非刚性三维校正技术在肝脏MR动态增强减影图像中的质量评价

Subtraction quality assessment of hepatic dynamic contrast enhanced MRI by using non-rigid 3D-registration for subtraction technique

目的探讨非刚性三维校正技术在肝脏MR动态增强减影图像质量评价中的应用。方法对20例患者的肝脏MR动态增强扫描非刚性三维校正前、后的减影图像质量进行评价,定性评价包括图像伪影情况和解剖错配程度;定量评价为测量各血管(腹主动脉,肝右动脉和肝左动脉,门静脉主干、左支、右支)校正前后平扫、动脉晚期、门静脉晚期的SNR,并绘制SNR的动态变化曲线,评估肝右动脉和肝左动脉、门静脉主干、左支、右支的SNR曲线吻合程度。结果校正前的减影图像均出现不同程度的解剖学错配导致的伪影,校正后的减影图像无明显解剖学错配伪影。校正前肝右动脉和肝左动脉的SNR动态变化曲线不吻合,校正后两者的动态变化曲线吻合;门静脉主干、左支、右支的SNR变化曲线在校正前后均吻合。结论非刚性三维校正技术可显著改善肝脏MRI动态增强减影图像的质量。

Objective To investigate the application of non-rigid 3D-registration technique in evaluation of the subtraction quality of hepatic dynamic contrast enhanced （DCE） MR images. Methods The subtraction quality of hepatic DCE MR images before and after correction in 20 cases were evaluated. Qualitative assessment was based on the presence of artifacts and the anatomical mismatch. In quantitative assessment, the SNR of the vessels （aorta, left and right hepatic arteries, portal vein and left, right portal veins） on the unenhanced, arterial and portal venous phase before and after correction were measured. SNR variation curves were drawn. The fitness of the SNR variation curves between left and right hepatic arter- ies, between portal vein and left, right portal veins were evaluated. Results Before correction, all of the 20 cases demon- strated different degrees of artifacts caused by anatomical mismatch. After correction, there were no obvious anatomical mismatch or artifacts. SNR variation curves of left and right hepatic arteries were mismatched before correction but were well matching after correction. SNR variation curves of portal vein and left, right portal veins were matching before and af- ter correction. Conclusion The non-rigid registration technique can significantly improve the overall substraction quality of liver DCE MRI.