扩散张量成像在脑环形强化病变中的鉴别诊断价值

Study of diffusion tensor imaging in brain ringlike-enhanced lesions

目的评价 MR 扩散张量成像(DTI)在环形强化病变鉴别诊断中的应用价值。方法搜集经病理或临床证实的脑脓肿9例、胶质母细胞瘤12例、单发转移瘤10例,行常规 MR 平扫、增强扫描及 DTI 检查。构建表观扩散系数(ADC)图和各向异性分数(FA)图,并测量病灶中心及周围水肿区的 ADC、FA 值。结果脓肿腔 DTI 表现为高信号,水肿区呈等或低信号;胶质母细胞瘤和转移瘤中心坏死区呈低信号,水肿区呈等信号或稍低信号。在 ADC 图上,脓肿呈低信号,平均 ADC 值为(0.66±0.07)×10^(-3)mm^2/s,水肿区呈高信号;胶质母细胞瘤和转移瘤均呈高信号,平均 ADC 分别为(2.50±0.11)×10^(-3)mm^2/s、(2.37±0.52)×10^(-3)mm^2/s,其周围水肿区亦呈高信号。脓肿与胶质母细胞瘤、转移瘤坏死区 ADC 值差异有统计学意义(F=108.80,P<0.05)。在 FA 图上,病灶坏死区与水肿均表现为低信号,脓肿与胶质母细胞瘤、转移瘤坏死区 FA 值分别为0.15±0.04、0.07±0.01、0.06±0.01,差异有统计学意义(F=34.52,P=0.000);水肿区3组间 FA 值分别为0.15±0.01、0.20±0.05、0.13±0.04,差异有统计学意义(F=8.82,P=0.001)。结论在 DTI 上,脓肿表现为较特异的高信号,ADC 值较低,有助于和囊变、坏死性肿瘤鉴别。

Objective To evaluate diagnostic value of diffusion tensor imaging （DTI） in ringlikeenhanced lesions. Methods Nine abscesses, 12 glioblastomas, 10 metastases confirmed clinically or pathologically underwent conventional MRI and DTI. Average diffusion coefficient （ADC） value, fractional anisotropy （FA） value and maps were calculated in the central portion and peripheral edema of the lesions. Results On DTI, the abscesses displayed as hyperintense signal with hypointense or isointense signal of edema; but glioblastomas and metastases all showed as hypointense signal with isointense or hypointense signal of edema. On ADC map, the abscesses showed as hypointense signal, the mean ADC value was （0.66±0.07） × 10^-3mm^2/s, The mean ADC value were （2.50±0.11） × 10^-3mm^2/s and （2.37 ± 0. 52） × 10^-3 mm^2/s for the glioblastomas and metastases, respectively, all demonstrated as hyperintense signal with slightly hyperintense signal of edema. The difference between abscess and necrotic tumors was statistically significant （ F = 108.80 ,P 〈0.05 ）. The FA value were 0. 15 ±0. 04, 0.07 ±0. 01 and 0. 06 ± 0.01 for the abscess, glioblastoma and metastasis, respectively. The peri-edema was all depicted as hypointense signal on FA map. The difference between abscess and necrotic tumors was statistically significant（ F = 34.52, P = 0. 000 ）. The difference in edema among the three groups were also obviously significant （F = 8.82,P = 0. 001 ）. Conclusion DTI can demonstrate abscess as hyperintense signal with low ADC value. It is helpful to differentiate abscess from glioblastoma and metastasis.