Application of cephalometric measurements in 3D-TC

Patrícia de Medeiros Loureiro LOPES, Andréia PERRELLA, Carla Ruffeil MOREIRA, José Rino NETO, Marcelo Gusmão Paraiso CAVALCANTI

Aim: To test the precision and accuracy of conventional linear cephalometric measurements in 3D reconstructed images using a multislice CT. Methods: The study population consisted of 10 dry skulls, previously selected, without distinction of ethnic group and sex, which were submitted to a multislice CT 16 slices using 0.5mm of slice thickness and 0.3mm of interval of reconstruction. Subsequently the data was sent to an independent workstation. Conventional craniofacial landmarks (n=13), usually applied to facial orthopedic and orthodontic treatment planning, were localized and linear measurements (n=15) were obtained by 2 radiologists, twice each, independently, in 3D-CT images. In total 600 measurements were made. The correspondent physical measurements were obtained by a third examiner using a digital caliper. Statistical evaluation of the measurements was carried out regarding to inter and intra-examiner, in 3D-CT, and between image and physical measurements from dry skulls, using analysis of variance. Results and Conclusions: There were no statistically significant differences between inter and intra-examiner measurements or between imaging and physical measurements. The results also showed an inter-examiner variability error of 2.05%, and an intra-examiner variability error of 2.11%. There were also no statistically significant differences between imaging and physical measurements with p>0.6 for all measurements. The mean difference was from 0.96% to 1.47% for all measurements. The validity of linear cephalometric measurements was established using 3D volume rendering from a multislice CT with high precision and accuracy.

Keywords: Cephalometry. Computed tomography. 3D-CT.

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