DW、T_2WEPI序列在诊断出血性和非出血性脑梗死中的作用

Role of diffusion- and T_2-weighted EPI in distinguishing between hemorrhagic and nonhemorrhagic stroke

目的:了解DW和T2W平面回波磁共振成像在诊断急性出血性脑梗死以及区别出血性和非出血性脑梗死中的作用。方法:应用单次激发三向同性DW/T2WEPI、T2WFSE和常规T1WSE序列对36例病人进行MR扫描,其中有18例非出血性梗死的病人,18例出血性梗死的病人。测量感兴趣区(ROI)及对侧相应解剖部位的表面弥散系数(ADC)值及T2W信号强度值,由此计算相对ADC(rADC)、T2WEPI和FSET2W相对信号强度比(rSIR)。结果:(1)急性出血性和非出血性脑梗死病灶都表现出ADC的降低;(2)急性出血性脑梗死在T2WEPI上呈低信号或高低混杂信号,而急性非出血性脑梗死在T2WEPI和FSET2W上表现正常或稍高信号;(3)急性期及亚急性期非出血性脑梗死都表现出DWI的高信号或不均匀高信号,发病4h之内的出血性病灶表现为DWI的高信号,而发病6～48h之内的出血性病灶DWI表现为低信号或高低混杂信号;(4)出血性脑梗死中病灶处ADC的降低会比非出血性脑梗死持续得更久。结论:结合三向同性DWI和T2WEPIMR成像能够比常规MRI更准确地检测和鉴别出急性出血性和非出血性脑梗死。

Aim: To determine if diffusion- and T 2-weighted echo-planar magnetic resonance imaging (EPI) can be used to detect acute hemorrhagic stroke and to differentiate hemorrhagic from nonhemorrhagic stroke. Methods: 18 patients with hemorrhagic strokes and 18 patients with nonhemorrhagic strokes were examined. Conventional MRI and single-shot isotropic diffusion-weighted (DW) and T 2-weighted (T 2W) EPI were performed. Apparent diffusion coefficient (ADC), the ratios of ADC and of signal intensity on T 2-weighted EPI and FSE T 2-weighted MR images in lesions to those in contralateral control areas were calculated. Results: Decreased ADC was shown in lesions of acute hemorrhagic and nonhemorrhagic stroke. Hypointense or mixed hypo- and hyperintense areas were seen on T 2W EPI images in patients with acute hemorrhagic stroke, in contrast to normal to slightly increased signal intensity on T 2W EPI and FSE T 2W images in those with acute nonhemorrhagic stroke. Hyperintensity or heterogeneous hyperintensity were seen on DW images in patients with acute and subacute nonhemorrhagic stroke. Hyperintensity were seen on DW images which were initially obtained 4 hours after onset in patients with hemorrhagic stroke, while hypointensity or mixed hypo- and hyperintensity were seen on DW images obtained 6 to 48 h after onset in those with hemorrhagic stroke. Decreased ADC tended to persist longer in hemorrhagic stroke lesions than in nonhemorrhagic stroke lesions. Conclusion: It can be more sensitively and accurately than conventional MRI that isotropic diffusion- and T 2-weighted EPI detect and distinguish between acute hemorrhagic and nonhemorrhagic stroke.