脑实质结核与脑转移瘤的MRI鉴别及多b值DWI量化分析

Value of MRI and Quantitative Analysis of Multi-b-value DWI in Differentiating Brain Parenchymal Tuberculosis from Brain Metastases

目的:分析脑实质结核的MRI特点,探讨多b值弥散加权成像(DWI)对脑实质结核与脑转移瘤鉴别诊断的应用价值。方法:对28例脑实质结核和31例脑转移瘤患者行MRI检查和多b值DWI成像,分析两者的MRI表现,测量实性强化病灶及环形强化病灶的强化环壁、中央坏死的各类表观扩散系数(apparent diffusion coefficient,ADC)值,包括ADC_(10b)、ADC_(high)及ADC_(perf)值,采用两样本t检验。结果:脑实质结核337个病灶,实性均匀强化病灶102个,69.6%≤3.0mm,25.5%在3.0~10.0mm之间;环形强化病灶235个,环壁厚薄均匀光整,32.4%在3.5~5.0mm之间,45.5%在5.0~10.0mm之间,22.1%≥10.0mm。脑转移瘤285个,实性欠均匀强化病灶74个,27.0%≤3.0mm,73.0%>3.0mm;环形强化病灶211个,环壁凹凸不平,84.8%>5.0mm。脑实质结核中实性强化结节、强化环壁的ADC_(high)值分别为(0.240±0.038)×10^(-3)mm^2/s、(0.249±0.039)×10^(-3)mm^2/s,均高于脑转移瘤,脑实质结核环形强化病灶干酪实性中心区的ADC_(high)值为(0.251±0.056)×10^(-3)mm^2/s,低于脑转移瘤的中心坏死区。环形强化病灶中环壁的ADC_(10b)及ADC_(high)值分别以0.088×10^(-3)mm^2/s和0.241×10^(-3)mm^2/s为界,鉴别脑实质结核与脑转移瘤的灵敏度分别为83.9%、58.9%,特异度分别为72.5%、100%。结论:结合病灶大小、MRI强化方式及ADC_(high)值与ADC_(10b)值的测量有利于脑实质结核和脑转移瘤的鉴别诊断。

Purpose： To study the MRI findings of brain parenchymal tuberculosis, and to explore the valve of multi-b-value diffusion weighted imaging （multi-b-DWI） in differentiating parenchymal tuberculosis from brain metastases. Methods： The conventional MRI and multi-b-DWI were performed in 59 cases （28 cases with parenchymal tuberculosis, and 31 cases with brain metastases）, their MRI findings were retrospectively summarized. Apparent diffusion coefficient （ADC） values, including ADC10b, ADChigh and ADCperf, were measured in the solid enhanced nodules, the rim and central of ring-like enhanced lesions. All the data were analyzed by t test. Results： There were 337 brain parenchymal tuberculosis lesions. Of them, 102 lesions were evenly enhanced nodules, 69.6% of the lesions were less than 3.0mm, 25.5% of the lesions were between 3.0mm to 1.0cm; 235 lesions showed ring-like contrast enhancement, 32.4% of the lesions were between 3.5ram to 5.0mm, 45.5% of the lesions were between 5.0mm to 1.0cm, 22.1% of the lesions were more than 1.0cm. There were 285 brain metastases lesions. Of them, 102 lesions were heterogeneously enhanced nodules, 27.0% of the lesions were less than 3.0ram, 73.0% of the lesions were more than 3.0mm; 211 lesions showed unevenly ring- like enhancement, 84.8% of the lesions were more than 5.0ram. The ADCh^gh of the solid nodules and ring wall of parenchymal tuberculosis were （0.24±0.038）×10^3mm^2/s, （0.249±0.039）× 10^-3mm^-3/s, they were higher than that of the brain metastases. The ADChigh of caseous solid center of ring enhancing lesions in parenchymal tuberculosis was （0.251±0.056）× 10^-3mm^2/s, it was lower than that of the necrosis center of brain metastases. When ADC100 and ADChigh of the enhancing ring wall were set as 0.088× 10^3mm^2/s and 0.241× 10^3mm^2/s, the sensitivity in differentiating these two diseases were 83.9% and 58.9%, the specificity were 72.5% and 100% respectively. Conclusion： Combination of the lesion size, MRI enhanced features and ADC values are helpful in differential diagnosis of brain parenchymal tuberculosis and brain metastases.