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

Iterative reconstruction improves imaging quality of lower-radiation CT perfusion in patients with acute ischemic stroke

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BrillanceiCT行低辐射剂量全脑CTP，并采用滤波反投影（fdtered 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2．2mSv。与FBP相比，iDose4Tmax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iDose。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 transittime，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％；X2=7．036，P=0．030）、CBV图（11．4％对2．9％；x2=7．485，P=0．024）和MTT图（28．6％对11．4％；X2=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。

Objective To investigate whether the iterative reconstruction （iDose4） technique improves imaging quality of the low-radiation-dose whole brain CT perfusion （CTP）. Methods Thirty-five consecutive patients with clinically suspected ischemic stroke were collected. Brilliance 256 iCT was used to perform low-radiation-dose whole brain CTP, and the f＇fltered back projection （FBP） and iDose4 algorithm were used to conduct image reconstruction. The noise and signal to noise ratio of the 2 kinds of reconstruction algorithms, as well as the imaging quality of each parameter map were compared.Results The effective dose of the whole brain CTP was 2.2 mSv. Compared with 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 were significantly lower than by iDose4 for cerebral blood flow （CBF） map （5.00 E3.00-6. 00]vs. 6. 00 [5.00-6. 00] ; Z = -2. 784, P =0. 005）, cerebral blood volume （CBV） map （6. 00 [5. 00-6. 001 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%;X2 =7.036, P=0.030）, CBV map （11.4% vs. 2.9%;X2 =7.485, P=0.024 ） and MTT map （28.6% vs. 11.4% ;X2 =5. 318, P =0. 070） reconstructed by FBP were significantly higher than by iDose4.Conclusions The iDose4 technique may improve imaging quality of lower-radiation-dose CTP.