Feasibility and accuracy of a robotic guidance system for navigated spine surgery in a hybrid operating room: a cadaver study.

The combination of navigation and robotics in spine surgery has the potential to accurately identify and maintain bone entry position and planned trajectory. The goal of this study was to examine the feasibility, accuracy and efficacy of a new robot-guided system for semi-automated, minimally invasive, pedicle screw placement. A custom robotic arm was integrated into a hybrid operating room (OR) equipped with an augmented reality surgical navigation system (ARSN). The robot was mounted on the OR-table and used to assist in placing Jamshidi needles in 113 pedicles in four cadavers. The ARSN system was used for planning screw paths and directing the robot. The robot arm autonomously aligned with the planned screw trajectory, and the surgeon inserted the Jamshidi needle into the pedicle. Accuracy measurements were performed on verification cone beam computed tomographies with the planned paths superimposed. To provide a clinical grading according to the Gertzbein scale, pedicle screw diameters were simulated on the placed Jamshidi needles. A technical accuracy at bone entry point of 0.48 ± 0.44 mm and 0.68 ± 0.58 mm was achieved in the axial and sagittal views, respectively. The corresponding angular errors were 0.94 ± 0.83° and 0.87 ± 0.82°. The accuracy was statistically superior (p < 0.001) to ARSN without robotic assistance. Simulated pedicle screw grading resulted in a clinical accuracy of 100%. This study demonstrates that the use of a semi-automated surgical robot for pedicle screw placement provides an accuracy well above what is clinically acceptable.

Design and control of an image-guided robot for spine surgery in a hybrid OR.

BACKGROUND: Minimally invasive spine (MIS) fusion surgery requires image guidance and expert manual dexterity for a successful, efficient, and accurate pedicle screw placement. Operating room (OR)-integrated robotic solution can provide precise assistance to potentially minimize complication rates and facilitate difficult MIS procedures. METHODS: A 5-degrees of freedom robot was designed specifically for a hybrid OR with integrated surgical navigation for guiding pedicle screw pilot holes. The system automatically aligns an instrument following the surgical plan using only instrument tracking feedback. Contrary to commercially available robotic systems, no tracking markers on the robotic arm are required. The system was evaluated in a cadaver study. RESULTS: The mean targeting error (N = 34) was 1.27±0.57 mm and 1.62±0.85°, with 100% of insertions graded as clinically acceptable. CONCLUSIONS: A fully integrated robotic guidance system, including intra-op imaging, planning, and physical guidance with optimized robot design and control, can improve workflow and provide pedicle screw guidance with less than 2 mm targeting error.

Transperineal prostate intervention: robot for fully automated MR imaging--system description and proof of principle in a canine model.

The study was approved by the animal care and use committee. The purpose of the study was to prospectively establish proof of principle in vivo in canines for a magnetic resonance (MR) imaging-compatible robotic system designed for image-guided prostatic needle intervention. The entire robot is built with nonmagnetic and dielectric materials and in its current configuration is designed to perform fully automated brachytherapy seed placement within a closed MR imager. With a 3.0-T imager, in four dogs the median error for MR imaging-guided needle positioning and seed positioning was 2.02 mm (range, 0.86-3.18 mm) and 2.50 mm (range, 1.45-10.54 mm), respectively. The robotic system is capable of accurate MR imaging-guided prostatic needle intervention within a standard MR imager in vivo in a canine model.

Automatic brachytherapy seed placement under MRI guidance.

The paper presents a robotic method of performing low dose rate prostate brachytherapy under magnetic resonance imaging (MRI) guidance. The design and operation of a fully automated MR compatible seed injector is presented. This is used with the MrBot robot for transperineal percutaneous prostate access. A new image-registration marker and algorithms are also presented. The system is integrated and tested with a 3T MRI scanner. Tests compare three different registration methods, assess the precision of performing automated seed deployment, and use the seeds to assess the accuracy of needle targeting under image guidance. Under the ideal conditions of the in vitro experiments, results show outstanding image-guided needle and seed placement accuracy.

An evaluation method for the mechanical performance of guide-wires and catheters in accessing the upper urinary tract.

