Three-dimensional cephalometric analysis of adolescents with cleft lip and palate using computed tomography-guided imaging

Reliability of cone beam CT for morphometry of nasolabial soft tissue in patients with skeletal class III malocclusion: A qualitative and quantitative analysis

OBJECTIVE

To assess reliability of cone-beam CT (CBCT) for nasolabial soft tissue measurements in patients with skeletal class III malocclusion based on 3-dimensional (3D) facial scanner results.

METHODS

CBCT and 3D facial scan images of 20 orthognathic patients are used in this study. Eleven soft tissue landmarks and 15 linear and angular measurements are identified and performed. For qualitative evaluation, Shapiro-Wilk test and Bland-Altman plots are applied to analyze the equivalence of the measurements derived from these two kinds of images. To quantify specific deviation of CBCT measurements from facial scanner, the latter is set as a benchmark, and mean absolute difference (MAD) and relative error magnitude (REM) for each variable are also calculated.

RESULTS

Statistically significant differences are observed in regions of nasal base and lower lip vermilion between two methods. MAD value for all length measurements are less than 2 mm and for angular variables < 8°. The average MAD and REM for length measurements are 0.94 mm and 5.64%, and for angular measurements are 2.27° and 3.78%, respectively.

CONCLUSIONS

The soft tissue results measured by CBCT show relatively good reliability and can be used for 3D measurement of soft tissue in the nasolabial region clinically.

Characteristics and dimensions of the infraorbital canal: a radiographic analysis using cone beam computed tomography (CBCT)

PURPOSE

To analyze morphological characteristics and dimensions of the infraorbital canal-groove complex using cone beam computed tomography (CBCT), and to evaluate its relationship with adjacent anatomical structures.

METHODS

This retrospective study included CBCT scans of 100 patients taken between January and May 2014. Linear measurements of the infraorbital canal (IOC), the infraorbital groove (IOG) and the infraorbital canal-groove complex (IOC/G) were performed. Morphological variants of the IOC related to the maxillary sinus were classified into three types depending on the extent of protrusion of the canal into the sinus. Angles between the IOC and specific landmarks were measured to determine the direction of the IOC relative to the axial (A-ant) and sagittal (A-horiz) planes.

RESULTS

A total of 127 IOCs were analyzed. The mean length of the IOC/G was 29 ± 3.0 mm. This value comprised the mean distances of the IOC (24.4 ± 2.9 mm) and the IOG (4.6 ± 1.7 mm). For the different types of IOC morphology, Type 1 (IOC embedded in maxillary sinus roof) was the most common (n = 87, 68.5%). The mean angles of A-ant and A-horiz measured 48.9° ± 7.5° and 20.3° ± 7.9°, respectively.

CONCLUSION

Knowledge of the IOC/G morphology and its variants is important for the prevention of infraorbital nerve injury due to anesthesia or surgical interventions in this area. The presented data of anatomical characteristics of the IOC/G could be helpful for the planning of surgeries in the maxillary region by means of CBCT imaging.

A Novel Three-Dimensional Vector Analysis of Axial Globe Position in Thyroid Eye Disease

Purpose. To define a three-dimensional (3D) vector method to describe the axial globe position in thyroid eye disease (TED). Methods. CT data from 59 patients with TED were collected and 3D images were reconstructed. A reference coordinate system was established, and the coordinates of the corneal apex and the eyeball center were calculated to obtain the globe vector EC→. The measurement reliability was evaluated. The parameters of EC→ were analyzed and compared with the results of two-dimensional (2D) CT measurement, Hertel exophthalmometry, and strabismus tests. Results. The reliability of EC→ measurement was excellent. The difference between EC→ and 2D CT measurement was significant (p = 0.003), and EC→ was more consistent with Hertel exophthalmometry than with 2D CT measurement (p < 0.001). There was no significant difference between EC→ and Hirschberg test, and a strong correlation was found between EC→ and synoptophore test. When one eye had a larger deviation angle than its fellow, its corneal apex shifted in the corresponding direction, but the shift of the eyeball center was not significant. The parameters of EC→ were almost perfectly consistent with the geometrical equation. Conclusions. The establishment of a 3D globe vector is feasible and reliable, and it could provide more information in the axial globe position.