常规MR和弥散加权成像对原发性中枢神经系统淋巴瘤和胶质母细胞瘤的鉴别诊断价值

Value of conventional MR and diffusion weighted imaging in differentiating primary central nervous system lymphoma and glioblastoma

目的探讨常规MR和弥散加权成像（DWI）在原发性中枢神经系统淋巴瘤（PCNSL）和胶质母细胞瘤（GBM）鉴别诊断中的价值。方法回顾性分析27例GBM和22例PCNSL病例的常规MR图像，分析其信号特点。测量肿瘤平均表观弥散系数（meanADC，ADC。）。同时测量对侧正常脑白质区的ADC值，计算肿瘤校正ADC值（correctedADC，ADCc=ADC㈣《镕／ADCNⅧ自镕）。两组问常规MR信号特点采用卡方检验比较，ADC。和ADC。值采用t检验比较。采用受试者工作特性曲线（ROC）分析ADCM和ADCC、值对GBM和PCNSL的鉴别诊断价值。结果GBM和PCNSL组在TIWI（P=0．06）和T2WI（P=0．86）上的信号特点比较差异无统计学意义，在强化均匀性方面比较差异有统计学意义（P〈0．01）。GBM组的ADCM和ADCC．值均明显高于PCNSL组[ADCM：（O．97±0．17）×10^-3mm^2／s比（0．69±0．11）×10^-3mm^2／s，P〈0．01]；[ADCC：（1．28±0．21）比（0．92±0．13），P〈0．01]。ROC曲线分析结果提示，以ADCC值≤0．85×10^-3mm^2／s为阈值，可获得最优的诊断效能（AUC：0．911，敏感度：95．5％，特异度：81．5％）。以ADC，值≤1.09为阈值，可获得最优的诊断效能（AUC：0．936，敏感度：95．5％，特异度：85．2％）。结论DWI和ADC值可辅助GBM和PCNSL的鉴别诊断，为常规MR提供补充信息。

Objective To evaluate the role of conventional magnetic resonance （MR） imaging and diflhsion weighted imaging （DWI） in differentiating primary central nervous system lymphoma （PCNSL） and glioblastoma （GBM）. Methods Conventional MR and DWI images of 27 patients with GBM and 22 patients with PCNSL were retrospectively analyzed. The mean apparent diffusion coefficient （ADC） of the tumor and contralateral white matter were measured, and the corrected ADC value was calculated （ADCC = ADC tumor/ADC contralateral white matter）. Visual signal characteristics on T1WI and T2WI between PCNSL group and GBM group were compared by chi square test, the ADCM and ADCC value between the two groups were compared by t test. Receiver operating characteristic （ROC） curve were used to determine the diagnostic value of ADCM and ADCC in differentiating PCNSL from GBM. Results There was statistically significant difference in the enhancement homogeneity between the PCNSL group and the GBM group （P〈0.01）, while there were no statistically significant differences in the signal characteristic on T1WI （P = 0.06） and T2WI （P = 0.86） between the PCNSL group and the GBM group. GBM showed significantly higher ADCM and ADCC values than PCNSL group [（0.97±0.17）×10^-3 mm^2/s vs.（0.69±0.11） ×10^-3 mm^2/s, （1.28±0.21 ） vs.（0.92±0.13）; P〈0.01 ]. ROC curve indicated that setting ADCM 〈0.85 ×10^-3 mm^2/s as threshold value, optimal diagnostic ability could be obtained （AUC： 0.911; sensitivity： 95.5%;specificity： 81.5%）; setting ADCC 〈1.09 as threshold value, optimal diagnostic ability could be obtained （AUC： 0.936; sensitivity： 95.5%; specificity： 85.2%）. Conclusion DWI could aid in the differentiating diagnosis between PCNSL and GBM, which provides supplementary information for conventional MR imaging.