The placement of guide-wires and catheters to gain access to the upper urinary tract can induce undesirable stresses on tissues. Previous studies have characterized the performance of wires and catheters by evaluating their physical properties such as stiffness and friction coefficient. However, the results of these studies do not directly quantify the wire's effects on tissues. Furthermore, the individual physical properties of wires and catheters investigated in previous studies cannot be simply summed up to characterize the behavior of an entire wire/catheter ensemble. This paper presents an objective method for testing guide-wires and catheters that estimates the forces applied by these instruments to anatomical structures during urological procedures. Our model utilizes a computer-controlled test stand that simulates a urological environment by including a tortuous path and a stone obstruction. Experimental results using this model show significant promise in reflecting the performance of guide-wires and catheters measuring the stress exerted upon relevant anatomical structures. Furthermore, due to the modularity of the approach, the model can be easily reconfigured to simulate environments relevant to other medical fields.

A New Type of Motor: Pneumatic Step Motor.

This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications.

Robotically assisted prostate brachytherapy with transrectal ultrasound guidance--Phantom experiments.

PURPOSE: To report the preliminary experimental results obtained with a robot-assisted transrectal ultrasound (TRUS)-guided prostate brachytherapy system. METHODS AND MATERIALS: The system consists of a TRUS unit, a spatially coregistered needle insertion robot, and an FDA-approved treatment planning and image-registered implant system. The robot receives each entry/target coordinate pair of the implant plan, inserts a preloaded needle, and then the seeds are deposited. The needles/sources are tracked in TRUS, thus allowing the plan to be updated as the procedure progresses. RESULTS: The first insertion attempt was recorded for each needle, without adjustment. All clinically relevant locations were reached in a prostate phantom. Nonparallel and parallel needle trajectories were demonstrated. Based on TRUS, the average transverse placement error was 2 mm (worst case 2.5 mm, 80% less than 2 mm), and the average sagittal error was 2.5 mm (worst case 5.0 mm, 70% less than 2.5 mm). CONCLUSIONS: The concept and technical viability of robot-assisted brachytherapy were demonstrated in phantoms. The kinematically decoupled robotic assistant device is inherently safe. Overall performance was promising, but further optimization is necessary to prove the possibility of improved dosimetry.

Synthetic torso for training in and evaluation of urologic laparoscopic skills.

BACKGROUND: The expanding use of advanced minimally invasive surgical techniques demands more advanced training methods, objective measures of resident performance, and more realistic and anatomically correct training models. MATERIALS AND METHODS: A new synthetic torso for urologic laparoscopy training was developed and assessed. The trainer, Lapman, was based on the Visible Human Model and has the exact shape of a human torso. The torso models the outer shape of the body and the abdominal and pulmonary cavities. Animal or synthetic models of the abdominal organs may be placed in the abdominal cavity. An abdominal wall provides access and seals the cavity and can be replaced after repeated punctures with laparoscopic instruments. The thoracic cavity connects to a pneumatic pump to simulate breathing. In order to render realistic mechanic properties, the torso is cast of materials with elastic properties similar to those of soft tissue and incorporates a synthetic skeleton. These similar mechanical properties and the thoracic insufflation create realistic ventilatory motion simulation. RESULTS: Twenty-five individuals--medical students, residents, and attending urologists--participated in a study comparing Lapman with a standard training box. Lapman presented several advantages over the traditional training box, specifically with regard to internal and external views and the incorporation of a realistically shaped abdominal wall. A significant and recurrent theme was the value of the synthetic wall as a tool to gain a greater appreciation of the importance of port placement. Study participants at all levels of training appreciated that Lapman gives a more realistic approximation of the operative procedure. CONCLUSIONS: The novelty of the trainer consists in its anatomic shape, realistic mechanical properties, and ventilatory simulation. This paper reports on its design, construction, and preliminary tests.

Technology insight: telementoring and telesurgery in urology.

The rapid expansion of the field of minimally invasive surgery has been accompanied by a number of controversies. These novel surgical techniques offer benefits to the patient with regard to length of hospital stay, return to full activity, and cosmesis; also, they are often more cost-effective than open procedures. On the other hand, they are technically demanding, have a significant learning curve, and can be associated with high initial complication rates unless performed by experienced endoscopic surgeons. Telemedicine, which uses real-time video and information transfer, offers the potential to increase the availability of minimally invasive surgery through video-assisted surgery and through remote instruction. At present, remote communities, especially those within developed countries, can most immediately benefit from telesurgical approaches. Enthusiasm must be tempered by the issues of cost, security, surgeon liability and availability of the technology itself which have yet to be fully resolved. In this Review, the field of telemedicine, focusing specifically on telementoring and telesurgery, and its relevance to urology are discussed. From early experimental work to current clinical usage, the advantages of and problems in this evolving field are explored.

