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目的 探讨极低剂量脑CT灌注成像(CTPI)联合全模型迭代重组(IMR)技术临床应用的可行性.方法 收集因临床怀疑缺血性脑梗死需行脑CTPI且3 d内行MRI检查的95 例患者纳入研究,A组45 例、B组50 例,分别采用80 kV-30 mAs、80 kV-10 mAs扫描,均采用IMR2重组,并选取其脑灌注正常各45、50 侧.比较2组图像质量主观评分、有效剂量(ED)和阿尔伯塔脑卒中计划早期CT评分层面2(ASPECT2)水平灰白质的CT值、图像噪声(SD)、信噪比(SNR)、对比噪声比(CNR)以及灌注参数值和不同大小梗死灶的显示率.结果 (1)A、B 组ED分别为0.500、0.167 mSv;(2)A组主观评分好,B组中等且出现同心圆和黑洞伪影;2组灰白质CT值及灰质SNR差异无统计学意义(P＞0.05);灰白质SD值B组均大于A组,白质SNR及CNR值B组均小于A组(P＜0.05);(3)A、B组灰白质CBV、TTP及灰质MTT差异均无统计学意义(P＞0.05);2组灰白质CBF及白质MTT差异均有统计学意义(P＜0.05);(4)A、B组对腔隙性梗死灶显示率分别为4.44%、4.00%,局灶性及大面积梗死灶显示率均为100%.结论 IMR联合10 mAs脑CTPI虽然图像质量较差,但辐射剂量极低,能诊断局灶性和大面积脑梗死,对辐射损伤风险大及需多次动态随访患者具有一定的临床应用价值.,Objective To investigate the feasibility of ultra-low-dose CT perfusion imaging (CTPI) combined with iterative model reconstruction (IMR) in the brain. Methods 95 patients with clinical suspicion of ischemic cerebral infarction who underwent the cerebral CTPI and MRI within 3 days were enrolled in this study. The patients were divided into group A (45 cases, 80 kV-30 mAs with IMR2) and B (50 cases, 80 kV-10 mAs with IMR2). The normal hemispheres of each group were selected to evaluate respectively. The subjective image quality scores, effective dose (ED), CT value, SD, signal to noise ratio (SNR), contrast to noise ratio (CNR) and the perfusion parameters of the grey matter (GM) and white matter (WM) at ASPECTS level 2 and the display rate of different size of cerebral infarction were compared between the two groups. Results (1)The ED were 0.500, 0.167 mSv respectively for group A and B. (2)The subjective image quality scores in group A was rated as good, whereas group B was moderate and accompanied by concentric circles and black holes artifacts. There were no statistical significances in CT values of GM and WM, SNR of GM between two groups (P＞0.05). The SD values of GM and WM in group B were higher than those in group A (P＜0.05), and the SNR of WM and CNR in group B were lower than those in group A (P＜0.05). (3)There were no statistical significances in the CBV, TTP of GM and WM, and MTT of GM between two groups (P＞0.05). However, there were statistical significances in the CBF of GM and WM, and MTT of WM between two groups (P＜0.05). (4)The display rate of lacunar, focal and massive ischemic cerebral infarctions in group A was 4.44%, 100% and 100%, and group B was 4.00%, 100%, and 100%, respectively. Conclusion The image quality of IMR combined with 10 mAs in the cerebral CTPI wasn’t good, however, the radiation dose was ultra-low, focal and massive cerebral infarctions could be diagnosed, which have certain clinical application values for patients who with high risk of radiation injury and requiring multiple dynamic follow-up.