Enhancing the signal-to-noise ratio in ophthalmic optical coherence tomography by image registration--method and clinical examples

Optical coherence tomography (OCT) has already proven an important clinical tool for imaging and diagnosing retinal diseases. Concerning the standard commercial ophthalmic OCT systems, speckle noise is a limiting factor with respect to resolving relevant retinal features. We demonstrate successful s...

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Bibliographic Details
Published in:	Journal of biomedical optics Vol. 12; no. 4; p. 041208
Main Authors:	Jørgensen, Thomas Martini, Thomadsen, Jakob, Christensen, Ulrik, Soliman, Wael, Sander, Birgit
Format:	Journal Article
Language:	English
Published:	United States 01-07-2007
Subjects:	Algorithms Humans Image Enhancement - methods Image Interpretation, Computer-Assisted - methods Pattern Recognition, Automated - methods Reproducibility of Results Retina - anatomy & histology Retinal Diseases - pathology Retinoscopy - methods Sensitivity and Specificity Subtraction Technique Tomography, Optical Coherence - methods
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Summary:	Optical coherence tomography (OCT) has already proven an important clinical tool for imaging and diagnosing retinal diseases. Concerning the standard commercial ophthalmic OCT systems, speckle noise is a limiting factor with respect to resolving relevant retinal features. We demonstrate successful suppression of speckle noise from mutually aligning a series of in vivo OCT recordings obtained from the same retinal target using the Stratus system from Humphrey-Zeiss. Our registration technique is able to account for the axial movements experienced during recording as well as small transverse movements of the scan line from one scan to the next. The algorithm is based on a regularized shortest path formulation for a directed graph on a map formed by interimage (B-scan) correlations. The resulting image enhancement typically increases the contrast-to-noise ratio (CNR) with a factor of three or more and facilitates segmentation and quantitative characterization of pathologies. The method is currently successfully being applied by medical doctors in a number of specific retinal case studies.
ISSN:	1083-3668
DOI:	10.1117/1.2772879