高扩散敏感系数扩散加权像异常高信号疾病的鉴别诊断

The differential diagnosis of hyperintensity lesions on high diffusion sensitive gradient diffusion-weighted imaging

目的 总结在扩散加权像 (DWI)上表现为异常高信号的疾病种类及其MRI表现 ,探讨高扩散敏感系数 (高b值 )DWI上异常高信号征象的鉴别诊断与相关的生物物理学机制。方法 分析临床高度怀疑脑缺血性中风 ,并且在高b值DWI上发现异常高信号病灶的病人 90例 ,根据发病距检查时间分组 :A组 (1 5～ 6 0h) 13例 ,B组 (7h至 8d) 77例。总结MRI的表现 ,并对病灶进行表观扩散系数 (ADC)及各向异性变异系数 (CV)的计算。结果 急性期脑缺血、颅内出血与血肿、脑脓肿、脑膜瘤、多发性硬化 (MS)的急性发作期等均可在高b值DWI上表现为异常信号。超急性期脑缺血ADC值下降为 (5 87± 1 0 2 )× 10 -4mm2 /s,而MS病例中ADC值轻微升高达 (8 0 8± 1 15 )× 10 -4mm2 /s(P <0 0 5 ) ;脑缺血区的各向异性CV升高 ,与正常对照组的比值为 9 2 1(2 36～ 36 0 5 ) ,(P <0 0 5 ) ,而MS的CV明显下降 ,与正常对照的比值为 0 4 1(0 2 1～ 1 4 5 ) (P <0 0 5 )。超急性、急性期脑缺血与活动性MS均在DWI上与T2 WI上表现相似 ,ADC比率间无显著性差异 (P >0 0 5 ) ,而CV比率间存在显著性差异 (P <0 0 5 )。结论 应用DWI诊断疾病时 ,应常规计算ADC值 ,并结合病史进行综合诊断。针对鉴别困难的病例 。

Objective To summarized the diseases which were demonstrated as hyperintensity lesions on high diffusion sensitive gradien(high b value) diffusion weighted imaging(DWI) To investigate the differential diagnosis of the diseases and to discuss the corresponding biophysics mechanism Methods 90 cases were studied, which were clinically highly suspected of brain ischemic stroke onset and in which hyperintensity lesions were demonstrated on DWI The patients were divided to 2 groups according to the time between the onset and the MR examination:group A(1 5-6 0 h)with 13cases, group B(7 h to 8 d)with 77cases The appearances of the lesions on conventional MRI, ADC values and anistropy(CV )of the lesions were studied Results hyperintensity lesions on high b value DWI were demonstrated in following diseases: acute ischmia, hematoma, abcesses, mengioma, mutiple sclerosis(MS) The ADC value was decreased to(5 87±1 02)(10 -4 mm 2/s in superacute cerebral ischemia, while the ADC value increased to (8 08±1 15)×10 -4 mm 2/s in active MS The CV in cerebral ischemia lesions was higher than the control group( P <0 05)with CV ratio(CVR) of 9 21(2 36～36 05),While CV in MS was lower than the control group with the CVR of 0 41(0 21～1 45)( P <0 05) superacute, acute cerebral ischemia and active MS had similar appearances on DWI Statistical significant was found in CVR but not in ADCR among them( P <0 05) Conclusion ADC value should be calculated routinely as DWI was used to make diagnosis, and the diagnosis should be made with the comprehensive consideration of the clinical history CV value of the lesion has great value in the confusing diseases