TIA患者脑动态CT峰值时间灌注成像的初步研究

Preliminary Study of Cases of TIA with CT Time - to - Peak Perfusion Mapping

目的:探讨脑动态CT峰值时间（TTP）灌注成像对短暂性脑局部缺血发作（TIA）的诊断价值。材料和方法:对17例临床诊断为TIA的患者进行脑动态CT扫描TTP灌注成像检查。感兴趣区层厚10mm,扫描矩阵512×512,曝光电压和功率与常规扫描相同。动态CT检查为在启动高压注射器经肘静脉快速注入对比剂的同时对感兴趣层面进行连续快速扫描。曝光时间为1s,连续扫描40s,共40层。碘对比剂为300mg碘海醇,流量为8ml/s,总量为40ml。CT检查结束后,用自编软件进行动态增强CT数据处理。用手工画线方式将脑实质与颅骨、皮下组织、脑室和图像背景分割,最后仅留下脑实质的彩色TTP灌注图像。结果:17例常规CT检查（包括增强检查）和12例常规MR检查均未发现脑内有与TIA发作临床表现相符合的新鲜病灶。脑动态CT扫描TTP灌注成像显示脑内有与TIA发作临床表现相符合的病灶14例（82.35％）。其余3例脑TTP灌注成像未见异常。结论:虽然动态CT峰值时间脑灌注成像只能进行单一层面的检查,但其方法简单、易行,可显示常规CT和MR无法发现的早期脑缺血区的血流异常,对TIA的研究具有重要临床实用价值。该方法优于CBF和CBV灌注成像。

Purpose:To evaluate the diagnostic value of time - to - peak perfusion mapping using dynamic CT with a personal computer for transient ischemic attack(TIA) . Materials and Methods: First - pass, single -section time - to - peak perfusion mapping using dynamic CT was performed in 17 patients who presented with TIA. Single - section perfusion CT scans (thickness, 10 mm; image matrix, 512×512) were obtained immediately after the nonenhanced CT study in a interested section. 40 mL nonionic contrast agent was administered with a constant flow rate of 8 mL/ s via the antecubital vein by using a power injector.As soon as the injection started, raw data were acquired by rotating the X - ray tube continuously while keeping the table stationary.Each 360° rotation took 1 second, and the total acquisition time was 40 seconds. From this data set, a series of images with a time interval of 1 second was reconstructed, corresponding to 40 images. The perfusion raw data set was also processed off - line on a personal computer using a software package which was made by ourselves. Images were manually segmented to separate brain parenchyma from the skull, ventricles, and background. Results: Diagnostic time - to - peak maps were generated in 17 cases of TIA. The time - to - peak map showed perfusion deficits in 14 of 17 patients (82.4% ) . The normal time - to - peak mapping findings were showed in 3 cases of TIA. The time - to -peak perfusion mapping contributed to display the abnormal area of ischemia, which was showed as normal imaging appearances in routine CT and MR images.Conclusion: Although limited to a single section, time - to - peak perfusion mapping using dynamic CT with a personal computer is a simple and accessible technique for delineating the regional hemodynamic abnormality in cases of TIA which was viewed as normal imaging findings in routine CT and MR examination. The method is easy to apply and yields diagnostic results within a few minutes.It may guide treatment decisions. The TTP perfusion mapping is more suitable to examine the patients with TIA than CBF and CBV perfusion mapping.