Projective Imaging And Depth Resolved Fluorescence Imaging In Remote Surgical Navigation

Surgical navigation combines multiple technical advances in medical imaging and computer science.It is playing a more and more important role in modern surgery.However,clinically available surgical navigation systems have not been optimized for telementoring applications,partially due to the poor portability and the lack of the depth resolved surgical guidance.We propose to address these limitations by optical-based projective surgical navigation and depth resolved fluorescence imaging.Our research strategy is to first investigate these two issues separately and then integrate them in a unified unit for telementored surgery applications.The research ideas in this thesis work will stimulate further development and innovation in portable surgical navigation and depth resolved image reconstructions.This paper provides new ideas and references for surgical navigation to overcome distance limitation and near-infrared fluorescence image navigation to provide fluorescence depth information.The main research contents of important research papers are as follows:(1)We developed an interactive remote control and co-axial in projection surgical navigation system for surgery.The co-axial projective imaging module acquires the surgical scene images from the local site of surgery,transfers them wirelessly to the remote site,and projects the instructive annotations to the surgical field.At the remote site,the surgical scene images are displayed,and the instructive annotations from a surgical specialist are wirelessly transferred back to the local site in order to guide the surgical intervention by a less experienced surgeon.The co-axial projective imaging module achieves seamless imaging of the surgical field and accurate projection of the instructive annotations,by a co-axial optical path design that uncouples the imaging arm with the projection arm and by a color correction algorithm that recovers the true color of the surgical scene.Our benchtop study of tele-guided intervention verifies that the proposed system has a positional accuracy better than I mm at a working distance ranging from 300 to 500 mm.Our in vivo study of the resection of melanoma on the skin surface of mice and cricothyrotomy in a rabbit model proves the concept of tele-mentored surgical navigation.This is the first report of tele-guided surgery based on co?axial projective imaging.The proposed technique can be potentially used for surgical training and for telementored surgery in resource-limited settings.(2)We developed a surgical navigation system for depth measurement.The system utilizes fluorescence dual-spectrum imaging to achieve depth measurements from dual-wavelength fluorescence spectroscopy.First,we develop a multifunctional microcapsule contrast agent(MCA)for depth estimation in dual-wavelength fluorescence imaging.The MCA is prepared by encapsulating indocyanine green(ICG),methylene blue(MB)and perfluoropropane(C3F8)in poly(lactic-co-glycolic acid)(PLGA)microcapsules using a modified double-emulsion process.The technical feasibility for MCA-enhanced dual-wavelength fluorescence imaging is tested in tissue-simulating phantoms with various absorption and reduced scattering properties.The MCA depths in the phantoms are reconstructed based on the fluorescence intensity ratios at two different wavelengths and compared with the experimental measurements.Our experimental results indicate that MCA-enhanced dual-wavelength fluorescence imaging is able to estimate the fluorophore depth up to 5 mm at a reconstruction error less than 1 mm.The produced MCA also exhibit hypoechoic characteristic,indicating its technical potential for contrast enhancement in ultrasound/fluorescence dual-modal imaging.