Robotic prostate surgery.

The increasing popularity of robot-assisted radical prostatectomy has put the field of robotics in the spotlight. However, the relationship between medical robotics and the field of urology is older than most urologists know and it will most likely have a bright future beyond any contemporary application. The objective of this review is to provide an insight into the fundamentals of medical robotics and to highlight the history, the present and the future of urological robotic systems with an emphasis on robotic prostate interventions.

A randomized controlled trial of human versus robotic and telerobotic access to the kidney as the first step in percutaneous nephrolithotomy.

OBJECTIVE: We present results from the first randomized controlled trial of human vs. telerobotic access to the kidney during percutaneous nephrolithotomy. METHODS: To compare (a) human with robotic percutaneous needle access and (b) local robotic with trans-Atlantic robotic percutaneous needle access, we used a validated kidney model into which a needle was inserted 304 times. Half the insertions were performed by a robotic arm and the other half by urological surgeons. Order was decided randomly except for a sub-group of 30 trans-Atlantic robotic procedures that were controlled by a team at Johns Hopkins, Baltimore, via four ISDN lines. RESULTS: All attempts were successful within three passes with a median time of 35 s for human attempts compared with a median of 57 s for robotic attempts. The robot was slower than the human to complete insertions (p < 0.001, Mann-Whitney U test), but was more accurate when compared with human operators as it made fewer attempts (88% robotic vs. 79% human first attempt success; p = 0.046, chi-squared test). Times for trans-Atlantic robotic needle insertion (median = 59 s) were comparable to times taken for local robotic needle insertion (median = 56 s) with no difference in accuracy. CONCLUSION: Telerobotics is an accurate and feasible tool for future minimally invasive surgery.

Overview and fundamentals of urologic robot-integrated systems.

Advances in technology have revolutionized urology. Minimally invasive tools now form the core of the urologist's armamentarium. Laparoscopic surgery has become the favored approach for treating many complicated urologic ailments. Surgical robots represent the next evolutionary step in the fruitful man-machine partnership. The introduction of robotic technology in urology changes how urologists learn, teach, plan, and operate. As technology evolves, robots not only will improve performance in minimally invasive procedures, but also enhance other procedures or enable new kinds of operations.

Robotically assisted nerve and facet blocks: a cadaveric study.

RATIONALE AND OBJECTIVES: This study was performed to evaluate the feasibility of using a joystick-controlled robotic needle driver to place a 22-gauge needle for nerve and facet blocks. MATERIALS AND METHODS: Biplane fluoroscopy and a robotic needle driver were used to place 12 needles into the lumbar paraspinal region of an embalmed female cadaver (age at death, 98 years). Small metal BB nipple markers (1 mm in diameter) were inserted percutaneously to serve as targets. Six needles were then placed near the nerve root, and six were placed near the facet root. Anteroposterior and lateral radiographs were obtained after each needle placement to assess its accuracy. RESULTS: All needles were placed within 3 mm of the target BB. The average distance was 1.44 mm +/- 0.66 (standard deviation). DISCUSSION: A robotic needle driver can be used to place needles accurately in the nerve and facet regions. Clinical studies are required to investigate the advantages and disadvantages of this system for interventional procedures involving needles.

System for robotically assisted prostate biopsy and therapy with intraoperative CT guidance.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess the work-in-progress prototype of an image-guided, robotic system for accurate and consistent placement of transperineal needles into the prostate with intraoperative image guidance inside the gantry of a computed tomographic (CT) scanner. MATERIALS AND METHODS: The coach-mounted system consists of a seven-degrees-of-freedom, passive mounting arm: a remote-center-of-motion robot; and a motorized, radiolucent needle-insertion device to deliver 17-18-gauge implant and biopsy needles into the prostate with the transperineal route. The robot is registered to the image space with a stereotactic adapter. The surgeon plans and controls the intervention in the CT scanner room with a desktop computer that receives DICOM images from the CT scanner. The complete system fits in a carry-on suitcase, does not need calibration, and does not utilize vendor-specific features of the CT scanner. RESULTS: In open air, the average accuracy was better than 1 mm at a 5-8-cm depth. In various phantoms, the average orientation error was 1.3 degrees, and the average distance between the needle tip and the target was 2 mm. CONCLUSION: Results of preliminary experiments indicate that this robotic system may be suitable for transperineal needle placement into the prostate and shows potential in a variety of other percutaneous clinical applications.

