Detection and significance of the characteristic magnetic resonance signals of mandibular condyles in children

Objective We sought to determine the magnetic resonance imaging (MRI) characteristics of mandibular condyles in still-growing children. In addition, we also evaluated the significance of the double-contour–like structure and the conversion from red to yellow marrow characteristic of this age. Methods The MRI characteristics of mandibular condyles were determined by means of fast spin-echo intermediate-weighted images in subjects 9 to 14 years old. In 1 subject who developed temporomandibular joint–related clinical symptoms 1 year later, MRI was re-performed at that time. Results With the use of MRI, a total of 17 double-contour–like structures were detected in 42 temporomandibular joints of 9- to 14-year-olds, but neither 50 healthy joints of youths nor adults. In terms of bone marrow signal changes, the turning point was found to be 11 years old. In 1 subject, the double-contour–like structures were not visible on the MR images obtained 1 year after the first examination. Conclusion The double-contour–like structure and the periods of conversion from red to yellow marrow may be able to be used as part of the criteria for the staging of mandibular condyle development in children.