Nano-optic endoscope creates high-resolution images of lung cancer tissue
Investigators from the Massachussetts General Hospital and Harvard University recently devised an endoscope capable of producing high-quality and high-resolution images of lung cancer tissue.
The collaboration of experts in endoscopic imaging and flat metalens technology resulted in the invention of a nano-optic cathether that incorporated metalenses into its design. This enabled the acquisition of images with increased quality, resolution and functionality, allowing visualization of fruit flesh, swine and sheep airways and human lung tissue. [Nat Photonics 2018, doi: 10.1038/s41566-018-0224-2]
In the human lung tissue, the researchers were able to identify structures that corresponded to fine, irregular glands indicating the presence of lung adenocarcinoma.
“The versatility and design of the nano-optic endoscope significantly elevates endoscopic imaging capabilities and will likely impact diagnostic imaging of internal organs,” said investigator Dr Hamid Pahlevaninezhad of the Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, US.
“Metalenses are based on flat optics and control of image distortions is straightforward as compared to conventional optics, which requires complex shaped lenses,” explained Professor Federico Capasso of the Harvard University John A. Paulson School of Engineering and Applied Sciences, Boston, Massachusetts, US.
The metalenses at high spatial resolution allows focusing free of spherical aberration and astigmatism, overcoming essential barriers to diffraction-limited focusing and imaging. The technique can be used to achieve high-quality focusing in any complex medium with arbitrary refractive index profile and geometry.
The optical coherence tomography (OCT) catheter is directed and focused into the tissue using a graded-index (GRIN) lens-prism configuration or an angle-polished ball lens. The assembly is encased in a stationary transparent protective sheath. Images are then captured by helically scanning the optical beam within the tissue lumen using distal or proximal actuators.
The researchers are aiming to explore other applications of the nano-optic endoscope in the future. For example, a polarization-sensitive endoscope could provide contrast between tissues with highly organized structures such as smooth muscle, collagen and blood vessels.
“High resolving power is among the most important advantages of optical imaging over other common medical imaging techniques. With the nano-optic endoscope’s high-resolution imaging capabilities with extended depth of focus, it may elevate the capabilities of endoscopic OCT in examining fine pathological changes in luminal tissues,” authors of the study commented.