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Abstract #47540 Published in IGR 13-4
Variation in optical coherence tomography signal quality as an indicator of retinal nerve fibre layer segmentation error
Folio LS; Wollstein G; Ishikawa H; Bilonick RA; Ling Y; Kagemann L; Noecker RJ; Fujimoto JG; Schuman JSBritish Journal of Ophthalmology 2011;
Purpose: Commercial optical coherence tomography (OCT) systems use global signal quality indices to quantify scan quality. Signal quality can vary throughout a scan, contributing to local retinal nerve fibre layer segmentation errors (SegE). The purpose of this study was to develop an automated method, using local scan quality, to predict SegE. Methods: Good-quality (global signal strength (SS)(greater-than or equal to)6; manufacturer specification) peripapillary circular OCT scans (fast retinal nerve fibre layer scan protocol; Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA) were obtained from 6 healthy, 19 glaucoma-suspect and 43 glaucoma subjects. Scans were grouped based on SegE. Quality index (QI) values were computed for each A-scan using software of our own design. Logistic mixed-effects regression modelling was applied to evaluate SS, global mean and SD of QI, and the probability of SegE. Results: The difference between local mean QI in SegE regions and No-SegE regions was -5.06 (95% CI -6.38 to 3.734) (p<0.001). Using global mean QI, QI SD and their interaction term resulted in the model of best fit (Akaike information criterion=191.8) for predicting SegE. Global mean QI(greater-than or equal to)20 or SS(greater-than or equal to)8 shows little chance for SegE. Once mean QI<20 or SS<8, the probability of SegE increases as QI SD increases. Conclusions: When combined with a signal quality parameter, the variation of signal quality between A-scans provides significant information about the quality of an OCT scan and can be used as a predictor of segmentation error. Copyright Article author (or their employer) 2011.
G. Wollstein. UPMC Eye Center, 203 Lothrop Street, Pittsburgh, PA 15213, USA, . Email: wollsteing@upmc.edu
Classification:
6.9.2.2 Posterior (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.2 Optical coherence tomography)
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
