星形细胞瘤周围水肿区的磁共振弥散成像及氢质子波谱对肿瘤术前分级的综合评价

Pre-operation evaluation of edematous regions around astrocytoma by using of diffusion weighted imaging and proton MR spectroscopy

[目的]通过对星形细胞瘤周围水肿区行磁共振弥散加权成像(diffusion-weighted imaging,DWI)和氢质子磁共振波谱(proton magnetic resonance spectroscopy,1H-MRS)检查,探讨周围水肿区的DWI和1H-MRS表现在星形细胞瘤术前分级的应用价值。[方法]对经手术病理证实的28例星形细胞瘤(低级别9例,高级别19例)进行常规MRI序列、DWI和1H-MRS检查,对照分析病变的周围水肿区的表观弥散系数(apparent diffusion coefficient,ADC)值以及1H-MRS的各种代谢物比值,包括Cho/NAA、Cho/Cr、NAA/Cr,并进一步与病理结果对照。[结果]高级别星形细胞瘤周围水肿区的ADC值(12.95±1.59)×10-4mm2/s低于低级别星形细胞瘤(16.82±2.40)×10-4mm2/s,P=0.014。若周围水肿区ADC值取14.85×10-4mm2/s作为高、低级别胶质瘤分级的阈值,则敏感度为85.7%,特异度为82.1%,准确性为71.4%。高级别星形细胞瘤周围水肿区Cho/NAA值(2.13±0.74)高于低级别星形细胞瘤(1.14±0.23),P=0.02。以Cho/NAA=1.37为阈值来鉴别两者,则敏感性为96.4%,特异性为75.0%,准确性为78.6%。[结论]星形细胞瘤周围水肿区的ADC值和Cho/NAA值的测定对于肿瘤术前级别的确定十分有意义。

[Objective] To investigate clinical value of DWI and 1H-MRS in diagnosing of astrocytomas grade by performing them in the peritumoral edematous regions.[Methods] Twenty-eight patients proved of astrocytomas（9 cases of low-grade and 19 high-grade） underwent routine MR process,diffusion weighted imaging and 2D proton spectroscopic MR imaging.Apparent diffusion coefficient（ADC） and metabolic ratios including of Cho/NAA,Cho/Cr and NAA/Cr were calculated in the peritumoral edematous areas.[Results] ADC value in the peritumoral edematous areas of low-grade astrocytomas（16.82±2.40） ×10^-4 mm^2/s was significantly higher than that of high-grade ones（12.95±1.59） ×10^-4 mm^2/s,P=0.014）.A ADC threshold of 14.85×10^-4 mm^2/s in peritumoral area provided for sensitivity by 85.7%,specificity by 82.1% as well as accuracy by 71.4% in differentiation high-grade from low-grade astrocytomas.Significantly higher ratio of Cho/NAA was found in the peritumoral edematous area（2.13±0.74,P=0.02） of high grade gliomas compared with low grade ones（1.14±0.23）.A threshold of Cho/NAA equal to 1.37 in peritumoral area was provided for differentiation high-grade from low-grade astrocytomas,and then sensitivity,specificity and accuracy were by 96.4%,75.0% and 78.6% respectively.[Conclusion] ADC values and Cho/NAA quantification in the peritumoral edematous areas are useful complementary methods in diagnosing of astrocytomas grade.