Current cervical screening techniques are fairly effective at assessing the ectocervical surface, but they are limited in their capacity to assess the endocervical canal. There is a need for tools that examine the endocervical canal for cancerous or pre-cancerous lesions. This pilot study explores whether an endoscopic imaging approach combining structural and functional imaging techniques (optical coherence tomography (OCT) and autofluorescence imaging (AFI) respectively) can visualize cancerous or pre-cancerous changes in the endocervical canal. We present findings from an on-going in vivo imaging study including sample cases demonstrating precancers and cancers and preliminary features of interest.
Cervical cancer continues to be among the most frequently diagnosed and fatal cancers among women, ranking fourth in both categories globally in 2018. Detecting and treating early signs of cervical cancer drastically improves patient survivability. We will present images of the inner endocervical canal and the ectocervix taken by a fiber-based imaging system capable of co-registered Optical Coherence Tomography (OCT) and Autofluorescence Imaging (AFI). The rotary-pullback double clad fiber (DCF) imaging catheter captures 3D volumetric OCT scans and 2D AFI surface maps from within the endocervix. Images are obtained from patients undergoing colposcopy-guided biopsies or Loop Electrosurgical Excision Procedure (LEEP).
KEYWORDS: Reflectivity, Imaging systems, RGB color model, Optical coherence tomography, Endoscopes, Fiber optics, Endoscopy, Signal to noise ratio, Tongue, In vivo imaging
A fiber-based endoscopic imaging system combining narrowband red-green-blue (RGB) reflectance with optical coherence tomography (OCT) and autofluorescence imaging (AFI) has been developed. The system uses a submillimeter diameter rotary-pullback double-clad fiber imaging catheter for sample illumination and detection. The imaging capabilities of each modality are presented and demonstrated with images of a multicolored card, fingerprints, and tongue mucosa. Broadband imaging, which was done to compare with narrowband sources, revealed better contrast but worse color consistency compared with narrowband RGB reflectance. The measured resolution of the endoscopic system is 25 μm in both the rotary direction and the pullback direction. OCT can be performed simultaneously with either narrowband RGB reflectance imaging or AFI.
KEYWORDS: Endoscopes, RGB color model, In vivo imaging, Fiber optics, Cancer, Signal to noise ratio, Oncology, Imaging systems, Prototyping, Image resolution
The early detection of cancer brings increased success in the treatment of cancer patients. A prototype sub-millimeter diameter high resolution fibre endoscope for the in-vivo imaging in oral, lung, cervix, ovarian and pancreas sites for the early detection and delineation of cancers is currently in its early stages of development. The endoscope is to utilize a combination of rotary and pullback motion to allow a wide field-of-view while capturing high-resolution (10 to 20 um) RGB images. In this system an RGB laser module uses the core of a dual-clad fibre for illumination and the inner cladding for detection to achieve real time in-vivo reflectance imaging .
Signal detection for each laser (RGB) has been tested using a white card printed with black lines of varying widths. The contrast between the white and black portions of the card and the Signal to Noise Ratio (SNR) for the pullback mechanism of the system were determined. The card contrast values for red, green and blue light were calculated to be 25.0, 15.6 and 8.3 respectively, while the SNR values were 180, 155, and 154 respectively. These values suggest that the performance of the system is wavelength dependent. The imaging performance characteristics of the endoscope with rotary and pullback motion combined will be further quantified, and results and images will be presented.
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