Advances in optical coherence tomography

Optical coherence tomography (OCT) uses light for cross-sectional imaging and is most often used for medical diagnostics, but it also has uses in applications such as analyzing paint on automobiles, non-destructive testing, etc. The global optical coherence tomography market is expected to grow at a CAGR of 15.41% from 2022 to 2030, primarily driven by the demand for its use in diagnosing eye diseases and other disorders. The COVID-19 pandemic has also led to an increase in usage as OCT angiography is used for imaging retinal vascular changes in fully recovered COVID-19 patients.

OCT has progressed in recent years; however, some challenges remain. It is difficult to acquire high resolution OCT images over a wide field of view in all directions, simultaneously. Additionally, OCT images can contain a lot of speckle, caused by random noise.

3D optical coherence tomography refraction

In an attempt to address these issues, researchers at Duke University have developed a new OCT technique called 3D optical coherence refractive tomography (3D OCRT), which produces highly detailed images that would be difficult to observe with traditional OCT.

“We have developed an exciting new extension, featuring new hardware combined with a new 3D image reconstruction computer algorithm to address some well-known limitations in imaging technique,” ​​said Kevin C. Zhou, lead author of the study.

parabolic mirror

What was unique to their setup was that they used a parabolic mirror, which allowed a sample to be imaged from multiple views and a range of angles. They developed an algorithm that combines the views into a single high-quality 3D image that is corrected for noise and other distortions.

“We envision this approach being applied in a wide variety of biomedical imaging applications, such as in vivo diagnostic imaging of the human eye or skin,” said Joseph A. Izatt, co-director of the research team. “The hardware we designed to perform the technique can also be easily miniaturized into small probes or an endoscope to access the gastrointestinal tract and other parts of the body.”

The researchers were able to overcome technical challenges they had faced in previous studies. “Because our system generates tens to hundreds of gigabytes of data, we had to develop a new algorithm based on modern computational tools that have recently matured within the machine learning community,” said Sina Farsiu. , co-leader of the research team.

fruit fly

The researchers imaged biological samples, including a zebrafish, fruit flies (shown here), mice, and more, and were able to acquire 3D fields of view of up to 75 degrees without moving the sample.

“In addition to reducing noise artifacts and correcting sample-induced distortions, OCRT is inherently capable of computer-creating contrast from tissue properties that are less visible in traditional OCT,” said Zhou said. “For example, we show that it is sensitive to oriented structures like fibrous tissues”

Paper: KC Zhou, RP McNabb, R. Qian, S. Degan, A.-H. Dhalla, S. Farsiu, JA Izatt, “Computational 3D microscopy with optical coherence tomography refraction”, 9, 6, 593-601 (2022).
DOI: 10.1364/OPTICA.454860