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Optical coherence tomography angiography (OCTA) can provide rapid, volumetric, and noninvasive imaging of tissue microvasculature without the requirement of exogenous contrast agents. To investigate how A-scan rate and interscan time affected the contrast and dynamic range of OCTA, we developed a 1.06-µm swept-source OCT system enabling 100-kHz or 200-kHz OCT using two light sources. After system settings were carefully adjusted, almost the same detection sensitivity was achieved between the 100-kHz and 200-kHz modalities. OCTA of ear skin was performed on five mice. We used the variable interscan time analysis algorithm (VISTA) and the designated scanning protocol with OCTA images reconstructed through the correlation mapping method. With a relatively long interscan time (e.g., 12.5 ms vs. 6.25 ms for 200-kHz OCT), OCTA can identify more intricate microvascular networks. OCTA image sets with the same interscan time (e.g., 12.5 ms) were compared. OCTA images acquired with a 100-kHz A-scan rate showed finer microvasculature than did other imaging modalities. We performed quantitative analysis on the contrast from OCTA images reconstructed with different A-scan rates and interscan time intervals in terms of vessel area, total vessel length, and junction density.

Recently, the functional extension of optical coherence tomography (OCT) with OCT angiography (OCTA) allows volumetric imaging of the subsurface microvasculature without requiring exogenous contrast agents like conventional angiography techniques. However, performing OCTA requires intensive computation to extract the changes of OCT signal due to moving red blood cells in the microvascular network. In this study, we have developed a graphic processing unit (GPU)-accelerated framework to realize high speed OCTA imaging and the visualization of the microvascular network after the data acquisition. In addition, we investigate the feasibility of providing real-time microvascular imaging leveraging dynamic scattering OCT and GPU.

Fourier-domain optical coherence tomography (FD-OCT), including spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT), allows the volumetric imaging of the tissue architecture with a faster speed and higher detection sensitivity than does time-domain OCT. Although the hardware implementations of SD-OCT and SS-OCT are different, these technologies share very similar signal processing steps for image reconstruction. In this study, we developed hardware implementations and software architectures to design a generic framework for FD-OCT. For SD-OCT systems, an external synchronization approach was used to realize a data acquisition schematic similar to that used in SS-OCT by carefully managing the timing clocks in the detection unit and for the waveform generation. In addition, by utilizing modules and factory concepts, a software engine can be developed that supports various acquisition devices and software operations or image processing functions with high operation flexibility while maintaining its robustness. Data processing and data saving were optimized using the parallel computing method with the OpenMP library and by leveraging the parallelism within the acquired data, respectively.

Currently, the cochlear implantation procedure mainly relies on using a hand lens or surgical microscope, where the success rate and surgery time strongly depend on the surgeon’s experience. Therefore, a real-time image guidance tool may facilitate the implantation procedure. In this study, we performed a systematic and quantitative analysis on the optical characterization of ex vivo mouse cochlear samples using two swept-source optical coherence tomography (OCT) systems operating at the 1.06-µm and 1.3-µm wavelengths. The analysis results demonstrated that the 1.06-µm OCT imaging system performed better than the 1.3-µm OCT imaging system in terms of the image contrast between the cochlear conduits and the neighboring cochlear bony wall structure. However, the 1.3-µm OCT imaging system allowed for greater imaging depth of the cochlear samples because of decreased tissue scattering. In addition, we have investigated the feasibility of identifying the electrode of the cochlear implant within the ex vivo cochlear sample with the 1.06-µm OCT imaging. The study results demonstrated the potential of developing an image guidance tool for the cochlea implantation procedure as well as other otorhinolaryngology applications.

Oral cancer was ranked as the fifth most common cancers in both sexes in Taiwan in 2014. For patients diagnosed with the advanced or late stage of oral SCC, the five-year survival rate is reported to be ~ 33% suggesting the importance of the early detection of oral cancer. There have been various studies of investigating the clinical utility of OCT for the early detection of oral precancerous lesions with 1300 nm OCT technology. In this study, we have developed a long-wavelength, multiscale OCT imaging system enabling multiscale imaging of the ex vivo oral precancerous tissue with an increased imaging depth. Objectives with two different magnifications are mounted to a power turret, enabling seamless change of the OCT imaging resolution via the software control. OCT imaging over a variety of oral precancer pathologies will be demonstrated with above OCT system.

We developed a software architecture utilizing the MFC library, allowing OCT imaging/data acquisition in a synchronized fashion. This architecture supports both version of the Fourier-domain OCT frameworks, including the spectral-domain and the swept-source OCT.