慢性脑缺血的多模态CT成像及临床高危因素分析

目的：运用CT灌注（CTP）及CT血管造影（CTA）一站式低剂量多模态CT评价慢性脑缺血（CCH）患者脑组织血流灌注改变，并分析CCH的临床高危因素。方法：应用640层容积CT对266例临床拟诊CCH的患者进行全脑CTP检查，经后处理得到各个供血区的脑血流量（CBF）、脑血容量（CBV）、达峰时间（TTP）和延迟时间（DT）等灌注参数以及CTA图像，以患侧/对侧算得相对比值（rCBF、rCBV、rTTP及rDT值），并分析各患者脑血管的狭窄情况。采用配对t检验分析患侧与健侧大脑半球各个灌注参数的差异，成组t检验分析灌注不足组与灌注正常组之间各个灌注参数相对值的差异，秩合检验分析灌注不足组与灌注正常组患者供血血管狭窄程度之间的差异；并对灌注不足的相关临床高危因素进行logistic回归分析。结果：①灌注不足组184例，CTP示两侧大脑半球灌注不对称，患侧CBF、CBV低于对侧，而TTP、DT高于对侧，各灌注参数差异有统计学意义（P＜0.01）。其中前循环灌注不足98例，后循环灌注不足61例，多供血区灌注不足25例；②灌注不足组rCBF、rCBV相对值低于灌注正常组，而rTTP、rDT高于灌注正常组，差异均有统计学意义（t=-3.943、-3.862、2.790、4.558，P＜0.01）；③184例灌注不足组患者中，血管评估显示轻度狭窄24例，中度狭窄47例，重度狭窄65例以及闭塞48例；82例灌注正常组患者中，轻度狭窄54例，中度狭窄21例，重度狭窄5例及闭塞2例，2组血管狭窄程度差异有统计学意义（P＜0.01）；④在灌注不足组患者与灌注正常组之间糖尿病、高血脂、吸烟、饮酒的病例数差异有统计学意义（P＜0.05），多因素logistic回归分析显示吸烟和高血脂是脑灌注不足的危险因素。结论：多模态CT不仅可以显示脑血管狭窄程度，而且还可以直观和定量反映CCH患者脑组织血流灌注情况，为CCH的诊断和防治提供客观的影像学依据。

An analysis of multi-modality CT imaging and high-risk clinical factors of chronic cerebral hypoperfusion

Objective: To evaluate the microcirculation and hemodynamic changes in patients with chronic cerebral hypoperfusion (CCH) via one-stop low-dose multi-modality CT including CT perfusion (CTP) and CT angiography (CTA), and to analyze the clinical risk factors. Methods: Whole-brain CTP imaging was performed on 266 patients with suspected diagnosis of CCH using 640 multi-slice CT. Following the post-processing, cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), delay time (DT) and Four-dimensional CTA images were acquired. The relative perfusion parameters (rCBF, rCBV, rTTP and rDT) were calculated and the stenosis degree of brain arteries was evaluated. The perfusion parameter differences between two hemispheres were analyzed by comparative t-test; the perfusion parameter differences between hypoperfusion group and normal perfusion group were analyzed by independent t-test; the difference on stenosis degree of supplying blood vessel between hypoperfusion group and normal perfusion group were analyzed by the rank sum test and the clinical risk factors were analyzed by Chi-square test and logistic regression. Results: ①In the hypoperfusion group, 184 patients demonstrated perfusion asymmetry on both hemispheres. CBF and CBV of the affected side were lower than that of contralateral side, while TTP and DT were prolonged, the differences of all perfusion parameters between two sides had statistical significance (P<0.01). Among these cases, 98 cases had anterior circulation insufficient, 61 cases had posterior circulation insufficient, and 25 cases had multi-region circulation insufficient. ②rCBF and rCBV of the hypoperfusion group were lower than that of the normal perfusion group, while rTTP and rDT were higher than the latter. The perfusion parameters of CCH group were 0.75±0.44, 0.76± 0.56, 1.16±0.22, and 1.56±0.34; the perfusion parameters of normal perfusion group were 0.93±0.51, 0.92±0.09, 1.03±0.07, and 1.06±0.17. The difference between two groups had statistical significance (t=-3.943, -3.862, 2.790, 4.558, P<0.01). ③In 184 cases of hypoperfusion, 24 cases were mild stenosis, 47 cases moderate stenosis, 65 cases severe stenosis and 48 cases occlusion on CTA. Among 82 normal perfusion cases, 54 cases were mild stenosis, 21 cases moderate stenosis, 5 cases severe stenosis and 2 cases occlusion on CTA. The differences in artery stenosis between two groups had statistical significance (P<0.01). ④The incidence of diabetes, hyperlipidemia, and smoke was statistically different between hypoperfusion group and NCCH group (P<0.05). Confirmed by multi-factor logistic regression analysis, smoke and hyperlipidemia were high risk factors of hypoperfusion. Conclusion: Multi-modality CT imaging can not only demonstrate the degree of cerebral artery stenosis, but also directly and quantitatively reflect the microcirculation perfusion of brain tissue in CCH patients, and provide an objective imaging basis for the diagnosis and prevention of CCH.