University of Illinois researchers have developed a technique to computationally correct for aberrations in optical tomography, which could provide faster, less expensive, higher-resolution tissue imaging to a broader population of users. Real-time, 3D microscopic tissue imaging may be useful for medical fields such as cancer diagnosis, minimally invasive surgery, and, in particular, ophthalmology.
Adaptive optics can correct aberrations in imaging. Widely used in astronomy to correct for distortion as starlight filters through the atmosphere, it works by using a complex system of mirrors to smooth out the scattered light before it enters the lens. Medical scientists have begun applying adaptive optics hardware to microscopes, in hopes of improving cell and tissue imaging.
Unfortunately, hardware-based adaptive optics are complicated, tedious to align, and extremely expensive. They can only focus on one focal plane at a time, so for tomography — 3D models constructed from sectional images as in a CT scan, for example — the mirrors have to be adjusted and a new image scanned for each focal plane. In addition, complex corrective systems are impractical for handheld or portable devices, such as surgical probes or retinal scanners. Instead of using hardware to correct a light profile before it enters the lens, the Illinois team uses computer software to find and correct aberrations after the image is taken. This technique, called computational adaptive optics, was demonstrated in gel-based phantoms laced with microparticles as well as in rat lung tissue.
This technique can be applied to any type of interferometric imaging, such as optical coherence tomography, and the computations can be performed on an ordinary desktop computer. Next, the researchers are working to refine the algorithms and explore applications. They are combining their computational adaptive optics with graphics processors, looking forward to real-time in-vivo applications for surgery, minimally invasive biopsy, and more.