MRI Study Of The Temporomandibular Joint In Young Healthy Volunteers And Chronic Joint Clicking Individuals

Objective:To summarize the MRI anatomic characteristics of the temporomandibular joint (TMJ)in young healthy volunteers, and summarize the MRI anatomical characteristics of the chronic clicking TMJs by comparing the TMJ MRI findings between healthy volunteers and chronic joint clicking individuals.Materials and Methods:60 TMJs in 30 young healthy volunteers(14 males and 16 females) and 20 TMJs in 10 young chronic joint clicking individuals (4 males and 6 females,12 clicking joints)were examined by Phillips 1.5T Achieva MRI scanner. Each joint was scaned by the following orders:opened-and closed-mouth axial T1WI, oblique sagittal and oblique coronal PDWI. The scanning parameters as follows:①TIWI:TR/TE= 550/15msec, FOV=23cm×23cm, NEX=1,Matrix=166288,slice thickness=2mm, no gap.②PDWI:TR/TE=2000/10msec, FOV=13cmxl3cm, NEX=2, Matrix=412×280, slice thickness=3mm, no gap.Results:Observed on different oblique sagittal images, the morphology of the articular disc were different.The ratio of the "double concave" articular disc in the medial, mid and lateral 1/3 levels were 68.33%(41/60),80%(48/60) and 54.24%(32/59), separately; On PDWI, local slightly high signal intensity focus were observed on 28.33%(17/60) articular disc.13 (21.67%,13/60) condyles showed abnormal changes.Joint fluid were observed in all of the 60 joints,85%(51/60) was minimal fluid,15%(9/60) was moderate fluid.On the opened-and closed-mouth images, the display ratio of the anterior superior attachment was 78.83%(47/60) and 88.33(53/60), while the anterior inferior attachment was 15%(9/60) and 20%(12/60).The posterior superior and posterior inferior attachment were displayed clearly in the opened-mouth images, the display ratio was 100%(60/60) and 76.67%(46/60) separately, while not recognized on the closed-mouth images.Some attachment structures were obviously thickened, including 3.33%(2/60) anterior inferior attachment,5%(3/60) anterior superior attachment and 3.33%(2/60) posterior superior attachment.On oblique sagittal images:Some articular discs displaced anteriorly, the ratio of which in the medial, mid and lateral 1/3 levels levels were 35%(21/60),33.33%(20/60) and 47.46%(28/59), separately. There were no significant difference among the "Drace" angles (P>0.05);On oblique coronal images:①The medial margin of the disk exceed that of the condyle in 68.83%(30/47) of the joints in the closed-mouth position, while 95.74%(45/47) in the opened-mouth position; The lateral margin of the disk exceed that of the condyle in 6.38%(3/47) of the joints, the same number in the opened-mouth position.①The distance from the medial margin of the disk to that of the condyle was more farther in the position of opened-mouth than that in closed-mouth(P<0.05);There was no statistically significant difference between the distance from the lateral margin of the disk to that of the condyle in the opened-and closed-mouth position (P>0.05).In the inner 1/3,middle and outer 1/3 levels,the ratio of the non-double concave articular disc in the clicking group was significantly higher than that in the control group(P<0.05);The ratio of anteriorly displacement of the articular disc in the clicking group was higher than that in the control group(P<0.05),and the "Drace" angles were larger than that in the control group(P<0.05);Focal slightly high signal intensity in the articular disc in the clicking group were more common than that in the control group(P<0.05).Abnormal changes of the condyle in the clicking group were more common than that in the control group(P<0.05).In the clicking group, the volume of the joint fluid was larger than that in the control group,58.33%(7/12) of the joint associated with marked fluid.Thickened anterior inferior and anterior superior attachment in the clicking group were more common than that in the control group(P<0.05).Conclusions:Bone and soft tissue anatomical structures and their relationship in the region of TMJ could be clearly displayed on MRI.There were structure variant of the TMJ in young healthy volunteers, which include the articular disc morphology, signal intensity changing, condylar structure abnormality, attachment structure thickening and so on.Observed on the oblique sagittal images, anterior displacement of articular discs may be occured in young healthy volunteers;On the oblique coronal images, some articular discs located medially to the condyle, which were obviously in the opened-mouth position.We could find "undouble concave" articular disc, articular disc with focal slightly high signal intensity, obvious anterior displacement of the articular disc, abnormal condylar changes, marked fluid within articular cavity and thickened anterior inferior and anterior superior attachment commonly in the chronic clicking TMJs.