Angle 78 3 387 - 395

Original Article

Linear Accuracy and Reliability of Cone Beam CT Derived 3-Dimensional Images Constructed Using an Orthodontic Volumetric Rendering Program
Danielle R. Periagoa; William C. Scarfeb; Mazyar Moshiric; James P. Scheetzd; Anibal M. Silveirae; Allan G. Farmanf
ABSTRACT Objective: To compare accuracy of linear measurements made on cone beam computed tomographic (CBCT) derived3-dimensional (3D) surface rendered volumetric images to direct measurements made on human skulls. Materials and Methods: Twenty orthodontic linear measurements between anatomical landmarks on 23 human skulls were measured by observers using a digital caliper. The skulls were imaged with CBCT and Dolphin 3D (version 2.3) software used to generate 3D volumetric reconstructions (3DCBCT). The linearmeasurements between landmarks were computed by a single observer three times and compared to anatomic dimensions using Student’s t-test (P .05). The intraclass correlation coefficient (ICC) and absolute linear and percentage error were calculated. Results: The ICC for 3DCBCT (0.975 0.016) was significantly less than for skull (0.996 0.007) measurements. Mean percentage measurement error for 3DCBCT(2.31% 2.11%) was significantly higher than replicate skull measurements (0.63% 0.51%). Statistical differences between 3DCBCT means and true dimensions were found for all of the midsagittal measurements except Na-A and six of the 12 bilateral measurements. The mean percentage difference between the mean skull and 3D-based linear measurements was 1.13% (SD 1.47%). Ninety percent of mean differences wereless than 2 mm, and 95% confidence intervals were all less than 2 mm except for Ba-ANS (3.32 mm) and Pog-Goleft (2.42 mm). Conclusions: While many linear measurements between cephalometric landmarks on 3D volumetric surface renderings obtained using Dolphin 3D software generated from CBCT datasets may be statistically significantly different from anatomic dimensions, most can be considered to besufficiently clinically accurate for craniofacial analyses. KEY WORDS: Computed tomography; Cone beam; Cephalometry; Diagnostic imaging; Head; 3D CT INTRODUCTION Recently, cone beam computed tomography (CBCT) systems have been developed specifically for the maxillofacial region.1 Many devices are capable of a large field of view imaging of the skull to include most anthropometric landmarks used incephalometric analysis. Time and dose requirements have been suggested to be of the same order of magnitude as other dental radiographic modalities.2 Recently, maxillofacial applications of CBCT imaging have included craniofacial assessment in orthodontics.3–5 High dimensional accuracy has been reported for maxillofacial CBCT in measurement of facial structures.6–9 CBCT derived 3D cephalometry has anumber of potential advantages over conventional CT for cephalometric imaging including submillimeter resolution and reduced radiation exposure, while still permitting reconstruction of the soft tissue profile. Moreover, CBCT datasets can be imported as DICOM files into
387 Angle Orthodontist, Vol 78, No 3, 2008

Graduate student (MS) and resident, Department of Orthodontic and PediatricDentistry, University of Louisville School of Dentistry, Louisville, Ky. b Associate Professor, Department of Surgical/Hospital Dentistry, University of Louisville, Louisville, Ky. c Graduate student (MS) and resident, Department of Orthodontic and Pediatric Dentistry, University of Louisville School of Dentistry, Louisville, Ky. d Professor, Department of Diagnostic Sciences, Prosthetic and RestorativeDentistry, University of Louisville School of Dentistry, Louisville, Ky. e Associate Professor, Department of Orthodontic and Pediatric Dentistry, University of Louisville School of Dentistry, Louisville, Ky. f Professor, Department of Surgical/Hospital Dentistry, University of Louisville, Louisville, Ky. Corresponding author: Dr William Charles Scarfe, Department of Surgical/Hospital Dentistry,...