TMJ Fibrocartilage Detection Using 3D Fat-Suppressed Spoiled Gradient-Echo Magnetic Resonance Imaging

Fibrocartilage Signal Intensity

时间窗: six month

Six regions of interest (ROIs) will be measured in the fibrocartilage layer of each TMJ. (anterior 0°, center 45° and posterior 90°), three in the mandibular condyle and three in the temporal fossa. The fibrocartilage signal intensity in each ROI will be expressed as the mean value of intensity units (Osirix). All measurements will be made in a simple blinded system by four different observers (ML, MN, CV, GZ) (chi-square test for interobserver agreement: p˂0.05). Measurements will be made separately in the three MRI sequences (length tool, Osirix Imaging software). In all MRI sequences, TMJ will be magnified at a zoom of 3.6. For the T1 WATS sequence, the window width will be set at 90 intensity Units (IU) (all values above +90 Hounsfield Unit (HU) will be white), and the window level was 80 (IU) (all values below +80 HU will be black). All images will be measured and stored in DICOM format., lengt

Statistical analysis

时间窗: seven months

The Shapiro-Wilk test and Levene's test will be performed to assess normality of data distribution and homogeneity of variance of the measurements, respectively. To determine the relationship between the presence or absence of fibrocartilage and the different sequences, Fisher's exact test will be used. The thickness, length and signal intensity of the fibrocartilage layer will be expressed as a mean value, separated by MRI sequence, and will be analyzed using descriptive statistics. SPSS v14.0 for Windows, statistical software will be used to perform data analysis.

Length of the TMJ fibrocartilage layer

时间窗: Six moths

The lenght of the TMJ FC layer will be measured (curve tool, Osirix) and will expressed in millimeters.

Presence of the TMJ Fibrocartilage layer

时间窗: six months

The fibrocartilage layer will be evaluated dichotomously (absent/present) Patients will be examined using bilateral MRI (Phillips Intera 1,5 T, Sense Flex S Dual Coil) in the sagittal PD-weighted, T2-weighted and T1-weighted WATS, all in the oblique axis of the mandible condyle and with a closed mouth; dynamic gradient-echo at open mouth at 10 mm, 20 mm and 30 mm of the interincisal distance. Additionally, a coronal PD-weighted sequence with the mouth closed will be performed. Of each TMJ will be taken with 8×8 cm FOV and 0.2 cm spacing. All sequences will carried out using the same equipment and on the same day.

Discontinuity of the TMJ FC layer

时间窗: six months

The TMJ fibrocartilage layer will be evaluated dichotomously (continuous/discontinuous).

Thickness of the TMJ fibrocartilage layer

时间窗: Six months

The TMJ FC thickness will be measured (curve tool, Osirix) and will expressed in millimeters.