迭代重建算法CT灌注成像与CT血管造影在缺血性脑血管病中的诊断价值

摘要

目的利用迭代算法重建的头颅低剂量CT灌注扫描的容积数据重组CT血管造影（PCTA）图像，分析PCTA对脑内动脉的显示能力，探讨降低脑卒中CT检查辐射剂量的方法。资料与方法本研究为前瞻性研究，临床拟诊为缺血性脑血管病的55例患者（605个动脉血管节段），使用256层螺旋CT进行头颅CT平扫、迭代算法头颅低剂量CT灌注扫描和常规头颅CTA检查。每个病例均分析11个节段的脑动脉，以常规CTA结果为标准，评估PCTA对脑内动脉的显示情况。结果 CT灌注扫描有效剂量为2.12 mSv。CTA未见狭窄或狭窄程度<30%的580个节段血管中， PCTA仅1个节段血管显示与CTA不符；CTA提示狭窄程度≥30%但达闭塞的19个节段血管中，12个节段血管PCTA与CTA结果一致，PCTA夸大了另外7个节段血管的狭窄程度；CTA发现闭塞的6个节段血管与PCTA显示结果一致。PCTA与CTA对脑内动脉血管显示一致性检验的Kw值均>0.75。结论迭代算法的头颅CT灌注扫描辐射剂量明显减低，而且从CT灌注的容积数据重组的动脉图像与CTA结果具有较高的一致性，可以满足临床诊断需要。%Purpose To reconstruct perfusion computerized tomography angiography (PCTA) images from the volume data of low-dose brain CT perfusion scan with iterative reconstruction algorithm, to analyze the capability of PCTA on the display of brain arteries, and to explore the methods to reduce the radiation dose for stroke CT examinations. Materials and Methods This was a prospective study, 55 patients (605 arterial segments) with clinical diagnosis of ischemic cerebrovascular disease underwent cranial CT scan, iterative algorithm low-dose brain CT perfusion scan and conventional cranial CTA examinations using a 256-slice spiral CT. 11 segments of the cerebral artery in each case were analyzed using conventional CTA results as the reference standard to assess the display of brain arteries in PCTA. Results Effective dose of CT perfusion scan was 2.12 mSv. Among the 580 vessel segments which CTA showed no stenosis or stenosis<30%, only one vessel segment of PCTA was inconsistent with CTA; among the 19 vessel segments which CTA showed stenosis≥30%but not occluded, results of 12 vessel segments in PCTA were consistent with CTA, while the stenosis states were exaggerated by PCTA in the other seven vessel segments;results of the two methods were consistent in six vessel segments which was found occluded by CTA. Kw values were >0.75 for the consistency test between PCTA and CTA on the display of brain arteries. Conclusion Radiation dose of iterative algorithm cranial CT perfusion scan is significantly lower, and the images reconstructed from the volume data of perfusion CT are highly consistent with the CTA results, thus are able to meet the needs of the clinical diagnosis.