多模态磁共振成像对脾脏实性良恶性肿瘤鉴别诊断的价值

The value of multimodal MRI to identify solid benign and malignant splenic tumors

目的:探讨多模态磁共振成像对脾脏实性良恶性肿瘤鉴别的价值。资料与方法 :经临床或病理证实的脾脏良性肿瘤21例、恶性肿瘤14例,观察两组病例的T1WI,T2WI,扩散加权成像(DWI),增强T2*加权血管成像(ESWAN)序列后处理得到的幅度图、相位图、R2*图中肿瘤信号强度,以及肝脏快速容积成像(LAVA)多期动态增强扫描序列肿瘤强化类型,并应用卡方检验比较两组各序列信号强度及强化类型的差异。由两位观察者分别测量两组病例DWI序列的表观弥散系数(ADC)值以及ESWAN序列的相位值、R2*值,使用组内相关系数(ICC)检验两位观察者测量数据的一致性,并应用非参数Mann-Whitney U检验比较两组各参数间有无差异,根据ROC曲线下面积评估ADC值、相位值及R2*值对良恶性肿瘤鉴别的效能,找出相应界值。结果:脾脏实性良恶性肿瘤在T1WI、T2WI序列上信号强度没有差异,在DWI序列及ESWAN序列的幅度图、相位图及R2*图上,恶性肿瘤信号复杂,以混杂信号为主;两组病例在LAVA序列强化类型存在差异,但有重叠;两位观察者获得两组图像的ADC值、相位值及R2*值数据结果一致性良好,良恶性肿瘤的ADC值、相位值及R2*值分别为(1.80±0.44)×10-3 mm2/s和(1.40±0.40)×10-3mm2/s,0.071±0.037和-0.003±0.119,(13.46±9.00)Hz和(42.09±19.82)Hz,差异具有统计学意义(P值均<0.05);其ROC曲线下面积为0.754、0.721、0.941,ADC值≥1.23×10-3mm2/s、相位值≥0.440、R2*值≤20.47 Hz为诊断良性肿瘤的界值。结论:脾脏实性良恶性肿瘤在MR常规序列(平扫及增强)征象重叠,缺乏特异性,但恶性肿瘤在DWI及ESWAN后处理图像上混杂信号较多,ADC值、相位值及R2*值可以作为定量指标对良恶性肿瘤进行鉴别,且R2*值更具价值。

Objective： To explore the value of multimodal MRI to identify solid benign and malignant splenic tumors. Materials and Methods： The clinical and medical imaging data of 21 cases of benign splenic tumors and 14 cases of malig- nant tumors were analyzed retrospectively. Scanning sequences included： TtWI, T2WI, liver acquisition with volume acceleration （LAVA）, diffusion weighted imaging（DWI） and enhanced T2 star weighted angiography（ESWAN）. The phase, magnitude and R2＊ maps were generated from the original ESWAN data. The signal intensity on T^WI, T2WI, DWI, and in phase, magnitude, R2＊ maps as well as tumor characteristics on LAVA sequence of the two groups were tested by Chi-square test. The values of apparent diffusion coefficient （ADC）, phase and R2＊ of the two groups were measured by two observers, and the consistency measured by two observers was tested by the intra-class correlation coefficients（ICC）. Mann-Whitney U test was used to com- pare various parameters of the two groups. Receiver operator characteristic（ROC） curve was used to calculate the cut-off value of ADC, phase, R2＊ and performance of ADC, phase, R2＊ value for distinguishing these solid benign and malignant tumors. Results： The signal intensity of the solid benign and malignant tumors on TIWI and T2WI had no difference. However, the signal intensity of malignant tumors on DWI, phase, magnitude on ESWAN and R2＊ maps had more complicated mixed signal intensity; the two groups showed differences in the enhanced pattern on LAVA sequence, but with overlap. The ADC values, phase values and R2＊ values of the two groups obtained from the two observers were in good consistency （ICC value 〉0.75. The ADC of the benign and malignant tumors were （1.80＋0.44）x10-3 mm2/s and （1.40-＋0.40）x10-3 mm2/s with phase of 0.071_＋ 0.037 and -0.003＋0.119, R2＊ values of （13.46＋9.00）Hz and （42.09＋19.82）Hz respectively, all showing statistically significant differences （all P〈0.05）. The AUC of the ADC, phase and R2＊ values were 0.754, 0.721 and 0.941, and the best cut-off val- ues for ADC, phase and R2＊ in characterizing benign and malignant tumors were 1.23x10-3 mm2/s, 0.440 and 20.47 Hz, re- spectively. Conclusion： The solid malignant splenic tumors show more complicated signals than benign tumors on DWI and ESWAN. The ADC, phase and R2＊ values can be used as quantitative indexes to identify benign and malignant splenic tu-mors, and R2＊ values were more valuable.