Evaluation of Salivary Gland Function in Sjogren Syndrome with Diffusion-weighted MR Imaging and Dynamic MR Sialography

本研究应用拼接技术和动态唾液酸成像技术，评价弥散加权(DW)磁共振成像在干燥综合征(SS)患者唾液腺功能评价中的应用价值。DW磁共振成像参数为：TR=5.9ms，TE=65ms，层厚=6 mm，梯度因子b=205.38,1496.43秒/mm^2。根据DW图像感兴趣区域的信号强度计算腮腺ADC值。使用单次激发稀有序列获得动态MR唾液酸成像。动态MR腮腺造影的成像参数为：回声间隔=11.5毫秒，有效TE=1100毫秒，ETL=240，层厚=30 mm。在口腔内注射2毫升酒石酸后，立即获得连续5分钟的MR唾液相图。研究人群包括12名健康受试者和54名SS患者。所有患者均行唇腺活检和撒克逊试验。采用病灶计分进行组织病理学分级。将计算的ADC值和动态MR涎腺造影的形态与唇腺活检和Saxon试验结果进行比较。SS患者与健康人的ADC值差异无统计学意义。另一方面，疾病早期患者的ADC值(病灶评分和Lt；2)显著高于正常对照组。在所有SS患者中，动态MR唾液造影显示对酸刺激的反应不足或降低。即使在有早期疾病的患者中，静态MR涎腺造影没有显示明显的形态异常，动态MR唾液造影也显示对酸刺激的异常反应。动态MR唾液管造影结果与Saxon试验结果有显著相关性。我们认为DW磁共振成像和动态MR涎腺造影对发现SS的早期疾病状态是非常有用的。

This study was conducted to assess the utility of diffusion-weighted (DW) MR imaging with use of SPLICE technique and dynamic MR sialography after administration of tartaric acid, and to estimate the salivary gland function in patients with Sjogren syndrome (SS). Imaging parameters of DW MR imaging were: TR=5.9 msec, TE=65 msec, slice thickness=6 mm, gradient factor b= 205.38 and 1496.43 sec/mm^2. The ADC values of the parotid glands were calculated according to the signal intensities in the ROI on DW MR images. Dynamic MR sialography was obtained using a single-shot RARE sequence. Imaging parameters of dynamic MR sialography were: echo spacing=11. 5 msec, effective TE=1100 msec, ETL=240, slab thickness=30 mm. Immediately after intraoral administration of 2-ml of tartaric acid, sequential MR sialograms were obtained for 5 min. The study population was composed of 12 healthy subjects and 54 patients with SS. Labial gland biopsy and Saxon test were performed in all patients. The histopathologic grading was done by means of focus score. Calculated ADC values and morphologic pattern of dynamic MR sialography were compared with the results of labial gland biopsy and Saxon test. As to the ADC values between healthy subjects and patients with SS, no significant difference was observed. On the other hand, the ADC values in patients at early stage of the disease (focus score < 2) were statistically higher than those of healthy subjects. In all patients with SS, lack or reduced response to acid stimulation was seen on dynamic MR sialography. Even in patients with early disease condition in whom static MR sialography showed no significant morphologic abnormalities, dynamic MR sialography showed abnormal response to acid stimulation. Significant correlation was present between the results of dynamic MR sialography and Saxon test. We conclude that DW MR imaging and dynamic MR sialography are extremely useful for detecting the early disease condition of SS.