Volumetric differences in the temporomandibular joint in patients with condylar hyperplasia in active and passive state, SPECT/CT study.

Aim: Condylar hyperplasia (CH) is a progressive and deforming disease that modifies anatomy of the temporomandibular joint (TMJ) structures. This study aims to correlate the metabolic bone activity of the condyle measured by SPECT with the volumetry anatomic information from the condyle, fossa and joint space provided by CT images, in patients with CH in active and inactive forms.

Materials and methods: A cross-sectional comparative study was performed with a set of 116 images from healthy and diagnosed CH patients to compare volumetric measures of the TMJ. Images were acquired through a bone tissue mask using a three-dimensional DICOM reconstruction for SPECT/CT and CBCT images and the Threshold option for segmentation with standardized values for each tissue on the HU scale.

Results: there are differences (p<0.01), with greater condylar volume on the affected side in patients with active CH compared to passive CH. The volume of the glenoid cavity shows no differences in either form of CH (p>0.05), however, there were differences for the volume of the joint space on the affected right side of hemimandibular elongation (HE) in the active form. The volume of the mandibular condyle on the affected side in CH cases were larger in HE cases in active and inactive form (p<0.01) compared to healthy patients. Similar results were presented for the glenoid cavity and joint space.

Conclusions: Volumetric anatomical evaluation of TMJ structures, as well as information on condylar metabolic activity, can be obtained from SPECT/CT. The study shows a greater condylar volume on the affected side of the CH compared to the contralateral side, but there are more significant differences in the active than in the inactive form.