低管电压结合迭代重建技术配合不同对比剂注射方案在冠状动脉CTA成像中的可行性研究

目的 探讨迭代重建技术（IDose⁴）在降低管电压配合不同对比剂碘流率注射方案下行冠状动脉CT血管成像（CCTA）的可行性。方法 对10只实验猪分别重复9次CCTA扫描[管电压分别为120 kV（A₁）、100 kV（A₂）、80 kV（A₃），对比剂碘流率分别约为1300 mgI/s（B₁）、1000 mgI/s（B₂）及750 mgI/s（B₃），两两组合成9组方案]；对原始图像分别采用滤波反投影法（FBP）及IDose⁴重建，将A₁B₁+FBP重建设为对照组。比较各组图像的主、客观指标。结果 在相同条件下，IDose⁴重建较FBP重建显著降低图像噪声、提高SNR及CNR（P均<0.001）。随管电压及碘流率的降低，图像噪声增大，SNR、CNR降低。采用IDose⁴重建，除A₃B₁、A₃B₂、A₃B₃组噪声仍明显增加外（P均<0.05），其余各组噪声、SNR、CNR均与对照组无统计学差异（P均>0.05）。采用FBP重建，A₃B₁、A₃B₂、A₃B₃组及A₂B₃组冠状动脉远段可诊断率较对照组明显减低（P均<0.05），而经IDose⁴重建后，除A₃B₃组冠状动脉远段可诊断率仍明显低于对照组（P=0.015）外，余各组均明显改善，与对照组无统计学差异（P均>0.05）。结论 采用IDose⁴重建结合低管电压及低碘流率行CCTA是可行的。

Feasibility of coronary artery CT angiography with low tube voltage combined with different iodine flow rate injection protocols by using iterative reconstruction algorithm

Objective To assess the feasibility of coronary computed tomography angiography (CCTA) at a low tube voltage and low iodine flow rate injection protocol by using iterative reconstruction algorithm. Methods Ten healthy swine underwent repeated CCTA with different combination of tube voltage (A₁,120 kV; A₂,100 kV; A₃, 80 kV) and iodine flow rate of contrast media (B₁, 1300 mgI/s; B₂, 1000 mgI/s; B₃, 750 mgI/s), resulting in 9 raw data sets. Each set of raw data was reconstructed with filter back projection (FBP) and iterative reconstruction algorithm (IDose⁴), respectively. Group A₁B₁ using FBP reconstruction was set as control group. Subjective and objective indicators of each group were compared. Results IDose⁴ reduced the image noise, enhanced SNR and CNR significantly in the same protocol as compared to FBP (all P<0.001). A reduction in the tube voltage and iodine flow rate of contrast medium caused increasing in image noise and decreasing in SNR and CNR. By using IDose⁴ reconstruction, except the image noise in group A₃B₁, A₃B₂ and group A₃B₃ was still obviously increased (all P<0.05), the image noise, SNR and CNR in all the other groups were no significantly different from those in the control group (all P>0.05). Under FBP reconstruction, the diagnosable rate of distal coronary segments in group A₃B₁, A₃B₂, A₃B₃ and group A₂B₃ was obviously reduced (all P<0.05). After using IDose⁴ reconstruction, there was no statistical difference from the control group (all P>0.05) except the diagnosable rate of distal coronary segments in A₃B₃ (P=0.015). Conclusion Compared to the FBP reconstruction, IDose⁴ reconstruction can significantly reduce image noise, improve SNR, CNR and subjective image scores.