迭代重建方法在低剂量全脑灌注CT成像及血管成像的可行性探讨

Feasibility of low-dose in entire brain perfusion imaging and CT angiography by iterative reconstruction

目的探讨迭代重建方法(iterative reconstruction algorithms,iDose4)对低剂量全脑灌注成像及血管成像的实用性及可行性。方法 63例患者进行脑CT灌注扫描,管电流为200 mA,按不同管电压分为3组,120 kV组17例、100 kV组21例,80 kV组25例,100 kV组、80 kV组原始数据分别利用iDose4level 4及level 5重建方法进行重建,根据3组原始数据及重建后数据的CT值及SD值计算出对比信噪比(contrast-to-noise ratios,CNR),然后重建出灌注图像(CTP)及血管成像(CTA),由2名高年资放射诊断医师利用5分制进行盲评(5=最好,1=最差)。结果 3组辐射剂量比较差异有统计学意义(P<0.001),平扫及增强峰值时100 kV及80 kV组重建前、后CNR比较差异有统计学意义,平扫120 kV、100kV重建后、80 kV重建后3组CNR方差分析比较差异有统计学意义(P<0.05),其中100 kV重建后及80kV重建后两组比较差异无统计学意义(P>0.05),增强峰值时3组间比较差异无统计学意义(P>0.05),CTP、CTA评分3组方差分析比较无统计学意义(P>0.05)。结论 iDose4重建方法作为一个重要的重建方法可以在大幅度降低辐射剂量的同时,提高图像质量,完成脑灌注成像及血管成像的诊断。

Objective To investigate the practicability of low-dose in entire brain.perfusion im- aging and CT angiography by iterative reconstruction. Methods Brain perfusion CT scan was performed in 63 patients. Tube current was set to 200 mA, according to the different tube volt- ages patients were divided into 3 groups, 17 patients underwent 120 kV, 200 mA, 21 patients underwent 100 kV, 200 mA, 25 patients underwent 80 kV, 200 mA. Iterative reconstructions were provided with level 4 in 100 kV group, and level 5 in 80 kV group. According to the orig- inal data and reconstructed data of CT value and SD value to calculate the contrast-to-noise rati- os（CNR）. The image quality of perfusion image （CTP） and computed tomography angiography （CTA） was assessed by 2 senior radiologists using 5 point system for blind assessment （5 = best to 1 = worse）. Results The radiation dose of 3 groups had statistical significant difference （ P 〈 0. 001 ）. CNR of 100 kV and 80 kV groups had significant difference in plain scaning and enhance scaning between pro-recondition and post-recondition, P 〈 0.05. The CNR of thegroups 120 kV, reconstruction data of 100 kV, reconstruction data of 80 kV had statistical sig- nificance in plain scaning, but no statistical significance between reconstruction data of 100 kV and 80 kV（P 〉 0.05）. CNR and CTP, CTA scores of 120 kV, reconstruction data of 100 kV, reconstruction data of 80 kV had no statistical significance in plain scaning （P 〉 0. 05 ）. Con- clusion IDose4 reconstruction as an important reconstruction method can greatly reduce the ra- diation dose and improve the image quality.