Colposcopic imaging using visible-light optical coherence tomography

Abstract

Abstract. High-resolution colposcopic optical coherence tomography (OCT) provides key anatomical measures, such as thickness and minor traumatic injury of vaginal epithelium, of the female reproductive tract noninvasively. This information can be helpful in both fundamental investigations in animal models and disease screenings in humans. We present a fiber-based visible-light OCT and two probe designs for colposcopic application. One probe conducts circular scanning using a DC motor, and the other probe is capable of three-dimensional imaging over a 4.6 × 4.6-mm 2 area using a pair of galvo scanners. Using this colposcopic vis-OCT with both probes, we acquired high-resolution images from whole isolated macaque vaginal samples and identified biopsy lesions.

Spectroscopic imaging with spectral domain visible light optical coherence microscopy in Alzheimer’s disease brain samples

“…Owing to the rather high relative intensity noise of the supercontinuum laser, the system sensitivity was relatively low at 89 dB compared to the use of a standard superluminescent diode operating in the near infrared [ 23 , 42 , 43 ]. Similar sensitivity values were previously reported for visible light OCT systems based on supercontinuum generation [ 20 – 22 , 44 ]. Also there is still some potential in increasing the signal in the short wavelength region, which was limited by the cutoff wavelength of 425 nm for the photonic crystal fiber (NKT Photonics, FD1-PM) currently used for light delivery.…”

Visible-light optical coherence tomography: a review

“…Some early investigations adopted a free-space setup to avoid the excessive loss and imbalanced dispersion in the fiber couplers, 21 , 24 , 25 while those who built line-scan SD vis-OCT could only use a free-space beam splitter and cylindrical lens to illuminate a thin slab of tissue without scanning 15 , 35 . Recently, with improved performance of commercial fiber couplers in the visible spectral range, several groups switched to fiber-based setups to take advantage of the compactness, easy alignment, and easy maintenance 22 , 23 . Since biological tissues have lower laser safety threshold for visible light than NIR light, vis-OCT prefers to adopt an unbalanced splitting ratio (e.g., 10/90 or 30/70) for both free-space and fiber-based Michelson interferometer to maximize the detection efficiency of the backscattered signal from the sample arm 22 , 40 , 41 …”

“…The generally higher scattering coefficients of biological tissue for visible light increase imaging contrast while sacrificing imaging depth. However, when deep penetration is not necessary, similar imaging contrast can be achieved with much lower probing power 23 . In addition to taking advantage of different scattering properties of biological tissues at shorter wavelengths, vis-OCT can also utilize absorption information for quantitative measurement of endogenous chromophore.…”

“…Investigations of vis-OCT have moved from phantom demonstration 34 – 36 to in vivo verification, 25 , 37 from animal experiments 38 , 39 to clinical studies, 22 , 40 , 41 and from technical development 21 , 42 , 43 to pathological investigations of several diseases 44 – 47 Until now, vis-OCT has been applied to imaging different anatomical sites, including the retina, 48 , 49 brain cortex, 50 – 53 and female reproductive tract (FRT) 23 , 54 . Multimodal systems combining vis-OCT with other imaging platforms have been developed to reveal comprehensive information in the examined tissue 40 , 52 , 55 …”

Optical coherence tomography in gynecology: a narrative review

“…A recent paper 21 reports on an OCT system for colposcopy featuring two probe designs. The first design allows for circular scanning while the other is capable of 3-D imaging over a 4.6 × 4.6 mm 2 area.…”