磁共振波谱及扩散加权成像在唾液腺肿瘤诊断中的价值

目的 回顾性分析、评价氢质子磁共振波谱(~1H-MRS)及扩散加权成像(DWI)在鉴别唾液腺良性或恶性肿瘤中的价值.资料与方法 应用1.5 TMR成像仪,对39例唾液腺肿瘤患者进行常规MRI、DWI及~1H-MRS检查,(1)DWI采用单次激发自旋回波一回波平面成像(SE-EPI)序列,扩散敏感系数(b值)为0 s/mm~2及1000 s/mm~2,并计算每例患者平均表观扩散系数(ADC)值和高、中、低ADC值所占的比例,(2)~1H-MRS采用单体素点分辨表面线圈(PRESS)序列,TR 1500 ms,TE 136 ms,在谱线中计算胆碱与肌酸的比值(Cho/Cr).最后与肿瘤的组织病理学结果进行对比,进行非参数秩和检验.结果 39例唾液腺肿瘤患者均获得了满意的检查结果,其中良性肿瘤31例(混合瘤21例,腺淋巴瘤10例),恶性肿瘤8例(腺囊腺癌3例、黏液表皮样癌3例、混合腺癌1例、恶性淋巴瘤1例).(1)DWI:ADC图提示良性肿瘤与恶性肿瘤的平均ADC值分别为(1.65±0.41)×10~(-3)mm~2/s和(1.15±0.39)×10~(-3) mm~2/s,其间无明显差异,但良性肿瘤ADC值增高的区域则明显多于恶性肿瘤,尤其是混合瘤.(2)~1H-MRS:在TE为136 ms时共获得满意的波谱曲线35例,计算得出恶性肿瘤、腺淋巴瘤、混合瘤的Cho/Cr分别为1.69±0.51、5.89±1.42、2.81±0.72,恶性肿瘤、腺淋巴瘤、混合瘤之间均存在显著差异.结论 DWI及~1H-MRS可以作为鉴别唾液腺肿瘤的特异性检查手段,但仍需要大量研究样本来进行验证.

The Value of ~1H-MRS and DWI in Differentiating of Salivary Gland Tumors

Objective To investigate the value of ~1H-MRS and DWI in differentiating the nature of salivary gland tumors. Materials and Methods The conventional MR imaging(MRI) ,diffusion weighted imaging (DWI) and ~1H-MRS Spectroscopy were performed in 39 cases of salivary gland tumors using 1.5T imager. DWI were performed using single shot SE-EPI sequence with two different b values (0 s/mm~2 and 1000 s/mm~2). ~1H-MRS were performed using PRESS sequence with TR/TE 1500ms/136ms. The ADCs and ratio of Cho/Cr were compared with historical feathers of the excised tumors. The results were statistically analyzed using a nonparametric test. Results Successful MRS were acquired in 39 patients with a total of 31 benign SGTs (21 pleomorphic adenomas, 10 Warthin tumors) and 8 malignant tumors (2 adenoid carcinomas,3 mucoepidermoid carcinomas, 1 carcinoma ex pleomorphic adenoma,1 malignant lymphoma.). (1) DWI:Mean ADC values were (1.65±0.41) × 10~(-3) mm~2/s in benign salivary gland tumors and (1.15± 0.39) × 10~(-3) mm~2/s in malignant salivary gland tumors. No significant difference in mean ADC values was found between benign and malignant tumors. However, mean ADC values usually increased in malignant tumors, especially in pleomorphic adenomas. (2)Singlevoxel ~1HMRS:At an echo time of 136mces,35 satisfied spectra were obtained. The mean value of Cho/Cr ratios were 1.69 ± 0.51,5.89 ±1.42, 2.81 ±0.72 for malignant tumors ,Warthin tumors and pleomorphic adenomas,respectively. Differences were significant between malignant tumors,Warthin tumors and pleomorphic adenomas. Conclusion DWI and ~1H-MRS may be useful to characterize SGTs, but a large study is required to validate these initial results.