迭代重建改善缺血性卒中患者低辐射CT 灌注成像的成像质量

目的：探讨 iDose4迭代重建技术能否提高低辐射剂量全脑 CT 灌注成像（ CT perfusion, CTP）的成像质量。方法连续收集临床拟诊为缺血性卒中患者35例，采用256层Brilance iCT行低辐射剂量全脑CTP，并采用滤波反投影（filtered back-projection, FBP）和iDose4算法进行图像重建。比较2种重建算法图像的噪声和信噪比以及各参数图的成像质量。结果全脑CTP的有效剂量为2.2 mSv。与FBP相比，iDose4 Tmax图中各感兴趣区噪声均显著下降（P＜0.05），信噪比显著增高（ P＜0.05）。 FBP 成像质量评分（中位数，四分位数间距）均显著低于 iDose4组：脑血流量（cerebral blood flow , CBF）图5.00（3.00~6.00）分对6.00（5.00~6.00）分；Z=－2.784，P=0.005]、脑血容量（cerebral blood volume, CBV）图6.00（5.00~6.00）分对6.00（6.00~7.00）分；Z=－3.674， P<0.001]和平均通过时间（ mean transit time, MTT ）图4.00（3.00~5.00）分对5.00（4.00~6.00）分；Z=－3.394，P=0.001]。 FBP 重建的质量差的CBF 图（34.3％对11.4％；χ2=7.036，P=0.030）、CBV图（11.4％对2.9％；χ2=7.485，P=0.024）和MTT 图（28.6％对11.4％；χ2=5.318，P=0.070）所占的比例均显著高于iDose4。结论 iDose4迭代重建技术可改善低辐射剂量CTP的成像质量。

Iterative reconstruction improves imaging quality of low er -radiation CT perfusion in patients w ith acute ischemic stroke

Objective To investigate w hether the iterative reconstruction (iDose 4 ) technique improves imaging quality of the low-radiation-dose w hole brain CT perfusion (CTP). Methods Thirty-five consecutive patients w ith clinical y suspected ischemic stroke w ere col ected. Bril iance 256 iCT w as used to perform low-radiation-dose w hole brain CTP, and the filtered back projection (FBP) and iDose 4 algorithm w ere used to conduct image reconstruction. The noise and signal to noise ratio of the 2 kinds of reconstruction algorithms, as w el as the imaging quality of each parameter map w ere compared. Results The effective dose of the w hole brain CTP w as 2.2 mSv. Compared w ith FBP, the noise of each region of interest in the iDose4 Tmax map was decreased significantly ( P<0.05) and the signal to noise ratio was increased significantly (P<0.05). The imaging quality scores (median, interquartile range) reconstructed by FPB group w ere significantly low er than by iDose 4 for cerebral blood flow (CBF) map ( 5.00 3.00-6.00]vs. 6.00 5.00-6.00]; Z= -2.784, P=0.005), cerebral blood volume (CBV) map ( 6.00 5.00-6.00] vs. 6.00 6.00-7.00]; Z= -3.674, P<0.001), and mean transit time (MTT) map (4.00 3.00-5.00] vs. 5.00 4.00-6.00]; Z=3.394, P=0.001). The proportions of the poor quality in CBF map ( 34.3%vs. 11.4%;χ2 =7.036, P=0.030), CBV map (11.4%vs.2.9%; χ2 =7.485, P=0.024 ) and MTT map (28.6%vs.11.4%;χ2 =5.318, P=0.070) reconstructed by FBP w ere significantly higher than by iDose 4 . Conclusions The iDose4 technique may improve imaging quality of low er-radiation-dose CTP.