Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

• Published in: PloS one Vol. 6; no. 9; p. e24482
• Main Authors: Kashani, Amir H., Kirkman, Erlinda, Martin, Gabriel, Humayun, Mark S.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.09.2011; Public Library of Science (PLoS)
• Subjects: Albinism; Algorithms; Anatomy & physiology; Anesthesia; Animal models; Animals; Architectural engineering; Blood vessels; Calibration; Cameras; Computation; Computed tomography; Data processing; Diabetes mellitus; Diabetic retinopathy; Diabetic Retinopathy - pathology; Diagnostic imaging; Diagnostic systems; Diagnostic Techniques, Ophthalmological; Diffraction patterns; Engineering; Focal plane devices; Glycosylated hemoglobin; Hemoglobin; Hemoglobins - chemistry; Image Processing, Computer-Assisted - methods; Image reconstruction; In vivo methods and tests; Incident light; Medical imaging; Medicine; Microscopy; Models, Statistical; Occlusion; Optics; Optics and Photonics; Oximetry; Oxygen; Oxygen - chemistry; Oxygen - metabolism; Oxygen content; Oxyhemoglobin; Perfusion; Physiology; Rabbits; Reperfusion Injury; Retina; Retinal Vessels - pathology; Retinopathy; Saturation; Spectra; Spectrophotometry - methods; Spectroscopy; Spectrum analysis; Tomography; Tomography, X-Ray Computed - methods; Vascular diseases; Los Angeles California; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024482

Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10-15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology.