Mahdi Azizian

Autonomous Image-Guided Robot-Assisted Active Catheter Insertion

Interventional cardiologists are at great risk from radiation exposure due to lengthy procedures performed under X-ray radiations. Angioplasty is one such procedure wherein the clinician guides a catheter into the femoral artery under X-rays and the procedure often extends to over 50 min. A clinician performs several hundred such procedures over his/her lifetime, leading to an accumulation of the total radiation he/she is exposed to. In this paper, we investigate autonomous robot-assisted insertion of an active catheter instrumented with shape memory alloy (SMA) actuators using image guidance. The tip of the active catheter is tracked in real time to provide information on the location of the catheter that determines the optimal stroke length of insertion for the robot and the necessary bending angle for the active catheter. The catheter is autonomously guided from the point of entry to the site of plaque buildup, thereby shielding the clinician from harmful radiation due to the X-rays used for imaging and providing a more ergonomic approach for catheter insertion. Experimental results are given to illustrate the robot-assisted catheter insertion procedure using image guidance.

Stereoscopic augmented reality for laparoscopic surgery

BackgroundConventional laparoscopes provide a flat representation of the three-dimensional (3D) operating field and are incapable of visualizing internal structures located beneath visible organ surfaces. Computed tomography (CT) and magnetic resonance (MR) images are difficult to fuse in real time with laparoscopic views due to the deformable nature of soft-tissue organs. Utilizing emerging camera technology, we have developed a real-time stereoscopic augmented-reality (AR) system for laparoscopic surgery by merging live laparoscopic ultrasound (LUS) with stereoscopic video. The system creates two new visual cues: (1) perception of true depth with improved understanding of 3D spatial relationships among anatomical structures, and (2) visualization of critical internal structures along with a more comprehensive visualization of the operating field.MethodsThe stereoscopic AR system has been designed for near-term clinical translation with seamless integration into the existing surgical workflow. It is composed of a stereoscopic vision system, a LUS system, and an optical tracker. Specialized software processes streams of imaging data from the tracked devices and registers those in real time. The resulting two ultrasound-augmented video streams (one for the left and one for the right eye) give a live stereoscopic AR view of the operating field. The team conducted a series of stereoscopic AR interrogations of the liver, gallbladder, biliary tree, and kidneys in two swine.ResultsThe preclinical studies demonstrated the feasibility of the stereoscopic AR system during in vivo procedures. Major internal structures could be easily identified. The system exhibited unobservable latency with acceptable image-to-video registration accuracy.ConclusionsWe presented the first in vivo use of a complete system with stereoscopic AR visualization capability. This new capability introduces new visual cues and enhances visualization of the surgical anatomy. The system shows promise to improve the precision and expand the capacity of minimally invasive laparoscopic surgeries.

Modeling of a steerable catheter based on beam theory

Catheter-based cardiac ablation is an interventional treatment for heart arrhythmias. Pull-wire steerable catheters are guided to the heart chambers through the vasculature in order to deliver energy to destroy faulty electrical pathways in the heart. The effectiveness of this treatment is dependent on the accuracy of positioning the catheter tip at the target location and also on maintaining contact with the target while the heart is beating. Therefore, it is desirable to perform hybrid force/position control of the catheter tip. We have studied the problem of modeling the distal part of a steerable catheter using beam theory and have developed and validated a static force-deflection model through extensive experiments. It is shown that the model can estimate the shape of the bending section of a catheter using force information and without requiring extensive knowledge of the catheters internal structure.

Visual servoing in medical robotics: a survey. Part I: endoscopic and direct vision imaging – techniques and applications

Intra‐operative imaging is widely used to provide visual feedback to a clinician when he/she performs a procedure. In visual servoing, surgical instruments and parts of tissue/body are tracked by processing the acquired images. This information is then used within a control loop to manoeuvre a robotic manipulator during a procedure.

Image-guided techniques in renal and hepatic interventions

Development of new imaging technologies and advances in computing power have enabled the physicians to perform medical interventions on the basis of high‐quality 3D and/or 4D visualization of the patients organs. Preoperative imaging has been used for planning the surgery, whereas intraoperative imaging has been widely employed to provide visual feedback to a clinician when he or she is performing the procedure. In the past decade, such systems demonstrated great potential in image‐guided minimally invasive procedures on different organs, such as brain, heart, liver and kidneys. This article focuses on image‐guided interventions and surgery in renal and hepatic surgeries.

