Since its first implementation in otolaryngological surgeries nearly a century ago, the surgical microscope has improved the accuracy and the safety of microsurgeries. However, the microscope only provides a magnified surface view of the surgical region.

Prof. Chulhong Kim’s research team with Department of Creative IT Engineering at Pohang University of Science and Technology (POSTECH) has developed an advanced multimodal imaging system by integrating photoacoustic microscopy, optical coherence tomography, and conventional surgical microscope. Furthermore, they have applied augmented reality techniques in this multimodal imaging system. Their research was recently published in Scientific Report.

The multimodal system provides an enlarged surface view and many subsurface comprehensive biological information, such as tumor margins and blood vessel locations, simultaneously and in real-time. The photoacoustic and optical coherence tomography images are displayed on the ocular lens of the surgical microscope. Since the surgeon can see all three images simultaneously within their immediate field of vision, the safety and accuracy of surgical procedures will be improved.

Prof. Chulhong Kim’s research team demonstrated the feasibility of the multimodal system through simulated surgeries: an in vivo image-guided melanoma resection surgery and an in vivo needle injection of carbon particles into the thigh of a mouse. The system has shown great potential for applications in neurosurgery, ophthalmological surgery, and other microsurgeries.

Additionally, Prof. Chulhong Kim’s research team has developed a high signal-to-noise-ratio (SNR) and fast imaging optical-resolution photoacoustic microscopy (OR-PAM) with a simple and novel OR-PAM technique where a typical galvanometer is immersed in a non-conducting liquid. This research was also published in Scientific Report.

One problem of conventional OR-PAM commercialization is its slow imaging speed. Prof. Chulhong Kim’s research team solved the imaging speed problem while maintaining a high SNR, which takes only 2 seconds to acquire a three dimensional volumetric image with a wide field of view of 4×8 mm² along X and Y axes, and has retained the inherent advantages of ultrasound imaging and optical imaging. The developed technique can noninvasively provide anatomical information (e.g., angiogenesis, vessel structures, melanin distribution, and nerve structures), functional information (e.g., hemoglobin oxygen saturation and blood flow), and metabolic contrast.