全模型迭代重建技术在“双低”弓上CTA成像中的应用

Investigation of Iterative Model Reconstruction in Supraaortic Arteries CTA with Low Dose and Low Iodine Load

目的:探讨全模型迭代重建(iteraUve model reconstruction,iMR)技术在主动脉弓上CTA成像中的应用价值。方法:连续收录2017年2月-2018年12月在我院Philips Brilliant iCT上行弓上CTA扫描的患者60例,随机采用常规法和双低法扫描各30例。60例分别用iDose4和iMR1进行重建,得到4组图像。测量比较4组图像主动脉、左右颈动脉、大脑中动脉、基底动脉和椎动脉增强后平均CT值及计算图像信噪比(SNR)及对比噪声比(CNR),并对图像质量进行主观评分。采用SPSS22软件进行统计学分析,t检验两两比较各组间CT值、SNR、CNR差异性,卡方检验两两比较各组间主观评分差异性,并用秩和检验检验一致性。结果:常规剂量扫描中,A组iDose重建图像与B组iMR重建图像的各节段血管平均CT值无显著差异,双低剂量扫描中,C组iDose重建图像与D组iMR重建图像的各节段血管平均CT值无显著差异;但D组图像SNR与CNR显著高于C组。运用iMR技术重建的D组双低剂量图像SNR与CNR也高于B组常规剂量图像。常规剂量及双低剂量下iMR图像质量主观评价均明显优干iDose图像质量。常规剂量和双低扫描法两者的iMR图像质量无明显差异。结论:在双低剂量条件下iMR重建图像的SNR及CNR仍优于iDose重建图像,值得在临床弓上CTA扫描中推广。

Purpose:To investigate the clinical value of iterative model reconstruction(iMR)in CTA imaging of supraaortic arteries.Methods:From February 2017 to December 2018,60 patients with supraaortic arteries CTA scan on Philips Brilliant iCT in our hospital were enrolled.Thirty patients were scanned by conventional method and 30 patients by double-low method.Sixty patients were reconstructed with iDose4 and iMR1,and four groups of images were obtained.The average CT values of aorta,left and right carotid artery,middle cerebral artery,basilar artery and vertebral artery were measured and compared.SNR and CNR were calculated.The image quality was subjectively evaluated.Statistical analysis was carried out by SPSS22 software.T-test was used to compare the differences of CT value,SNR and CNR between groups.Chi-square test was used to compare the differences of subjective scores between the four groups.Rank sum test was used to test the consistency.Results:For routine dosage scan,there was no significant difference in the average CT value of each blood vessel segment between group A with iDose reconstructed image and group B with iMR reconstructed image.For double low dosage scan,there was no significant difference in the average CT value of each blood vessel segment between group C with iDose reconstructed image and group D with iMR reconstructed image.But the SNR and CNR in group D were significantly higher than those in group C.The SNR and CNR of group D reconstructed by iMR were also higher than those of group B with routine dosage.The subjective evaluation of iMR image quality at routine dosage and double low dosage is significantly better than that of iDose image.No significant difference was found between the iMR image quality of routine dosage and double low scan.Conclusions:The SNR and CNR of iMR reconstructed images are better than those of iDose reconstructed images under the condition of double low dose.It is worth popularizing in clinical CTA scan of supraaortic arteries.