自适应统计迭代和基于模型的迭代重建算法对CT结肠成像图像质量和诊断的影响

Adaptive Statistical Iterative Reconstruction and Model-based Iterative Reconstruction on Image Quality and Diagnosis of CT Colonography

目的探讨自适应统计迭代重建算法（ASIR）和基于模型的迭代重建算法（MBIR）与滤波反投影（FBP）重建相比，对提高不同剂量CT结肠成像图像质量和息肉诊断率的影响。材料与方法离体猪结肠结扎获得30个模拟息肉，使用宝石CT在120kV、10-320mA管电流条件下采集数据，分别应用FBP、50％ASIR、100％ASIR和MBIR重建图像，比较不同条件下及不同重建算法图像噪声、对比噪声比（CNR）和息肉检出率。结果所有管电流条件下MBIR、50％ASIR和100％ASIR图像噪声均较FBP下降（辟21．860，P〈0．05），管电流10-70mA时，MBIR图像噪声较FBP、50％ASIR和100％ASIR下降（P〈0．05）；MBIR及100％ASIR图像CNR较FBP增高（F=4．209，P〈0．05），管电流10-80mA时，MBIR图像CNR较FBP、50％ASIR和100％ASIR增高（P〈0．05）。仿真内镜及虚拟分割图像在所有管电流条件下息肉检出率均为100％。结论ASIR和MBIR均可以显著提高CT结肠成像的图像质量，低剂量扫描时，MBIR提高图像质量的能力比ASIR更强，为低剂量CTC筛查结肠息肉提供了依据。

Purpose To compare adaptive statistical iterative reconstruction （ASIR） as well as model-based iterative reconstruction （MBIR） with filter back projection （FBP） in improving image quality and polyp detection rate of CT colonography （CTC） at different radiation doses. Matexials and Methods Thirty simulated polyps were created by ligating an isolated segment of pig colon. Data were acquired on a high definition CT scanner at different doses （10-320 mA at 120 kV） using four different reconstruction algorithms including FBP, 50% ASIR, 100% ASIR and MBIR to compare the image noise, the contrast to noise ratios （CNR） and detection rates of the polyps. Re, suits At all different tube current, 50% ASIR, 100% ASIR and MBIR significantly reduced image noise compared with FBP （F=21.860, P〈0.05）. At tube current of 10-70 mA, the image noise of MBIR were lower than that of FBP, 50% and 100% ASIR （P〈0.05）, while MBIR and 100% ASIR provided higher CNR than FBP （F=4.209,P〈0.05）. At tube current of 10-80 mA, MBIR had the highest CNR （P〈0.05）. At all tube currents, 100% of the 30 polyps were demonstrated on CT virtual colonoseopy and virtual dissection by all four reconstruction algorithm. Conclusion ASIR and MBIR can significantly improve CT colonography image quality. MBIR is superior to ASIR at low dose CT for CTC screening of colonic polyps.