title: A comparison of methods using optical coherence tomography to detect demineralized regions in teeth.
abstract: Optical coherence tomography (OCT) is a three- dimensional optical imaging technique that can be used to identify areas of early caries formation in dental enamel. The OCT signal at 850 nm back-reflected from sound enamel is attenuated stronger than the signal back-reflected from demineralized regions. To quantify this observation, the OCT signal as a function of depth into the enamel (also known as the A-scan intensity), the histogram of the A-scan intensities and three summary parameters derived from the A-scan are defined and their diagnostic potential compared. A total of 754 OCT A-scans were analyzed. The three summary parameters derived from the A-scans, the OCT attenuation coefficient as well as the mean and standard deviation of the lognormal fit to the histogram of the A-scan ensemble show statistically significant differences (p < 0.01) when comparing parameters from sound enamel and caries. Furthermore, these parameters only show a modest correlation. Based on the area under the curve (AUC) of the receiver operating characteristics (ROC) plot, the OCT attenuation coefficient shows higher discriminatory capacity (AUC = 0.98) compared to the parameters derived from the lognormal fit to the histogram of the A-scan. However, direct analysis of the A-scans or the histogram of A-scan intensities using linear support vector machine classification shows diagnostic discrimination (AUC = 0.96) comparable to that achieved using the attenuation coefficient. These findings suggest that either direct analysis of the A-scan, its intensity histogram or the attenuation coefficient derived from the descending slope of the OCT A-scan have high capacity to discriminate between regions of caries and sound enamel.
authors: National Research Council of Canada, Institute for Biodiagnostics, Winnipeg, MB R3B1Y6, Canada. michael.sowa@nrc-cnrc.gc.ca
authors: Michael G
authors: MG
authors: Sowa
authors: Dan P
authors: DP
authors: Popescu
authors: Jeri R
authors: JR
authors: Friesen
authors: Mark D
authors: MD
authors: Hewko
authors: Lin-P'ing
authors: LP
authors: Choo-Smith
mesh_terms: D019540:Area Under Curve; D001641:Bicuspid / Q000473:pathology; D003198:Computer Simulation; D003731:Dental Caries / Q000175:diagnosis / Q000473:pathology; D003743:Dental Enamel / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D015233:Models, Statistical; D008963:Molar / Q000473:pathology; D009010:Monte Carlo Method; D012372:ROC Curve; D012680:Sensitivity and Specificity; D016008:Statistical Distributions; D018709:Statistics, Nonparametric; D060388:Support Vector Machine; D041623:Tomography, Optical Coherence / Q000379:methods*; D017001:Tooth Demineralization / Q000175:diagnosis* / Q000473:pathology