Chiu T-W, Liu Y-J, Chang H-C, Lee Y-H, Lee J-C, Hsu K, Wang C-W, Yang J-M, Hsu H-H, Juan C-J
From the Departments of Radiology (T.-W.C., C.-W.W., H.-H.H., C.-J.J.).
Department of Medicine (T.-W.C.), Taipei Medical University, Taipei, Taiwan.
AJNR Am J Neuroradiol. 2016 Oct;37(10):1909-1915. doi: 10.3174/ajnr.A4852. Epub 2016 Jun 23.
Parotid glands secrete and empty saliva into the oral cavity rapidly after gustatory stimulation. However, the role of the temporal resolution of DWI in investigating parotid gland function remains uncertain. Our aim was to design a high-temporal-resolution echo-planar DWI pulse sequence and to evaluate the instantaneous MR perfusion responses of the parotid glands to gustatory stimulation.
This prospective study enrolled 21 healthy volunteers (M/F = 2:1; mean age, 45.2 ± 12.9 years). All participants underwent echo-planar DWI (total scan time, 304 seconds; temporal resolution, 4 s/scan) on a 1.5T MR imaging scanner. T2WI ( = 0 s/mm) and DWI ( = 200 s/mm) were qualitatively assessed. Signal intensity of the parotid glands on T2WI, DWI, and ADC was quantitatively analyzed. One-way ANOVA with post hoc group comparisons with Bonferroni correction was used for statistical analysis. < .05 was statistically significant.
Almost perfect interobserver agreement was achieved (κ ≥ 0.656). The parotid glands had magnetic susceptibility artifacts in 14.3% (3 of 21) of volunteers during swallowing on DWI but were free from perceptible artifacts at the baseline and at the end of scans on all images. Increased ADC and reduced signal intensity of the parotid glands on T2WI and DWI occurred immediately after oral administration of lemon juice. Maximal signal change of ADC (24.8% ± 10.8%) was significantly higher than that of T2WI (-10.1% ± 5.2%, < .001). The recovery ratio of ADC (100.71% ± 42.34%) was also significantly higher than that of T2WI (22.36% ± 15.54%, < .001).
Instantaneous parotid perfusion responses to gustatory stimulation can be quantified by ADC by using high-temporal-resolution echo-planar DWI.
腮腺在味觉刺激后迅速分泌唾液并排入口腔。然而，扩散加权成像（DWI）的时间分辨率在研究腮腺功能中的作用仍不明确。我们的目的是设计一种高时间分辨率的回波平面DWI脉冲序列，并评估腮腺对味觉刺激的瞬时磁共振灌注反应。
这项前瞻性研究纳入了21名健康志愿者（男/女 = 2:1；平均年龄，45.2±12.9岁）。所有参与者在1.5T磁共振成像扫描仪上接受回波平面DWI检查（总扫描时间，304秒；时间分辨率，4秒/次扫描）。对T2加权成像（T2WI，b = 0秒/毫米²）和DWI（b = 200秒/毫米²）进行定性评估。对腮腺在T2WI、DWI及表观扩散系数（ADC）图上的信号强度进行定量分析。采用单因素方差分析及Bonferroni校正的事后组间比较进行统计分析。P < 0.05具有统计学意义。
观察者间一致性几乎达到完美（κ≥0.656）。在DWI上，14.3%（21例中的3例）的志愿者在吞咽时腮腺出现磁化率伪影，但在所有图像的基线期和扫描结束时均无明显伪影。口服柠檬汁后，腮腺的ADC值立即升高，T2WI和DWI上的信号强度降低。ADC的最大信号变化（24.8%±10.8%）显著高于T2WI（-10.1%±5.2%，P < 0.001）。ADC的恢复率（100.71%±42.34%）也显著高于T2WI（22.36%±15.54%，P < 0.001）。
通过使用高时间分辨率的回波平面DWI，ADC可对腮腺对味觉刺激的瞬时灌注反应进行量化。
