BME High School Student Program Intern University of Minnesota New Hope, Minnesota, United States
Introduction: Visible Light Polarization Sensitive Optical Coherence Tomography: Polarization Sensitive OCT is a label-free, non-contact, non-invasive imaging method able to capture high-resolution images of cross sections within biological tissue. Visible Light PS-OCT offers an increase in axial resolution and birefringence sensitivity in comparison to infrared PS-OCT [1]. Visible Light PS-OCT is hindered by the noise exhibited by the Supercontinuum Lasers, limiting the SNR Ratio and speed. Testing Balance Detection
Design: Balance Detection is an operation subtracting two out of phase signals to double the signal intensity and remove the noise. Balance detection enhances Visible Light PS-OCT imaging by increasing the Signal to Noise Ratio (SNR) [2].
Materials and
Methods: Materials and Methods would include an image of our Visible Light PS-OCT system, image scan examples of the contrasts, and an image of the mathematical expressions of the contrasts. With the following next to the expressions, *A and Φ denote the amplitude and phase of a complex depth profile, {A1,2(z)exp{iΦ1,2(z)}, along depth z; 1 and 2 correspond to the cross- and co- polarization channels.
Tissue Contrast: Contrasts including reflectivity, cross polarization, and phase retardance are derived from PS-OCT channels.
Results, Conclusions, and Discussions:
Results: Evaluating PS-OCT Enfase Image with Histology The PS-OCT enface image can be validated by comparison with the histology image [3]. The structures are easily identifiable and recognized due to the contrast between the white and gray matter in the PS-OCT image due to the increase birefringence sensitivity. After acknowledging that the structures within the atlas image align, the Visible Light PS-OCT image is accepted as reliable. By taking a closer look in the Thalamus Region of the Mouse Brain, there is an immense difference in the quality and resolution between the PS- OCT enface image and the histology image due to the technology of the Visible Light PS-OCT System.
Results Cont. Cross Sections with and without Balance Detection Visible Light OCT is limited by its susceptibility to noise. Cross sectional images of the Internal Capsule Region of the Macaque Brain are depicted below. Non-balance detection images show a high level of noise. To combat the low SNR, Balance Detection within the Visible Light PS- OCT provides resistance to the noise to create a more favorable image. As Balance Detection is added into the code, it creates a uniform signal. Thus, the data from the cross-sectional images above (I, J, K) is more accessible to create a final high-resolution scan.
Conclusions & Discussions: Visible Light PS-OCT is a credible and proficient approach to the creation of high-resolution brain images. Even without numerical values, it is recognized Balance Detection visibly increases the SNR of the images in the PS-OCT system. Therefore, the details of the structures are better-depicted to produce a quality image. With development, addition of different Balance Detection variety may be implemented to continue to increase signal intensity and completely reduce the noise.
Acknowledgements (Optional): Akkin Lab from the University of Minnesota; PI Taner Akkin Mentor from University of Minnesota - Bahar Baradaran Nirupama Chinthalapati Robbinsdale Armstrong High School
References (Optional): Revin, D. G., Byers, R. A., Duan, M. Q., Li, W. & Matcher, S. J. Visible-light optical coherence tomography platform for the characterization of the skin barrier. Biomed. Opt. Express 14, 3914 (2023). Black, A. J. & Akkin, T. Polarization-based balanced detection for spectral-domain optical coherence tomography. Appl. Opt. 54, 7252 (2015). Allen Institute for Brain Science (2004). Allen Reference Atlas – Mouse Brain [brain atlas]. Available from atlas.brain-map.org.
