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New UW Bioengineering faculty member Ricky Wang using light rays to image hard-to-reach structures in the body
The biggest advances in biomedical imaging have taken us deep into tissue, giving new pictures of areas of the body that had been difficult or impossible for scientists and clinicians to see. A new imaging method being studied by UW Bioengineering faculty member Ruikang “Ricky” Wang could continue in this tradition by giving us pictures of such hard-to-reach areas as blood vessels in the retina and hair cells inside the cochlea. In this method of imaging, optical coherence tomography, a ray of light is shone through the body to reach these inaccessible tissues and provide a picture of them. “We’re using light to see through the body, just like X-rays but light is safe, so you can see through tissues without harming the body,” explained Wang, a researcher in the area of biomedical imaging who joined the UW last year.
Optical coherence tomography relies on detecting the back-scattering of the light that shines into the body. An instrument measures shifts in the light that returns from the tissue, and computer analysis of that signal gives an image of the structures in that tissue. Wang is currently applying this imaging technique to take pictures of the detailed vasculature of the retina, which is an important site of analysis in age-related macular degeneration, a leading cause of vision impairment.
“Previously, the eye was imaged with a fundus camera, a sort of microscope that just gives information about the surface of the retina,” Wang said. “That means we can’t see what is going on in the depths of eye tissue. We can use this new method to see right through the retina and see the vasculatures inside it.”
In macular degeneration, one sign of the advancement of the disease is the growth of new vasculature deep inside the retina and choroid, but older methods of retinal imaging have struggled to see this activity. When clinicians are treating macular degeneration with drugs that inhibit vasculature growth, Wang explained, they have not been able to directly monitor the drug’s effectiveness. If this method pans out, clinicians will have a much better way to analyze whether these treatments are having the desired effect. Wang is collaborating on this project with two colleagues in the UW Department of Ophthalmology, Tueng Shen, associate professor, and Russell Van Gelder, chair of ophthalmology. Their research so far has relied on human volunteers, and they are pursuing approval for taking the imaging technique into the clinic for further testing.
Wang and his colleagues are also working on applying optical coherence tomography to studying hair cells, the tiny structures in the cochlea that play an important role in hearing. When sound waves enter the ear, the hair cells vibrate, and that movement then helps send an auditory signal to the brain. Scientists have found it incredibly difficult to study hair cells, though, since they are microscopic in size, reside deep inside the inner ear, and only move about one nanometer when hit with sound waves.
Because of these difficulties in studying hair cells, researchers do not know much about how the cells move in response to sounds, and the actual mechanism for translating hair cell movement into auditory signals in live mammals. For this project, Wang and his colleagues are studying mammal models of the ear, and their technique will involve making a very small hole in the eardrum, inserting a catheter through the hole and reaching the cochlea. The catheter would then shine a light through the cochlea, picking up backscatter of light when the hair cells move—hopefully giving the researchers a detailed picture of how the cells respond to sound waves, in addition to a picture of vasculature that innervates the cochlea.
The project, funded by the National Institute for Deafness and Other Communication Disorders, is in its early stages now, and it will be a while before this technique is tested in humans, Wang said. But if the researchers are successful, their work could play an important role in understanding the mechanisms of hearing.
“This could improve our understanding of the process of hearing, and potentially sudden sensorineural hearing loss,” Wang said. “This could also have a big impact on hearing implants—if you understand the mechanism of the inner ear better, you could improve devices that augment or replace those structures.”
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