三维非刚性配准提高肝脏动态增强MR测量可重复性的初步研究

A Preliminary Study on Improvement of Repeatability of Three-Diamensional Non-Rigid Registration for Heptic Dynamic Contrast-Enhanced MR Data

目的探讨三维非刚性配准在提高肝脏动态增强MR应用中的可重复性。方法前瞻性分析18例行动态增强MRI检查的肝硬化背景肝细胞肝癌患者的资料。使用Omni Kinetics软件对获得的图像进行三维非刚性配准,采用Extended Tofts双输入模型对配准前、后的图像进行计算。由两位观测者采用盲法测量配准前、后同层面病灶、肝脏及竖脊肌的K^(trans)、K_(ep)值,并对测量值的变异度、一致性进行组间(两位观测者之间)及组内(一位观测者间隔一周测量两次)比较,并使用Bland-Altman Plot对组间和组内测量值的可重复性进行分析。结果 18例三维非刚性配准后同层不同期两幅图像有差异,像素均值为32761±13575,小于配准前(43202±20884),差异有统计学意义(t=2.637,P<0.05)。相对差值百分比箱图显示组间及组内病灶、肝脏、竖脊肌K^(trans)、K_(ep)均数配准后差异均小于配准前,离群值及极值减少或消失;配准后组内竖脊肌K^(trans)和K_(ep)的四分位间距稍增大,余四分位间距均变小;配准后组间四分位间距均变小。配准后组内、组间病灶、肝脏、竖脊肌K^(trans)、K_(ep)可重复性均提高,均值差变小。结论三维非刚性配准可提高病灶、肝脏及竖脊肌K^(trans)、K_(ep)的可重复性。

Objective To assess repeatability of three-dimensional non-rigid registration for hepatic dynamic contrastenhanced MRI data. Methods 18 patients with confirmed hepatocellular carcinoma under dynamic contrast-enhanced MR examination were analyzed prospectively. All the data were input Omni Kinetics software to process three-diamensional nonrigid registration. Pre and post registration data were calculated respectively with Extended Tofts dual-input model to acquire Ktrans,Kepof lesion,liver and sacrospinal muscle in the same slice. Inter and intra variations,repeatability and concordance correlation were performed for quantitative parameters. Results There is significant difference between means of discrepant pixels in same slice with different phases of pre and post registration data（ respectively 32761 ± 13575,43202 ±20884）（ t = 2. 637,P 〈 0. 05）. Relative percent difference box chart showed that means of inter and intra Ktrans,Kepof lesion,liver and sacrospinal muscle after registration was smaller than that before registration. Outliers and extreme value reduced or disappeared after registration. Quartile range of intra Ktrans,Kepof sacrospinal muscle increased slightly and others decreased. Quartile range of inter Ktrans,Kepof lesion,liver and sacrospinal muscle all decreased. Repeatability of Ktrans,Kepof inter- and intra lesion,liver and sacrospinal muscle was improved after registration. Conclusion Repeatability of Ktrans、Kepof lesion,liver and sacrospinal muscle was improved with Extended Tofts dual-input model after three-diamensional non-rigid registration compared with pre registration.