摘要：
Objective To investigate the application value of three-dimensional(3D) heavily T2 weighted turbo spin echo(T2-SPACE) imaging technique in differential diagnosis of malignant and benign parotid tumors. Methods A total of 51 patients with parotid tumors were prospectively recruited from June 2015 to December 2017 in Ningbo No. 2 Hospital. There were 23 males and 28 females, aged from 16 to 74 years. All the patients were scanned by routine MRI sequences and heavily T2-SPACE sequence. Imaging data were post-processed with 3D multiplane reformation, and facial nerve and parotid gland were reformatted with curved planar reformation. Tumor location, morphology, margin, cystic necrosis and signal characteristics were observed on heavily T2-SPACE imaging. By analyzing the position relationship between tumor and parotid gland or facial nerve on routine MRI and heavily T2-SPACE sequences, benign parotid tumors were distinguished from malignant tumors. The accuracy rate was also compared to pathological findings, which is regarded as golden standard. Results Heavily T2-SPACE images shows 55 lesions were included in 51 patients. Twenty-five lesions were located in the superficial lobe, 16 lesions in the deep lobe,14 lesions across the crack. The image findings of the 55 lesions included: regular shape and well-defined margin in 34 lesions, irregular shape and indistinct margin in 21 lesions, heterogeneous intensity with cystic necrosis in 31 lesions. The number of facial nerve displayed on routine MRI T1 , T2 sequence and heavily T2-SPACE sequence was 39, 41, 53 sides, respectively, and parotid gland was 32, 45, 54 sides, which illustrated that heavily T2-SPACE sequence was able to find more facial nerve and parotid gland and showed clearer image. Among the 55 lesions, 34 lesions were diagnosed benign and 21 lesions were diagnosed malignant on routine MRI sequence, whereas 35 lesions were diagnosed benign and 20 lesions diagnosed malignant on heavily T2-SPACE sequence. According to pathological result (36 lesions benign, 19 lesions malignant), the accuracy rate of benign and malignant on routine MRI was 75. 0％(27/36), 12/19, and the total accuracy was 70. 9％(39/55), meanwhile the accuracy rate of heavily T2-SPACE sequence was 88. 9％(32/36), 16/19 and 87. 3％(48/55), respectively. Diagnostic accuracy was improved by using heavily T2-SPACE sequence with statistical difference ( x2 =7. 111, P <0. 05) . Conclusions Tumor location, margin, internal signal and position relations between parotid and facial nerve or parotid duct are better demonstrated on heavily T2-SPACE images, meanwhile, certain value is found in differential diagnosis of malignant and benign tumors, operation strategy, protection of facial nerve and prognosis judgement by using heavily T2-SPACE sequence, which is worthy to be widely applied in MR examination of parotid gland.%目的 探讨MR三维重T2加权可变翻转角快速自旋回波(T2-SPACE)成像技术在腮腺良恶性肿瘤鉴别诊断中的应用价值.方法 选取2015年6月—2017年12月宁波市第二医院收治的51例腮腺肿瘤患者进行前瞻性研究.其中男23例,女28例;年龄16～74岁.51例腮腺肿瘤患者均进行常规MR序列扫描和重T2-SPACE序列扫描,将采集图像信息进行三维多平面重建后处理,并进行面神经和腮腺导管曲面重建.在重T2-SPACE图像上观察腮腺肿瘤的位置、形态、边界、囊变坏死等情况,以及肿瘤在重T2-SPACE序列中的信号特点.在常规MRI和重T2-SPACE图像上分析肿瘤与腮腺导管、面神经的位置关系,判断腮腺肿瘤良恶性;以病理检查结果为金标准,对比两种方法诊断肿瘤良恶性的准确率.结果 重T2-SPACE序列图像显示:51例腮腺肿瘤患者中共55个病灶,其中病灶位于腮腺浅叶25个,深叶16个,跨叶14个;34个病灶形态尚规则、边界清晰,21个病灶形状不规则、边界模糊;31个病灶内信号混杂,可见大小不等囊变坏死区.55侧患病腮腺在常规MR T1 WI、T2 W1和重T2-SPACE序列上显示面神经分别为39、41、53侧,显示腮腺主导管分别为32、45、54侧;与常规MRI T1 WI、T2 W1比较,重T2-SPACE序列显示面神经、腮腺主导管数量更多,信号更清晰.55个病灶中,常规MRI序列诊断良性病灶34个、恶性病灶21个,重T2-SPACE序列诊断良性病灶35个、恶性病灶20个.以病理检查结果(良性病灶36个、恶性病灶19个)为金标准,常规MRI诊断肿瘤良性和恶性的准确率分别为75.0％(27/36)、12/19,总体准确率为70.9％(39/55);重T2-SPACE序列诊断肿瘤良性和恶性的准确率为88.9％(32/36)、16/19,总体准确率为87.3％(48/55).采用重T2-SPACE序列诊断腮腺肿瘤良恶性的总体准确率高于常规MRI序列,差异有统计学意义(x2=7.111,P<0.05).结论 重T2-SPACE序列可以清晰显示腮腺肿瘤的位置、边缘及内部信号情况,可清晰显示腮腺肿瘤与面神经、腮腺导管的位置关系,对肿瘤良恶性判断、手术方案制定、术中面神经的保护及患者预后判断等具有一定的价值,值得在腮腺MR检查中推广应用.
