肾上腺肿瘤不同b值DWI研究

目的：研究不同b值肾上腺肿瘤扩散加权成像（DWI）的表现,比较不同b值组表观扩散系数（ADC值）之间的差异,探讨最佳b值的选择及最佳b值组良恶性肿瘤的ADC值范围及阈值。方法：对23例经手术病理及临床证实的肾上腺肿瘤患者行平扫、DWI（b值分别取0、400、800和1000s/mm^2）,分别观察不同b值肿瘤信号的差异,同时测量不同b值肿瘤的ADC值并作统计学分析。结果：①b值为0s/mm^2时,DWI肿瘤的信号和T2WI一致,b值分别为400、800和1000s/mm^2,良性肿瘤随着b值的增高,信号逐渐减低,而恶性肿瘤随着b值的增高,信号变化不明显;②3个b值组,低b值组肾上腺肿瘤的平均ADC值最大,随着b值的增大,平均ADC值逐渐减小,并有统计学意义（F=13.543,P〈0.05）;③400～0s/mm^2b值组肾上腺良恶性肿瘤ADC值之间无统计学意义（t=-2.033,P=0.054）,而800～0s/mm^2b值组及1000～0s/mm^2b值组有统计学意义（t=-2.700,P=0.013;t=-3.529,P=0.002）;④以800～0s/mm^2b值组ADC值作为研究对象进行受试者工作特性（ROC）曲线分析,诊断阈值为0.986×10^-3mm^2/s,此阈值点对肾上腺良恶性病变诊断的敏感度为80%,特异度为78%。结论：b=800～0s/mm^2为较佳选择,此时良性肿瘤的平均ADC值为（1.138±0.180）×10^-3mm^2/s,恶性肿瘤的平均ADC值为（0.916±0.218）×10^-3mm^2/s;DWI对肾上腺肿瘤性质鉴别具有价值,是对常规MR检查有益的补充。

Study on Different b Values in MR Diffusion Weighted Imaging of Adrenal Tumors

Objective:To study the manifestations of MR diffusion weighted imaging(DWI) and to compare the differences of apparent diffusion coefficient(ADC) values of adrenal tumor in different b factors,so as to investigate the selection of optimal b factor as well as the range and threshold of ADC values of benign and malignant adrenal tumors with optimal b factor.Methods:A total of 23 patients with pathology or clinical proven adrenal tumor underwent MR plain and DWI scanning.Various b factor were set as 0,400,800 ...