Cadaveric Feasibility Study of da Vinci Si-Assisted Cochlear Implant With Augmented Visual Navigation for Otologic Surgery

IMPORTANCE To our knowledge, this is the first reported cadaveric feasibility study of a master-slave-assisted cochlear implant procedure in the otolaryngology-head and neck surgery field using the da Vinci Si system (da Vinci Surgical System; Intuitive Surgical, Inc). We describe the surgical workflow adaptations using a minimally invasive system and image guidance integrating intraoperative cone beam computed tomography through augmented reality. OBJECTIVE To test the feasibility of da Vinci Si-assisted cochlear implant surgery with augmented reality, with visualization of critical structures and facilitation with precise cochleostomy for electrode insertion. DESIGN AND SETTING Cadaveric case study of bilateral cochlear implant approaches conducted at Intuitive Surgical Inc, Sunnyvale, California. INTERVENTIONS Bilateral cadaveric mastoidectomies, posterior tympanostomies, and cochleostomies were performed using the da Vinci Si system on a single adult human donor cadaveric specimen. MAIN OUTCOMES AND MEASURES Radiographic confirmation of successful cochleostomies, placement of a phantom cochlear implant wire, and visual confirmation of critical anatomic structures (facial nerve, cochlea, and round window) in augmented stereoendoscopy. RESULTS With a surgical mean time of 160 minutes per side, complete bilateral cochlear implant procedures were successfully performed with no violation of critical structures, notably the facial nerve, chorda tympani, sigmoid sinus, dura, or ossicles. Augmented reality image overlay of the facial nerve, round window position, and basal turn of the cochlea was precise. Postoperative cone beam computed tomography scans confirmed successful placement of the phantom implant electrode array into the basal turn of the cochlea. CONCLUSIONS AND RELEVANCE To our knowledge, this is the first study in the otolaryngology-head and neck surgery literature examining the use of master-slave-assisted cochleostomy with augmented reality for cochlear implants using the da Vinci Si system. The described system for cochleostomy has the potential to improve the surgeons confidence, as well as surgical safety, efficiency, and precision by filtering tremor. The integration of augmented reality may be valuable for surgeons dealing with complex cases of congenital anatomic abnormality, for revision cochlear implant with distorted anatomy and poorly pneumatized mastoids, and as a method of interactive teaching. Further research into the cost-benefit ratio of da Vinci Si-assisted otologic surgery, as well as refinements of the proposed workflow, are required before considering clinical studies.

Autonomous robot-assisted active catheter insertion using image guidance

In this paper, we investigate autonomous robot- assisted insertion of an active catheter instrumented with shape memory alloy (SMA) actuators using image guidance. An Augmented Hybrid Impedance Control (AHIC) algorithm is implemented on a Mitsubishi robot (PA 10-7C) to insert the active catheter. The robot is constrained to move in Cartesian space along a pre-defined trajectory while controlling the force of insertion. A closed-loop control scheme has been developed to accurately control the bending in the active catheter. The tip of the active catheter is tracked in real-time to provide information on the path of the catheter and for determining the future course of insertion. The catheter is autonomously guided from the point of entry to the site of plaque buildup, thereby shielding the surgeon from the harmful radiation due to the X-rays used for imaging, providing a more ergonomic approach for catheter insertion. Experimental results are given to illustrate the robot-assisted catheter insertion procedure.

Bilateral telemanipulation of a flexible catheter in a constrained environment

This paper describes some novel research results on bilateral teleoperation of a flexible catheter in a constrained environment. The dynamics of the catheter in a constrained environment is highly nonlinear and is affected by a large number of factors such as friction, flexibility of the catheter, force of insertion, shape and size of the catheter, etc. As a result, the distal end of the catheter almost never follows the actuated end of the catheter which could cause fatigue to the clinician/user attempting to insert the catheter in a blood vessel. In addition, there is a time delay of up to 0.8 second before the distal end of the catheter advances after the near end is actuated. This delay is sufficient to cause instability in the control loop. We have developed a teleoperation framework using wave variables to perform robot- assisted catheter insertion in a constrained environment while reflecting the forces at the tip of the catheter to the clinician. Experimental results showing the effect of different factors such as the velocity and stroke length of insertion on the delays introduced in control loop and errors between the master and slave position are included. To the best of our knowledge, this work is among the first to attempt to provide an understanding of the effects of various factors on the flexing of the catheter. In addition, master-slave insertion of a catheter instrumented with shape memory alloys (SMA) has also been performed and the results are included in this paper.

Augmented reality and cone beam CT guidance for transoral robotic surgery.

In transoral robotic surgery preoperative image data do not reflect large deformations of the operative workspace from perioperative setup. To address this challenge, in this study we explore image guidance with cone beam computed tomographic angiography to guide the dissection of critical vascular landmarks and resection of base-of-tongue neoplasms with adequate margins for transoral robotic surgery. We identify critical vascular landmarks from perioperative c-arm imaging to augment the stereoscopic view of a da Vinci si robot in addition to incorporating visual feedback from relative tool positions. Experiments resecting base-of-tongue mock tumors were conducted on a series of ex vivo and in vivo animal models comparing the proposed workflow for video augmentation to standard non-augmented practice and alternative, fluoroscopy-based image guidance. Accurate identification of registered augmented critical anatomy during controlled arterial dissection and en bloc mock tumor resection was possible with the augmented reality system. The proposed image-guided robotic system also achieved improved resection ratios of mock tumor margins (1.00) when compared to control scenarios (0.0) and alternative methods of image guidance (0.58). The experimental results show the feasibility of the proposed workflow and advantages of cone beam computed tomography image guidance through video augmentation of the primary stereo endoscopy as compared to control and alternative navigation methods.

Visual servoing in medical robotics: a survey. Part II: tomographic imaging modalities--techniques and applications.

Intraoperative application of tomographic imaging techniques provides a means of visual servoing for objects beneath the surface of organs.