液体衰减反转恢复预脉冲弥散成像检测短暂性脑缺血发作急性缺血病灶的限度

Pitfall in the detection of acute lesions of transient ischemic attack with fluid-inversion prepared diffusion weighted imaging

目的探讨液体衰减反转恢复预脉冲弥散成像(FLIPD)技术对急性脑缺血灶检测能力的限度。方法2012年1月至2014年3月间49例[男33例,女16例,年龄(55.6±12.3)岁]临床诊断为短暂性脑缺血发作(TIA)的患者,在发病3 d内进行了头颅常规弥散加权成像(DWI)和FLIPD检查。比较2种技术对TIA后脑内急性缺血灶的检出能力,并比较急性缺血灶在常规DWI和FLIPD中的相对信号强度(rSI)和表观弥散系数(ADC)。采用Kappa检验和两样本t检验进行数据分析。结果常规DWI检出21例患者有颅内急性缺血灶,共87个;而FLIPD检出19例患者的54个颅内急性缺血灶(Kappa=0.916,P<0.05)。FLIPD中缺血灶的rSI明显低于常规DWI中的相应值(1.37±0.22 与 1.57±0.26;t=6.647,P<0.001),ADC 略低于常规 DWI 中相应值[(0.54±0.10)×10^-3与(0.57±0.13)10^-3mm^2/s;t=2.120,P<0.05]。 FLIPD 漏检的病灶位于白质(n=18),小脑和脑干(n=8),皮质区5=7)。结论轻微的弥散异常在FLIPD中会被漏诊,该法不适合急性缺血病灶的检测。FLIPD技术仍有待改进。

Objective To explore the limits of fluid-inversion prepared diffusion weighted imaging (FLIPD) in detection of acute cerebral ischemic lesions. Methods From January 2012 to March 2014, forty-nine patients (33 males, 16 females, age (55.6± 12.3) years) clinically diagnosed as transient ischemic attack (TIA) were included. Patients underwent brain MRI (conventional diffusion weighted imaging (DWI) and FLIPD) within 3 d after the onset of TIA. The detection ability of MRI with the two sequences was compared, and the relative signal intensity (rSI) and apparent diffusion coefficient (ADC) of acute ischemic lesions based on two sequences were compared. Kappa test and two-sample t test were used to analyze the data. Results A total of 87 acute ischemic lesions were detected in 21 patients by conventional DWI, and 54 were detected in 19 patients by FLIPD (Kappa=0.916, P<0.05). The rSI of ischemic lesions on FLIPD was significantly lower than that on conventional DWI (1.37±0.22 vs 1.57±0.26;t=6.647, P< 0. 001). The ADC value of ischemic lesions on FLIPD was slightly lower than that on conventional DWI:(0.54 ±0.10)×10^-3mm^2/s vs (0.57±0.13×10^-3mm^2/s(t=2.120,P<0.05].The missed lesions on FLIPD were located in the white matter (n=18), cerebellum and brainstem (n=8), and the cortex (n=7). Conclusions A slight diffuse abnormality may be missed on FLIPD, so this method is not suitable for the detection of acute ischemic lesions. FLIPD technology still needs improvement.