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目的通过选择优化动脉作为动脉输入函数(AIF)以及对静脉输出函数(VOF)必要性的再评估来评价CT灌注(CTP)的准确性及可重复性。方法评估44例急性缺血性卒中病人应用256层多层CT(MDCT)的CT平扫、CTP及CT血管成像检查。分别选择大脑前动脉(ACA)、大脑中动脉(MCA)、颈内动脉(ICA)以及基底动脉作为AIF。随后,应用多重方差分析以及配对t检验对AIF时间-强化曲线下面积(AUCAIF)及定量灌注参数进行分析。比较使用与不使用VOF的灌注参数(配对t检验)来检验VOF能否被忽略,以评价CTP的可重复性。结果不同AIF所得的AUCAIF及灌注参数具有明显差异(P<0.0001)。颈内动脉的AUCAIF最大,平均通过时间(MTT)最高并且脑血流量(CBF)最低,而基底动脉的脑血容量(CBV)最低。不使用VOF在66%病人的同侧(分别为P<0.0001和P=0.007)及对侧大脑半球(分别为P<0.0001和P=0.019)的CBV及CBF更高。结论选用ICA作为AIF并继续应用VOF可以提高CTP的准确性。要点①灌注成像日趋成为MDCT的一个重要方式。②应用256层MDCT灌注成像评估血管输入函数。③选用不同的AIF会引起量化值的变化。④将颈内动脉作为AIF可以提供最佳的灌注值。⑤忽略静脉输出函数会降低CTP的可靠性。
Objective To evaluate the accuracy and repeatability of CT perfusion (CTP) by choosing the optimal arterial input function (AIF) and the need for venous output function (VOF) reassessment. Methods Forty-four patients with acute ischemic stroke underwent CT scan, CTP and CT angiography with 256-slice multi-slice CT (MDCT). Anterior cerebral artery (ACA), middle cerebral artery (MCA), internal carotid artery (ICA) and basilar artery were selected as AIF. Subsequently, multivariate ANOVA and paired t-test were used to analyze AUC-AUC and perfusion parameters. VOF perfusion parameters (paired t-test) were compared with or without VOF to test whether VOF could be ignored to assess CTP repeatability. Results The differences of AUCAIF and perfusion parameters between different AIF groups were significant (P <0.0001). The internal carotid artery had the highest AUCAIF with the highest mean transit time (MTT) and lowest cerebral blood flow (CBF), while the basilar artery had the lowest cerebrovascular volume (CBV). The VOF was higher for CBV and CBF without the VOF on the ipsilateral side of 66% of the patients (P <0.0001 and P = 0.007, respectively) and in the contralateral hemisphere (P <0.0001 and P = 0.019, respectively) Conclusion ICA as an AIF and continue to use VOF can improve the accuracy of CTP. Key points ① perfusion imaging has become an important way of MDCT. ② 256-slice MDCT perfusion imaging assessment of vascular input function. ③ choose a different AIF will cause quantitative changes. ④ The internal carotid artery as AIF can provide the best perfusion value. ⑤ Ignoring the intravenous output function will reduce the reliability of CTP.