脑肿瘤的氢质子磁共振波谱研究

Study on Proton Magnetic Resonance Spectroscopy for Brain Tumors

目的：探讨氢质子磁共振渡谱（^1H—MRS）在脑肿瘤诊断、鉴别诊断中的价值以厦对胶质瘤分级的可行性。方法：对40例脑肿瘤患者行^1H-MRS检查，均经病理检查明确诊断；其中低级别（Ⅰ～Ⅱ级）星形细胞瘤15例，高级别（Ⅲ～Ⅳ级）星形细胞瘤5例，脑膜瘤13例，转移瘤7倒；采用点分辨波谱（PRESS）序列定位技术。获得单体素波谱；将NAA／Cr、Cho／Cr及NAA／Cho等指标按病理类型分组进行分析。所有病例均以对侧相应部位的正常脑组织作为自身对照。结果：脑肿瘤的^1H-MRS表现与正常脑组织明显不同（P〈0．05），表现为Cho／Cr比值升高，NAA／Cr和NAA／Cho比值下降。不同类型、不同级别脑肿瘤之间的^1H—MRS表现也存在着差异。脑膜瘤较转移瘤、低级别及高级别星形细胞瘤具有更高的Cho／Cr比值和更低的NAp/Cho、NAp/Cr比值（P〈0．05）。低级别星形细胞瘤NAA／Cho及NAA／Cr比值高于转移瘤及高级别星形细胞瘤（P〈0．05），可资鉴别。转移瘤和高级别星形细胞瘤^1H-MRS表现相似。Lac的存在不是肿瘤恶性的可靠标志。结论：^1H-MRS可提供组织生化和代谢方面的信息，提高了医学影像对肿瘤组织学分型度病理学分级的水平。

Objective：To evaluate the role of proton magnetic resonance spectroscopy （^1H-MRS） for characterization of brain tumors and to ascertain its reliability in grading of gliomas. Methods：^1H-MRS was performed in 40 cases with pathologically proven brain tumors, including 15 low-grade astrocytomas （gradeⅠ-Ⅱ）, 5 high-grade astrocytomas （grade Ⅲ-Ⅳ）, 13 menin giomas and 7 metastasis. Single-voxel spectra were acquired using a point-resolved spectroscopic （PRESS） pulse sequence as part of the Probe. The ratios of NAA/Cr, Cho/Cr and NAA/Cho were compared with the histologic type of the lesions. Corresponding spectra obtained from normal-appearing brain parenchyma in all cases were used as control group. Results： All tumor spectra, characterized by dropping of NAA/Cr and NA.A/Cho ratios and elevating of Cho/NA.A ratio, were remarkably different from spectra from normal brain tissue（P〈0. 05）. Spectra obtained from different tumors exhibited differences from each other. NAA/Cr and NAA/Cho ratios were significantly lower and Cho/Cr ratio was significantly higher in meningiomas than in metastasis, low-grade and high-grade astrocytomas（P〈0. 05）. High-grade astroeytornas were differentiated from lowgrade ones by lower NAA/Cr and NAA/Cho ratios（P〈0.05）. The spectra from metastasis were similar to that from highgrade astroeytornas. The presence of lactate was not a reliable indicator of malignancy. Conclusion.^1H-MRS can provide information about tissue metabolism and elevate the level of medical imaging in the histologic classification and pathologic grading of brain tumors.