Signal-to-background ratio and lateral resolution in deep tissue imaging by optical coherence microscopy in the 1700 nm spectral band

Abstract

We quantitatively investigated the image quality in deep tissue imaging with optical coherence microscopy (OCM) in the 1700 nm spectral band, in terms of the signal-to-background ratio (SBR) and lateral resolution. In this work, to demonstrate the benefits of using the 1700 nm spectral band for OCM imaging of brain samples, we compared the imaging quality of OCM en-face images obtained at the same position by using a hybrid 1300 nm/1700 nm spectral domain (SD) OCM system with shared sample and reference arms. By observing a reflective resolution test target through a 1.5 mm-thick tissue phantom, which had a similar scattering coefficient to brain cortex tissue, we confirmed that 1700 nm OCM achieved an SBR about 6-times higher than 1300 nm OCM, although the lateral resolution of the both OCMs was similarly degraded with the increase of the imaging depth. Finally, we also demonstrated high-contrast deep tissue imaging of a mouse brain at a depth up to 1.8 mm by using high-resolution 1700 nm SD-OCM.

1700 nm optical coherence microscopy enables minimally invasive, label-free, in vivo optical biopsy deep in the mouse brain

“…With this goal in mind, here we design and demonstrate the first OCM system for in vivo imaging of brain cellular architecture in the 1700 nm optical window, where ballistic attenuation in the brain is minimal 11,[16][17][18][19] . Technical challenges of this emerging wavelength range are addressed through the system design, including the choice of light source, dispersion compensation method, and optical components.…”

Surface-Enhanced Raman Scattering Bioimaging with an Ultrahigh Signal-to-Background Ratio under Ambient Light

“…The intraoperative image-guided cancer surgery and sentinel lymph node (SLN) identification have garnered much attention in clinics with the ability of real-time, accurate, and visualized localization of potential lesions. − The advances in image-guided surgery studies, either on animal models or patients, raised the demand of a molecular imaging modality that provides high image contrast . This is usually assessed by the image signal-to-background ratio (SBR), defined as the level of desired signals compared to that of the background. − Additionally, intraoperative bioimaging is typically acquired in a dark environment to avoid the background interference from ambient light such as the illumination source and cell phones . However, a dark environment brings inconvenience for the surgeon, for example, to precisely locate the target.…”

Quantum optical tomography based on time-resolved and mode-selective single-photon detection by femtosecond up-conversion

“…Therefore, the spectral window of 1550 -1800 nm referred to as NIR Window III or "golden window" would provide optimal performance for enhancing image contrast at larger penetration depths. In fact, OCT in the 1700-nm spectral band has been developed in the last few years [6][7][8] .Besides the scattering and absorption losses, the phenomenon of multiple scattering also makes it difficult to achieve meaningful structural information at deeper penetration depths 9 . The fraction of multiply scattered photons that contributes to the OCT image increases with the depth in the specimen, resulting in reduced signal…”

“…Therefore, the spectral window of 1550 -1800 nm referred to as NIR Window III or "golden window" would provide optimal performance for enhancing image contrast at larger penetration depths. In fact, OCT in the 1700-nm spectral band has been developed in the last few years [6][7][8] .…”