Clearer imaging that cuts through the noise

The next generation of optical coherence tomography (OCT), a common clinical diagnostic imaging method, could see smaller objects more clearly thanks to a modification described in Nature Communications this week. The new method, which can detect structures in the eyes of living mice and on human fingertips that were previously undetectable with conventional OCT, may have potential clinical applications for the early detection of skin cancers and retinal diseases.

A phenomenon called speckle noise, an artefact of imaging with coherent light (beams of photons with the same frequency), has limited the potential of OCT for diagnostic applications. The coherent light scatters and then interferes with itself, making every point in an OCT image randomly appear bright or dark. Previous methods to remove speckle noise have resulted in blurred images and therefore a limited improvement in diagnostic capabilities.

Adam de la Zerda, Orly Liba and colleagues take a new approach to solve this problem. By actively modulating the speckle noise pattern, essentially manipulating the light source used to illuminate samples, the researchers remove the imaging artefact at no cost to resolution. They show that their modified method can detect small structures in the tissues of living animals, such as portions of mouse cornea, fine structures in the mouse ear, and sweat ducts in human fingertip skin that are generally obscured by speckle noise.