A co-registered multimodal imaging system for reflectance, multiphoton, and optical coherence microscopy

Abstract

Multimodal imaging is an advantageous method to increase the accuracy of disease classification. As an example, we and others have shown that optical coherence tomography images and fluorescence spectroscopy contain complementary information that can increase the sensitivity and specificity for cancer detection. A common challenge in multimodal imaging is image co-registration. The different images are often taken with separate imaging setups, making it challenging to precisely image the same tissue area or co-register the images computationally. To solve this problem, we have developed a co-registered multimodal imaging system that images the same tissue location with reflectance, multi-photon, and optical coherence microscopy. The co-registration mechanism is a dual-clad fiber that integrates with a scanning microscope or scanning endoscope, collecting all three signals using the same optical path. In the current implementation, optical coherence tomography utilizes a 1300 nm super luminescent diode, multi-photon signals are excited by a custom femtosecond 1400 nm fiber laser producing two-and three-photon signals in the 460-900 nm band, and reflectance imaging operates at 561 nm. The system separates the different signals using fiber wavelength division multiplexers, a dual-clad fiber coupler, and dichroic mirrors to deliver the different signals to the corresponding detector. This wavelength selection enables the system to work passively, meaning that there is no need for devices such as filter wheels. Using the scanning microscope configuration, we have obtained multimodal images of ex-vivo ovine ovary tissue. © 2021 SPIE.