Optical coherence tomography (OCT) was developed in 1991 by D. Huang, J. Schuman and others at the Massachusetts Institute of Technology. OCT is a low-coherence, interferometer-based, noninvasive medical imaging modality that can provide non-contact, high-resolution, cross-sectional images of biological tissue.
The current global market for OCT systems is around $200 million and is growing at an annual rate of 34%. This expansion is expected to continue at pace for the next several years, with revenues topping $800 million by 2012. See Bio-Medicine.Org, 1-14-2008, at http://www.bio-medicine.org/medicine-news-1/Optical-Coherence-Tomography-Market-to-Top-24800-Million-by-2012-9502-1).
OCT can be divided into many different categories, such as time domain OCT (TD-OCT), time domain OCT with tracking (tracking OCT), polarization-sensitive OCT (PS-OCT), Doppler OCT, spectral domain OCT (SD-OCT), swept source OCT, and adaptive optics OCT. Recently, SD-OCT was commercialized with high resolution and faster acquisition time, compared to conventional TD-OCT such as 2D OCT. The multiple B-scans with SD-OCT provide volumetric data, which can be used to visualize comprehensive structural information, for example, of the retina and retinal pathologies with 3D rendering software in ophthalmology. The capabilities of OCT for quantitative analysis ability are important in this context, especially for glaucoma assessment. Retinal nerve fiber layer (RNFL) thickness measurements, performed via repeated OCT B-scans on the same subject, allow for tracking of developmental changes with glaucoma, which is globally the second leading cause of blindness. Follow-up scans are needed to detect RNFL thickness change, which may take months or years.
There has been no approach available to date that offered the prospect of compatibility between 2D OCT scan and 3D OCT volumetric data. Accordingly, a methodology is needed for establishing compatibility among different devices, by finding the same scan location of a 2D OCT cross-sectional image within follow-up, 3D OCT volumetric data. In particular, clinicians could use such a methodology to track, compare, and ultimately, without inter-device variation, detect any abnormal change that manifests over long periods of time.