磁共振扩散加权成像技术在颅内囊性病变鉴别诊断中的应用

The application of diffusion-weighted MR imaging in the differential diagnosis of intracranial cystic diseases

目的探讨磁共振扩散加权成像(DWI)技术对颅内囊性病变中表皮样囊肿、蛛网膜囊肿、脑脓肿及囊性坏死性脑肿瘤(单发囊性转移瘤、神经上皮肿瘤)的鉴别诊断价值。方法对2004年5月-2006年5月行神经外科手术治疗并经病理证实的50例颅内囊性病变患者的磁共振扩散加权成像资料进行回顾性分析,其中表皮样囊肿10例、蛛网膜囊肿10例、脑脓肿10例、单发囊性转移瘤8例及神经上皮肿瘤12例,均进行常规MRI平扫及DWI检查,生成DWI图及表观扩散系数(ADC)图,观察囊变区信号特征并测量该区的表观扩散系数值。结果(1)表皮样囊肿在扩散加权成像显示为高信号,其表观扩散系数图显示为低或稍低信号,表观扩散系数测量值为(0.92±0.12)×10-3mm2/s,蛛网膜囊肿扩散加权成像显示为低信号,表观扩散系数图呈高信号,测量值为(3.09±0.21)×10-3mm2/s;两组表观扩散系数测量值差异有统计学意义(t=22.278,P=0.000)。(2)脑脓肿之囊变区于扩散加权成像显示为高信号,表观扩散系数图呈低及等信号,表观扩散系数测量值为(0.52±0.08)×10-3mm2/s;单发囊性转移瘤和神经上皮肿瘤之囊变区在扩散加权成像上显示为低信号,表观扩散系数图显示为高信号,表观扩散系数测量值为(2.35±0.41)×10-3mm2/s,与脑脓肿组相比差异有统计学意义(t=13.939,P=0.000)。结论不同颅内囊性病变在磁共振扩散加权成像上的表现特点及病灶囊变区表观扩散系数测量值的变化,具有诊断与鉴别诊断价值。

Objective To evaluate the differential diagnosis value of diffusion-weighted magnetic resonance （MR） imaging （DWI） in intracranial cystic diseases （epidermoid cyst, arachnoid cyst, brain abscess） and necrotic cystic brain tumors （single cystic metastatic neoplasm, neuroepithelioma）. Methods DWI data were analysed retrospectively in 50 patients with intracranial cystic disease （10 cases with epidermoid cyst, 10 cases with arachnoid cyst, 10 cases with brain abscess, 8 cases with single cystic metastatic neoplasm and 12 cases with neuroepithelioma） who received operative treatment and were verified by histopathological examination from May, 2004 to May, 2006. Conventional MR imaging and DWI were performed in all patients. Signal features and average diffusion coefficient （ADC） value in cystic lesion region were obtained from DWI map and ADC map. Results 1） Epidermoid cyst presented hyperintense signal on DWI, hypointense or slightly hypointense signal on ADC map, the ADC value was （0.92 ± 0.12） × 10^-3 mm^2/s; arachnoid cyst showed hypointense signal on DWI map,hyperintense signal on ADC map, the ADC value was （3.09±0.21）× 10^-3 mm^2/s, there was significant difference in ADC value between epidermoid cyst and arachnoid cyst （t = 22.278, P= 0.000）. 2） The cystic lesion area of brain abscess appeared hyperintense signal on DWI map, hypointense or isointense signal on ADC map, the ADC value was （0.52± 0.08） ×10^-3 mm^2/s; the cystic lesion area of single cystic metastatic neoplasm and neuroepithelioma showed hypointense signal on DWI map, hyperintense signal on ADC map, the both ADC values were all （2.35 ±0.41） × 10^-3 mm^2/s; there was significant difference in ADC value between brain abscess and necrotic cystic brain tumors （t= 13.939, P=0.000）. Conclusion The DWI features in different intracranial cystic diseases and ADC value changes in cystic lesion area are useful for the diagnosis and differential diagnosis of intracranial cystic diseases.