胃癌磁共振表观扩散系数测量方法的对照研究

目的探讨小ROI局部测量法（Regional measurement，RM）与边缘勾勒整体测量法（Whole measurement，WM）所测得胃癌磁共振表观扩散系数值（apparent diffusion coefficient，ADC）的差异及其重复测量的一致性，比较两种测量方法ADc值反映胃癌侵袭性的效能。方法搜集手术病理证实胃癌55例，行常规MEI平扫及DWMRI检查。b值取1000s／mm^2。两名医师各自独立采用RM和WM两种方法测量胃癌癌肿ADC值。BIand—Altman法比较两名医师相同测量方法测得ADC值的一致性。以病理胃癌生长方式为评价癌肿侵袭性指标，以ROC曲线评价两种测量方法ADC值判断癌肿侵袭性的效能。结果RM法测得胃癌癌肿ADD值为024±030）×10^-3mm^2／s（观测者1）及（1.28±0.31）×10^-3mm^2／s（观测者2）；WM法测得胃癌癌肿ADC值为（141±030）×10^-3mm^2／s（观测者I）及（1.44±0.33）×10^-3mm^2／s（观测者2）。两名观测者采用RM法测得ADC值均低于WM法（观测者1：t=-10202．P〈0.001；观察者2：t=-8732，p〈0.001）。两种ADC值测量方法在两名观测者问均具有较好的一致性，其中RM法略优于WM法。RM法测得ADC值判断胃癌弥漫型生长的ROC曲线下面积为0.863，略高于WM法的0.828。结论小ROI局部测量法与边缘勾勒整体测量法所测得胃癌ADC值在不同测量者间具有较好的一致性，其中局部测量法ADC值反映癌肿侵袭性的能力较高。

A Comparison Study of Apparent Diffusion Coefficient Measurement Methods in Patients with Gastric Cancer

Objective To investigate the difference and repeatability of apparent diffusion coefficient （ADC） measurement of gastric cancer with small ROI regional measurement （RM） and margin-outline whole-part measurement （WM） methods, and compare the efficacy of ADC by two measurement methods in the evaluation of cancer invasive potential. Methods MR/ examinations were performed on 55 patients with gastric cancer proved by pathology. The b value of DW-MRI was 1000s/ram2. Two investigators measured the ADC values of gastric cancer used RM and WM methods independently. The Bland-Altman analysis was employed to compare the repeatability of ADC measurement. ROC curves were employed to compare the efficacy of two ADC measurement methods in the evaluation of cancer invasive potential. Results The ADCs were （1.24±0.30）×10^-3mm^2/s （observer l） and （1.28±0.31）× 10^-3mm^2/s （observer 2） by RM method; and were （1.41±0.30）× 10^-3mm^2/s（observer 1） and （1.44±0.33）× 10^-3mm^2/ s （observer 2） by WM method. The ADCs were lower used RM method than that with WM method （observer 1： t=-10.202, P〈0.001; observer 2： t=-8.732, P〈0.001）. There was good consistency between two observers used both methods, of which RM was slightly better than WM. The AUC of ADCs by RM method to judge the diffusely infiltrative pattern of gastric cancer was 0.863, which was slightly higher than that of WM method with an AUC of 0.828. Conclusion There is good consistency of ADC between different methods of regional measurement and whole-part measurement. The ADC measured by regional measurement method has better efficacy in the evaluation of cancer invasive potential.