Department of Radiology and Biomedical Imaging, University of California , San Francisco, California 94143, United States.
Department of Neurological Surgery, University of California , San Francisco, California 94122, United States.
ACS Chem Neurosci. 2018 Jan 17;9(1):130-137. doi: 10.1021/acschemneuro.7b00286. Epub 2017 Oct 16.
Three-dimensional proton magnetic resonance spectroscopic imaging (MRSI) is a powerful non-invasive tool for characterizing spatial variations in metabolic profiles for patients with glioma. Metabolic parameters obtained using this technique have been shown to predict treatment response, disease progression, and transformation to a more malignant phenotype. The availability of ultra-high-field MR systems has the potential to improve the characterization of metabolites. The purpose of this study was to compare the metabolite profiles acquired with conventional long echo time (TE) MRSI at 3T with those obtained with short TE MRSI at 3T and 7T in patients with glioma. The data acquisition parameters were optimized separately for each echo time and field strength to obtain volumetric coverage within clinically feasible data acquisition times of 5-10 min. While a higher field strength did provide better detection of metabolites with overlapping peaks, spatial coverage was reduced and the use of inversion recovery to reduce lipid precluded the detection of lipid in regions of necrosis. For serial evaluation of large, heterogeneous lesions, the use of 3T short TE MRSI may thus be preferred. Despite the limited number of metabolites that it is able to detect, the use of 3T long TE MRSI gives the best contrast in choline/N-acetyl aspartate between normal appearing brain and tumor and also allows the separate detection of lactate and lipid. It may therefore be preferred for serial evaluation of patients with high-grade glioma and for detection of malignant transformation in patients with low-grade glioma.
三维质子磁共振波谱成像（MRSI）是一种强大的无创工具，可用于描绘胶质瘤患者代谢谱的空间变化。使用该技术获得的代谢参数已被证明可预测治疗反应、疾病进展和向更恶性表型的转化。超高场磁共振系统的可用性有可能改善代谢物的特征。本研究的目的是比较在 3T 时使用常规长回波时间（TE）MRSI 获得的代谢谱与在 3T 和 7T 时使用短 TE MRSI 获得的代谢谱在胶质瘤患者中的差异。针对每个回波时间和场强分别优化了数据采集参数，以在 5-10 分钟的临床可行数据采集时间内获得容积覆盖。虽然更高的场强确实可以更好地检测重叠峰的代谢物，但空间覆盖范围减小，并且使用反转恢复来减少脂质会使坏死区域的脂质无法检测到。对于大型、异质病变的连续评估，因此可能更倾向于使用 3T 短 TE MRSI。尽管它能够检测到的代谢物数量有限，但使用 3T 长 TE MRSI 可以在正常脑区和肿瘤之间获得最佳的胆碱/N-乙酰天冬氨酸对比度，并且还可以单独检测到乳酸盐和脂质。因此，它可能更适合高级别胶质瘤患者的连续评估以及检测低级别胶质瘤患者的恶性转化。
