions. MRSI at ultra-high field (≥ 7 T) provides increased sensitivity for fast high-resolution metabolic imaging, but comes with technical challenges due to non-uniform B field. Here, we show that an integrated RF-receive/B-shim (AC/DC) array coil can be used to mitigate 7 T B inhomogeneity, which improves spectral quality and metabolite quantification over a whole-brain slab. Our results from simulations, phantoms, healthy and brain tumor human subjects indicate improvements of global B homogeneity by 55%, narrower spectral linewidth by 29%, higher signal-to-noise ratio by 31%, more precise metabolite quantification by 22%, and an increase by 21% of the brain volume that can be reliably analyzed. AC/DC shimming provide the highest correlation (R = 0.98, P = 0.001) with ground-truth values for metabolite concentration. Clinical translation of AC/DC and MRSI is demonstrated in a patient with mutant-IDH1 glioma where it enables imaging of D-2-hydroxyglutarate oncometabolite with a 2.8-fold increase in contrast-to-noise ratio at higher resolution and more brain coverage compared to previous 7 T studies. Hence, AC/DC technology may help ultra-high field MRSI become more feasible to take advantage of higher signal/contrast-to-noise in clinical applications.
通过活体磁共振波谱成像（MRSI）对人脑进行代谢成像，可以非侵入性地探测健康和疾病状态下的神经化学物质。超高磁场（≥7 T）的 MRSI 提供了更高的灵敏度，可实现快速高分辨率代谢成像，但由于非均匀 B 场，也带来了技术挑战。在这里，我们展示了集成的 RF 接收/B 调谐（AC/DC）阵列线圈可用于减轻 7 T 的 B 不均匀性，这可以改善整个脑片的光谱质量和代谢物定量。我们通过模拟、体模、健康和脑肿瘤人类受试者的结果表明，全局 B 均匀性提高了 55%，谱线宽度变窄了 29%，信噪比提高了 31%，代谢物定量更精确了 22%，可可靠分析的脑体积增加了 21%。AC/DC 调谐与代谢物浓度的真实值具有最高的相关性（R=0.98，P=0.001）。AC/DC 和 MRSI 的临床转化在一名携带突变 IDH1 的脑胶质瘤患者中得到了证明，与之前的 7 T 研究相比，它可以在更高的分辨率下成像 D-2-羟基戊二酸致癌代谢物，对比噪声比提高了 2.8 倍，脑覆盖范围也更大。因此，AC/DC 技术可能有助于超高磁场 MRSI 更可行地利用更高的信号/对比噪声比进行临床应用。
