IMR、iDose4 及FBP 结合不同管电压 冠状动脉CT 成像的实验研究

Assessment of IMR, iDose4 and FBP in coronary CT angiography performed at different tube energies: an animal study

摘要:

目的 探讨全模型迭代重建（IMR）、高级混合迭代重建（iDose4）及滤波反投影（FBP）重建 算法在不同管电压条件下冠状动脉CT 成像中对图像质量的影响。方法 选取小型猪5 只，每只猪均进行 120、100 及80 kV 管电压并分别作为A、B、C 组。前瞻性心电门控冠状动脉256 层螺旋CT 扫描，并将原始 数据进行FBP、iDose4 及IMR 重建算法，比较各组重建图像客观指标（包括噪声、信噪比、对比噪声比及左 主干开口处主动脉CT 值），并对图像质量进行主观评分。结果 不同管电压条件下IMR 重建较iDose4、FBP 重建噪声小（P <0.05），iDose4 较FBP 噪声大（P <0.05）；不同重建方法同一组内主观评分比较，差异有统计 学意义（P <0.05），且80 kV 条件下IMR 重建图像噪声较120 kV 条件下的iDose4、FBP 低（P <0.05）。C 组 辐射剂量仅为A 组的33.68%。结论 在冠状动脉CT 成像中，IMR 较iDose4 和FBP 显著提高图像质量，用 80 kV 低电压扫描结合IMR 重建方法既降低了辐射剂量，又提高了图像质量。

Abstract:

Objective To investigate the performance of a knowledge-based iterative reconstruction (iterative model reconstruction - IMR) compared to filtered back projection (FBP) and a hybrid iterative reconstruction technique (iDose4) in coronary CT angiography under different tube voltages. Methods Five miniature pigs underwent prospective axial ECG-gated coronary 256-slice spiral CT angiography at different tube voltages including 120, 100 and 80 kV (group A, B and C). All original data were reconstructed using the FBP, iDose4 and IMR algorithms. The objective indices of the reconstructed images, including image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and mean CT value of the aortic root were compared among the three groups reconstructed by the different algorithms. A 5-point scale was used to assess subjective image quality of coronary segments and images with a score of ≥ 4 as a good criterion. Results At all three tube voltages, the IMR algorithm consistently yielded a lower noise and a higher CNR than iDose4 and FBP (P < 0.05). The differences of subjective scores among different reconstruction methods in the same group were all statistically significant (P < 0.05). In addition, at 80 kv, the image noise in IMR reconstruction was lower than in iDose4 and FBP reconstructions at 120 kV (P < 0.05); the radiation dose in group C was only 33.68% of that in group A. Conclusions Compared to iDose4 and FBP algorithms, iterative model reconstruction (IMR) algorithm significantly improves the image quality of 256-slice coronary CT angiography. A combination of low tube voltage (80 kV) and IMR algorithm can help reduce radiation dose and improve image quality.