The Study Of A Navigation System Based On Augmented Reality For Blood Vessel Stereo Location In Microsurgery

Backgroud:With the development of imaging technology,imaging techniques have been applied in angiography,mainly used in the screening and diagnosis of vascular diseases,preoperative evaluation of the occupying lesions,preoperative vascular localization and so on.Among them,preoperative vascular localization helps many surgery,such as microsurgery,locate the blood vessels,which could reduce the difficulty of operation and improve the success rate of operation.However,these techniques can only be used in preoperative design,and the intraoperative blood vessels stereotactic navigation method has been in the blankAugmented reality(AR),as the process of fusing real and synthetic computer-generated images,can project or superimpose a 3D virtual model of target tissues and their complex surroundings reconstructed from a patient's individual CT or MRI data onto real patient images.An AR-based navigation system allows for the visualization of non-apparent structures through overlying tissues to reduce risks and improve success rate of the surgery.The application of augmented reality technology in vascular localization is expected to achieve intraoperative stereo positioning of vessels.Object:This study aimed to combine computed tomographic angiography and augmented reality to build a noval blood vessel stereotaxic technique,and preliminarily establish a naviagtion system suitable for vascular positioning in microsurgery.Analyse the feasibility and accuracy of the naviagtion system.Finally,apply the navigation system in clincal.Methods:1 Research the method for reconstructiong the three-dimensional model of blood vessels and the surrounding structures based on CTA slice images.Analyzing the basic technologies for augmented reality-based navigation system(AR-based NS).After compared advantages and disadvantages of different key techniques for augmented reality,the applicable techniques were selected to establish the AR-based NS for microsurgery.And verifying the feasiblity of the navigation in dog's thoracodorsal artery perforator flap transplantation.2 Perform the AR-basd NS on the RP model,and manually select several pairs of points that could be easily identified on the RP model and projected image for error analysis.Record the coordinates of these pairs of points with the tracking device Micron Tracker,which can be used to detect and calculate the space location through a probe.Then,calculate the distance between the corresponding points to determine the overall system error.3 Patients who underwent extremity reconstruction using anterolateral thigh perforator flap(ALTPF)were selected for analyzing the feasiblity of AR-based NS for clinical application.The preoperative CTA data were imported into 3D platform for preoperation design.The AR-based NS using a marker holder as registration strategy was conducted to realize the intergral image to locate the vessles and guide the dissection of perforator during the operation.Result:1 According to the features of microsurgery,designed and manufactured a screw-fixtion marker holder,and selected video detection system with fiducial marker as registration and tracking technique.And combined with the modeling technique based on CTA data and the display technique based on hemi-transparent helmet,premilinarily established a visual navigation system based on augmented reality for blood vessel stereo positioning in microsurgery.During the dog's thoracodorsal artery perforator flap transplantation surgery,the operative field images were superimposed with the preoperative virtual model to achieve the“seamless”integration images of the virtual and real situation.2 The distance error of the AR-based NS is between1.885mm and 5.544mm,and the average value is 3.474+1.546mm.The average distance error of the detection point 1,2,3 is 4.832±0.617mm,and the average value of the 4,5,6 distance error is 2.116±0.248mm.The precision linearly decreased with the distance from the marker.3 The reconstructed 3D model based on the CTA data can clearly show the relationship between the blood vessel network and the surrounding tissue,and provide a lot of information about the perforator vessels for preoperative design.The application of the AR-based NS makes it possible to observe the intergrated images of the virtual model of the vascular network in the surgical area,and to quickly locate the perforating branches and dissect the perforator precisely.During the operation,the course and the location of perforator were consistent with the navigation information,and its accuracy is higher than preoperative color Doppler ultrasound,and its positioning speed is faster than intraoperative portable B-mode ultrasonography.Conclusion:The registeration and tracking technique based on video detection system with fiducial marker and screw-fixtion marker holder was suitable for the features of microsurgery.The AR-based NS can realize the intraoperative blood vessel stereo positioning,reduce the risk of vascular injury and the difficulty of surgery,increase the success rate of microsurgery.This NS has the feasibility and clinical significance and will have good application prospects.