Sella Turcica Area and Location of Point Sella in Cephalograms Acquired with Simulated Patient Head Movements.

AIM AND OBJECTIVE

This study assesses changes in the sella turcica area (STA) and location of the cephalometric point sella (S) on lateral cephalograms acquired by charge-coupled device (CCD)-based cephalostats with and without simulated patient head movements.

MATERIALS AND METHODS

A real skull was placed on a robot, able to simulate four head movements (anteroposterior translation/lifting/nodding/lateral rotation) at three distances (0.75/1.5/3 mm) and two patterns (returning to 0.5 mm away from the start position/staying at maximum movement excursion). Two ProMax-2D cephalostats (Dimax-3, D-3 or Dimax-4, D-4), and an Orthophos-SL cephalostat (ORT) acquired cephalograms during the predetermined movements ("cases," 48 images/unit) and without movement ("controls," 24 images/unit). Three observers manually traced the contour of sella turcica and marked point sella using a computer mouse. STA was calculated in pixels by dedicated software based on the tracing. S was defined by its and coordinates recorded by the same software in pixels. Ten percent of the images were assessed twice. The difference between cases and controls (case control) for the STA and S (namely Diff-STA and Diff-S) was calculated and assessed through descriptive statistics.

RESULTS

Inter- and intraobserver agreement ranged from moderate to good for STA and S. Diff-STA ranged from -42.5 to 12.9% (D-3), -15.3 to 9.6% (D-4), and -25.3 to 39.9% (ORT). Diff-S was represented up to 50% (D-3), 134% (D-4), and 103% (ORT) of the mean sella turcica diameter in control images.

CONCLUSION

Simulated head movements caused significant distortion in lateral cephalograms acquired by CCD-based cephalostats, as seen from STA and S alterations, depending on the cephalostat.

CLINICAL SIGNIFICANCE

Patient-related errors, including patient motion artifacts, are influential factors for the reliability of cephalometric tracing.