急性缺血性脑卒中病人DWI扫描参数优化研究

Optimization of DWI pulse sequence in patients with acute ischemic stroke

目的优化急性缺血性脑卒中(AIS)扩散加权成像(DWI)扫描参数。方法前瞻性研究纳入2016年1月—2017年6月期间共50例AIS病人,男34例,女16例,年龄47~97岁,平均年龄(66.8±11.9)岁。每例病人均采用4种参数进行DWI检查并获得4组影像,组1为对照序列,组2使用并行采集技术,组3使用并行采集技术并降低激励次数,组4使用并行采集技术,减少重复时间(TR)、回波时间(TE)并放大视野,各组扫描时间依次为177、81、23、18 s。测量4组DWI影像信噪比(SNR)、对比噪声比(CNR)、信号强度比(SIR)、病灶的表观扩散系数(ADC)值。采用单因素方差分析对4组间数据进行比较。由2位医生采用4分法评价4组DWI影像质量,并采用Kruskal-Wallis H检验进行比较。结果 4组影像的SNR、CNR差异均无统计学意义(均P>0.05)。组2的SIR最高,但1、2、3组间差异均无统计学意义(均P>0.05);组4的SIR低于其他3组(均P<0.001)。4组间ADC值差异无统计学意义(P>0.05)。组2的影像质量评分最高,但与组1间差异无统计学意义(P>0.05)。组3评分低于组1、2(均P<0.001)。组4评分<3分,低于其他3组(均P<0.001)且影响诊断。结论通过采用并行采集技术并降低激励次数(组3)的扫描方案,不仅明显缩短扫描时间,而且影像质量还能满足诊断要求,对需要紧急治疗的AIS病人有较大应用价值。

Objective To optimize the parameters of diffusion weighted imaging (DWI) in patients with acute ischemic stroke (AIS). Methods This prospective study was conducted on 50 AIS patients from January 2016 to June 2017, including 34 males and 16 females, aged 47 to 97 years, with an average age (66.8±11.9) years. Each patient underwent DWI examination using 4 parameters and obtained 4 groups of images. Group 1 was the control sequence, group 2 used parallel acquisition technology, group 3 used parallel acquisition technology and reduced excitation times, group 4 used parallel acquisition technology, reduced TR, TE time and enlarged field of vision. The scanning times were 177 s, 81 s, 23 s, and 18 s, respectively. Image signal-to-noise ratio (SNR), image contrast-to-noise ratio (CNR), image signal intensity ratio (SIR), and apparent diffusion coefficient (ADC) of lesions on the images were measured for the four groups of DWI. One-way ANOVA was used to compare the data among the four groups. The DWI image quality of 4 groups was evaluated by 2 doctors with a 4-point method and compared by Kruskal-Wallis H test. Results There was no significant difference in SNR and CNR among the 4 groups of images (P>0.05). The SIR of group 2 was the highest, but there was no significant difference among groups 1, 2, and 3 (all P>0.05). The SIR of group 4 was lower than that of the other 3 groups (all P<0.001). There was no significant difference in ADC values among the four groups (P>0.05). The image quality score of group 2 was the highest, but there was no significant difference between group 2 and group 1 (P>0.05). The score of group 3 was lower than that of group 1 and group 2 (P<0.001). The score of group 4 was less than 3 points, which was lower than that of the other three groups (P<0.001) and affected the diagnosis. Conclusion By adopting the scanning scheme of parallel acquisition technology and reducing the excitation times (group 3), the scanning time is obviously shortened while the image quality can still meet the diagnostic requirements, thus having great application value for AIS patients needing emergency treatment.