迭代模型重建技术在肺动脉“双低”成像中的应用研究

目的：探讨迭代模型重建(IMR)技术在肺动脉低剂量、低对比剂成像中的应用价值。方法对60例临床怀疑肺动脉栓塞(PE)患者行256层螺旋CT肺动脉成像,根据随机表法将患者随机分为实验组、对照组,每组30例。实验组原始数据分别采用滤波反投射(FBP)、IMR技术重建图像(A、B组),对照组原始数据采用 FBP 重建(C 组)。采用5分制方法评价肺动脉主干及其分支的图像质量,测量并计算肺动脉强化值(CT 值)、图像噪声值、图像信噪比(SNR)、对比噪声比(CNR),记录 CT 容积剂量指数(CTDIvol)、剂量长度乘积(DLP),计算有效剂量(ED)。比较 A组与 B组,B组与 C组肺动脉 CT值、图像噪声、SNR、CNR 及主观图像质量。结果实验组与对照组体质量指数(BMI)差异无统计学意义(P=0.096)。实验组CTDIvol、ED低于对照组(P<0.001)。A、B组肺动脉CT值差异无统计学意义(P=0.999),B组肺动脉CT值高于C组(P=0.005)。B组图像噪声明显低于A组(P<0.001),B组图像噪声高于C组(P<0.001)。B组 SNR、CNR高于 A组(P<0.001),B、C组 SNR、CNR差异无统计学意义(P=0.831,P=0.958)。B组图像可诊断率、优良率高于 A组(P<0.001),B、C 2组图像优良率差异无统计学意义(P=1.000)。结论肺动脉“双低”成像扫描模式联合更优化的迭代重建技术的应用,能够保证图像质量的同时大幅度降低患者辐射剂量及对比剂应用。

Application of iterative model reconstruction technique in CT pulmonary angiography with lower radiation dose and lower contrast medium

Objective To observe the value of iterative model reconstruction(IMR)technique in CT pulmonary angiography (CTPA)with lower radiation dose and lower contrast medium.Methods 60 patients with clinical suspicion of pulmonary embolism underwent 256-slice CTPA were prospectively enrolled.The raw data of test group(n=30)were reconstructed by filtered back projection (FBP)(group A)and IMR technique (group B).And the raw data of control group(n=30)were reconstructed by FBP(group C).The values of volume CT dose index(CTDIvol),effective radiation dose (ED)were recorded and calculated.The image quality parameters:CT value,image noise,signal-to-noise (SNR),contrast-to-noise ratio (CNR)and subjective image score(from one to five)were measured and compared between group A and B,B and C.Results The BMI was no statistically significant difierenee between two groups(P=0.001).The CTDIvol, ED on test group were respectively lower than that on control(P<0.001).The CT value was no statistically significant difierenee between group A and B(P=0.999).The CT valueon group B was higher than that on group C(P=0.005).The image noise on group B was lower than that on group A(P<0.001),but which was higher than that on group C(P<0.096).The SNR,CNR on group B were higher than that on group A(P<0.001).The SNR,CNR did not differ significantly between B and C(P=0.831,P=0.958).The diagnosable rate and good quality rate on group B were higher than that on group A(P<0.001),and there were no significantly diferent between B and C(P=1.000).Conclusion The application of optimized IMR technique can improve image quality at lower radiation dose and lower contrast medium for CTPA.