Abstract
Abstract: :
Purpose: To demonstrate the new technology based on fast spectral–domain optical coherence tomography for simultaneous acquisition of the sectional and fundus intensity images, which solved the problem of precise spatial registration of OCT sectional images with fundus landmarks. To demonstrate the application of fast spectral–domain OCT in mapping retinal volumes and pathologies in vivo. Methods: A high–speed spectral–domain ophthalmic optical coherence tomography (OCT) system was built for clinical applications with spatial resolution better than 8 µm. Three dimensional OCT image data set consisting of 65536 A–scans can be acquired in less than 2.3 seconds. An algorithm was developed to extracting the en face fundus intensity image that is similar to the intensity image produced by a scanning laser ophthalmoscope (SLO) from the same spectra that were used for generating the OCT sectional images. This function offers perfect spatial registration between the sectional OCT images and the fundus image, which is desired in ophthalmology for monitoring data quality, locating pathology, and increasing reproducibility. Three–dimensional information was extracted through image segmentation and was used to map the retinal volumes and pathologies. Algorithms were developed to peel off the retina layer by layer to construct fundus images of the sub–retinal regions of interest. Results: Both normal and diseased human eyes were imaged with our system. High quality fundus images were acquired from the same OCT data set. Videos were generated showing the exact spatial location for each OCT sectional image. Retinal thickness and volume maps were generated for normal and diseased eyes. The quality of the sub–retinal fundus images is very similar to that of angiography. Conclusions: We have developed a technique to acquire a SLO quality fundus intensity image from the raw spectra measured with spectral–domain OCT, the same spectra used to generate a 3D OCT data set. This technique offers simultaneous fundus and OCT images and, therefore, solves the problem of registering a cross–sectional OCT image to fundus features. Because the fundus image is generated from the measured raw spectra, it can be displayed quickly, possibly in real time. The techniques presented here were successfully demonstrated with a high–speed spectral–domain OCT system on human retina in vivo. The sub–retinal fundus image can be used to provide high contrast images of the blood vessels to align the OCT data set to images from other imaging modalities.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • age-related macular degeneration