Blood-flow of the TMJ region after MRI examination with wide mouth opening

在对颞下颌关节(TMJ)进行MRI检查时，需要连续张口约10min才能获得张口位的静态图像。由于张开嘴巴而产生的机械和心理压力可能会导致TMJ症状，如肌肉疼痛。采用彩色多谱勒超声检查方法，评价MRJ检查前后TMJ区域的血流情况。测量面部动脉和颞浅动脉的有色区域。同时测量咬肌厚度。结果在MRI检查后，面动脉和颞浅动脉的血流量均减少。MRI检查后，咬肌的平均厚度增加。TMJ的MR图像显示，张开的上颌动脉和面横动脉被张开。在持续张口时，血管的机械拉伸可能会导致血流量的减少。咬肌厚度的增加可能揭示了作为疼痛刺激因素的水肿症。

In the MRI examination of the temporomandibular joint (TMJ), continuous mouth opening about 10 minutes is needed to obtain static images in mouth opening position. The mechanical and psychological stress by the wide and continuous opening of the mouth may cause TMJ symptoms such as muscle pain. To evaluate the blood-flow of the TMJ region in the periods of pre- and post- MRJ examination, color Doppler ultrasonographic examinations were performed. Colored areas indicationg the facial artery and the superficial temporal artery were measured. The thickness of the masseter muscle was also measured. As the results, the blood-flow of the facial artery and the superficial temporal artery were reduced at the post- MRI examination. The mean thickness of the masseter muscle was increased at the post- MRI examination. The findings from MR images of TMJ showed that the maxillaris artery and the transversa faciei artery were stretched by mouth opening. In the continuous mouth opening, the mechanical stretch of the blood vessel may cause the decreasing of blood-flow. The thickness increment of masseter muscle may reveal the oedema which is a provocative factor of the pain