Surgical margin analysis (SMA) is an essential procedure in a cancer resection surgery to judge whether all cancer cells are excised from a patient’s body. A positive surgical margin, which means there are still residual cancer cells in the body, could lead to a high recurrence rate. The standard procedure of histological analysis for SMA requires several steps before imaging, including tissue fixation, embedding, sectioning, and staining, which are time-consuming and laborious. Patients are required to undergo second surgeries if a positive surgical margin is found in this post-operative analysis. Therefore, there is a pressing need for a reliable intraoperative tool to eliminate second surgeries.

Ultraviolet photoacoustic microscopy (UV-PAM), which does not require any sample...[ Read more ]

Surgical margin analysis (SMA) is an essential procedure in a cancer resection surgery to judge whether all cancer cells are excised from a patient’s body. A positive surgical margin, which means there are still residual cancer cells in the body, could lead to a high recurrence rate. The standard procedure of histological analysis for SMA requires several steps before imaging, including tissue fixation, embedding, sectioning, and staining, which are time-consuming and laborious. Patients are required to undergo second surgeries if a positive surgical margin is found in this post-operative analysis. Therefore, there is a pressing need for a reliable intraoperative tool to eliminate second surgeries.

Ultraviolet photoacoustic microscopy (UV-PAM), which does not require any sample processing, has recently been developed as a potential imaging tool for intraoperative SMA. However, the imaging speed of UV-PAM should be improved to promote it as a practical intraoperative diagnostic tool. In this thesis, we developed a galvanometer mirror-based UV-PAM (GM-UV-PAM) system for high-speed label-free histology-like imaging. By implementing a one-dimension (1D) galvanometer mirror into our UV-PAM system with a high repetition rate (55 kHz) UV laser, the proposed GM-UV-PAM system can generate subcellular images in less than 15 min over an area of 5 mm × 5 mm, with a lateral resolution of ~1.0 μm.

To demonstrate our GM-UV-PAM system can provide histological analysis for SMA, mouse brain slices with different tissue processing protocols were imaged. The results of imaging thin mouse brain slices show that our GM-UV-PAM images can provide histological information that is consistent with that in standard histological images. For thick tissue sample imaging, the results illustrate that our GM-UV-PAM system can generate high-quality histology-like images for fresh tissue at high speed, which is not achievable in traditional histology.