Progress We introduced a series of research efforts to advance the intraoperative application of optical coherence imaging. Vascular characteristics are an important basis for intraoperative pathological assessment. We first introduced OCT angiography with adaptive multi-time intervals, which proposes a time-efficient scanning protocol by adaptive optimization of the weights of different time-interval B-scan angiograms. This novel OCTA technique achieved better performance, with a visible vascular density increase of approximately 67% and a signal-to-noise ratio enhancement of approximately 11.6% (Figs. 2 and 3). In the context of intraoperative applications, we introduced robot-assisted OCTA, which integrated a high-resolution OCT system with a 6-degree of freedom robotic arm (Fig. 4). Robot-assisted OCTA can achieve wide-field imaging of artificially determined scanning paths. High-resolution vascular imaging of the mouse brain by robot-assisted OCTA successfully confirmed the effect of unevenly distributed resolution and fall-off caused by the large-curvature sample (Fig. 5). Thereafter, we introduced a microscope-integrated OCT system that can be well integrated with current intraoperative equipment and does not need to pause the surgical process (Figs. 6 and 7). Providing real-time tissue depth information to a doctor can help improve their decision-making ability in delicate surgical procedures such as ophthalmology and nervous system surgery. Intraoperative three-dimensional (3D) real-time imaging requires an OCT system with high imaging and processing speeds. Thereafter, we introduced the 10.3 MHz ultra-high speed scanning laser with stretch pulse mode-locked based on polarization isolation (Fig. 8), which employs a simple and low-cost approach to suppress the transmitted light and achieves an effective duty cycle of ～100% with only one CFBG and no need for intra-cavity semiconductor optical amplifier (SOA) modulation, extra-cavity optical buffering, and post amplification (Fig. 9). Real-time 3D OCT imaging is necessary for practical intraoperative applications, and a series of studies have been conducted to achieve this goal. A home-built 3.28 MHz FDML based OCT system combined with GPUs (NVIDIA, GeForce GTX690, and GeForce GTX680, USA) achieved real-time processing and visualization of 3D OCT data (Fig. 10). The imaging range and longitudinal resolution can be flexibly adjusted by changing the spectral range of the output.
Although OCT offers high-quality structural and vascular imaging, it lacks cellular resolution, which limits detailed tumor analysis. Dynamic full-field OCT (D-FFOCT) is an optically active rapid pathological imaging technology based on array interference detection that captures subcellular metabolic motion at millisecond temporal and nanometer spatial scales, and significantly enhances tumor diagnostics by providing detailed insights beyond conventional OCT capabilities (Fig. 11). Normal and diseased tissues can be accurately distinguished by analyzing the temporal characteristics of dynamic signals, such as amplitude, frequency, and standard difference. Through the use of high-power objective lenses and broadband light sources, the resolution can reach sub-microns, and as an imaging tool for intraoperative tissue sections, it is fast, easy (no freezing or staining is required), and highly accurate. Freshly isolated mouse brain glioma sections were imaged using the D-FFOCT system, which showed a clear boundary, distinct cell structure, and dynamic intensity between the glioma and normal brain tissue (Fig. 12).
Conclusions and Prospects Advancements in OCT technology, including the significantly increased sweep speed of the light source, improvement of the probe for the intraoperative scene, optimization of the blood flow algorithm, and high-speed data processing capability supported by the GPU, make real-time intraoperative 3D tomography possible. D-FFOCT imaging with a cell-resolving ability is an important step forward in the timely pathology of tumor resection. The integration of advanced OCT technologies into clinical practice heralds a new era of precision medicine in which surgical accuracy is significantly enhanced and tumor recurrence is minimized. Future studies should focus on further refining OCT capabilities, integrating these advanced technologies to improve clinical practicability, expanding their applications across different types of cancer, and integrating AI to automate and enhance diagnostic accuracy. This vision foresees OCT not only as a tool for improved surgical interventions but also as a pivotal element in the broader strategy of personalized and targeted treatment approaches, offering a beacon of hope for more effective cancer management and patient recovery paths. The ultimate goal is to establish OCT as an indispensable tool for tumor surgery and management, revolutionizing patient care and outcomes.
Optical coherence tomography (OCT) plays a pivotal role in medical imaging, particularly in enhancing the tumor resection accuracy. The significance of this technology lies in its ability to improve patient prognosis by providing real-time, detailed visualization of tumor boundaries and invasiveness, thereby reducing recurrence rates and aiding the precise removal of malignant tissues.
