~1H-MRS对颅内淋巴瘤与肿瘤样脱髓鞘病变的鉴别诊断价值

Differential Diagnosis of Intracranial Lymphoma from Tumor-like Demyelinating Lesions by Using ~1H-MRS

目的探讨1H-磁共振波谱(MRS)对颅内淋巴瘤与肿瘤样脱髓鞘病变(TDLs)的诊断价值,为临床诊断提供依据。资料与方法收集经病理证实的33例颅内淋巴瘤、经病理或临床证实的18例TDLs患者的影像学资料,分析使用单体素点分辨序列扫描MRS(TE 144 ms),计算胆碱(Cho)/肌酸(Cr)和Cho/N-乙酰天门冬氨酸(NAA)比值,目视估测脂质-乳酸(Lip-Lac)峰与Cr峰高度比分为5个等级。比较颅内淋巴瘤与TDLs的MRS分析结果,评价常规MRI和增加1H-MRS后对两者鉴别阈值的变化。结果 33例颅内淋巴瘤和18例TDLs的Cho/Cr、Cho/NAA比值及Lip-Lac峰等级差异有统计学意义(P<0.001)。Cho/Cr>2.56、Cho/NAA>1.71及Lip-Lac峰等级>3级时提示为颅内淋巴瘤。与TDLs相比,不典型颅内淋巴瘤的Cho/Cr、Cho/NAA比值及Lip-Lac峰等级均较高。在常规MRI难以鉴别的28例中补充Cho/NAA比值,相对于常规MRI成像ROC面积由0.827增加到0.870。结论1H-MRS对鉴别诊断颅内淋巴瘤与TDLs有重要价值,Cho/Cr比值>2.56、Cho/NAA比值>1.71和Lip-Lac峰>3级提示为颅内淋巴瘤而非TDLs,当常规MRI难以鉴别时,增加Cho/NAA比值是常规MRI鉴别诊断的有益补充。

Purpose To investigate H-MRS in differentiating intracranial lymphoma from tumor-like demyelinating lesions. Materials and Methods Thirty-three cases of intracranial lymphoma confirmed by pathology and 18 cases of tumor-like demyelinating lesions confirmed by pathology or clinic were recruited in this study. Imaging data including single-voxel （TE=144 ms） H-MRS was retrospective analyzed. The Cho/Cr and Cho/NAA area ratios were calculated. The lipid and lactate peak was visually categorized into 5 grades based on the ratio of Lip-Lac peak to the height of the Cr peak. H-MRS findings of the intracranial lymphoma and the tumor-like demyelinating lesions were compared. The differentiation of the two diseases diagnosed by t H-MRS and conventional MR were evaluated by use of receiver operating characteristic curves. Results There were significant difference of Cho/Cr, Cho/NAA ratio and Lip-Lac peak level between the intracranial lymphoma and tumor-like demyelinating lesions （P〈0.001）. It was more likely to be intracranial lymphoma when Cho/Cr ratio was〉2.56, Cho/NAA ratio was〉l.71, and Lip-Lac peak grade was〉3. Cho/Cr, Cho/NAA ratio and Lip-Lac peak grade were found higher in atypical intracranial lymphomas when compared with those of tumor- like demyelinating lesions. The area under the receiver operating characteristic curve of conventional MR was increased from 0.827 to 0.870 when Cho/NAA ratio was added for analysis in the 28 uncertain cases. Conclusion H-MRS has great clinical significance for differentiating intracranial lymphoma from tumor-like demyelinating lesions. The values of Cho/Cr ratio〉2.56, Cho/NAA ratio〉1.71 and Lip-Lac grade 〉3 suggest intracranial lymphoma rather than TDLs. When the conventional MR imaging features can not do the differentiation, Cho/NAA ratio is a useful complement.