Telementoring between Brazil and the United States: initial experience.

BACKGROUND AND PURPOSE: To assess the safety and feasibility of transcontinental telementored and telepresence surgery, we report on two procedures carried out with participation by surgeons in Baltimore in the United States and São Paulo and Recife in Brazil. PATIENTS AND METHODS: Over a period of 3 months, a laparoscopic bilateral varicocelectomy and a percutaneous renal access for a percutaneous nephrolithotomy were performed. The mentoring surgeon (LRK) was the same for both procedures. He used a 650-MHz personal computer fitted with a Z360 video COder/ DECoder (CODEC) and a Z208 communication board (Zydacron Corp, Manchester, NH) that comprise the core of the telesurgical station. In the first case, a surgical robot, AESOP 3000 (Computer Motion Inc.), was attached to a laparoscope, and the remote surgeon drove the robot via a controller on the remote computer. In the second case, another robot (Percutaneous Access to the Kidney; PAKY) was used for percutaneous needle placement into the renal collecting system. RESULTS: The two procedures were completed successfully. In the first case, the operative time was 25 minutes, with minimal estimated blood loss. The patient was discharged home the next day. At 3-month follow-up, there was no scrotal pain or varicocele. In the second case, access to the urinary tract was achieved with the first needle pass, and percutaneous nephrolithotomy was uneventful. Blood loss was minimal, and the patient was discharged home on the second postoperative day. At 3-month follow-up, the patient was free of urinary stones and of symptoms. CONCLUSIONS: The first transcontinental telementored and telepresence urologic surgical procedures have been reported previously. The success observed with the novel surgical techniques has motivated great interest. The cases reported here demonstrate that several types of procedures can be mentored safely and effectively with telemedicine technology.

Is telesurgery a new reality? Our experience with laparoscopic and percutaneous procedures.

BACKGROUND: Minimally invasive surgery offers many advantages, but its correct practice is associated with a steep learning curve. Telesurgery allows a surgeon at a remote site to guide and teach surgeons at a primary site by utilizing robotic devices, telecommunications, and video technology, thereby reducing complications. PATIENTS AND METHODS: From September 1998 to July 2000, 17 procedures were telementored between two sites 9230 km apart: a primary operating room at the Policlinico Casilino "Tor Vergata" University of Rome and a remote site at the Johns Hopkins Medical Institutions in Baltimore. Of these procedures, 14 were laparoscopic cases: 8 spermatic vein ligations, 2 retroperitoneal renal biopsies, 3 simple nephrectomies, and 1 pyeloplasty. Three procedures were carried out to obtain percutaneous renal access. All procedures were performed with the help of two robots: the first robot, AESOP, for the orientation of the laparoscope, and the second one, PAKY, to perform the percutaneous renal access. In addition to the robotic device, the system provided four ISDN lines, a PC with dedicated software to manage the connection, audio and video connections, an external video camera with a panoramic view of the operating room, and remote control of the electrocautery and the Telestrator. RESULTS: All the procedures were accomplished with an uneventful postoperative course. Ten operative cases were telementored successfully. In five cases, it was not possible to establish a connection to the remote site, and two procedures were converted to open surgery because of intraoperative complications. The time delay of the image transmission was <1 second. CONCLUSION: This preliminary experience has demonstrated the feasibility of international telementoring. It could provide education to surgeons and decrease the likelihood of complications attributable to inexperience with new techniques.

Robotic percutaneous access to the kidney: comparison with standard manual access.

PURPOSE: To evaluate the efficiency, accuracy, and safety of robotic percutaneous access to the kidney (PAKY) for percutaneous nephrolithotomy in comparison with conventional manual techniques. MATERIALS AND METHODS: We compared the intraoperative access variables (number of access attempts, time to successful access, estimated blood loss, complications) of 23 patients who underwent robotic PAKY with the remote center of motion device (PAKY-RCM) with the same data from a contemporaneous series of 23 patients who underwent conventional manual percutaneous access to the kidney. The PAKY-RCM incorporates a robotic arm and a friction transmission with axial loading system to accurately position and insert a standard 18-gauge needle percutaneously into the kidney. The blood loss during percutaneous access was estimated on a four-point scale (1 = minimal to 4 = large). The color of effluent urine was graded on a four-point scale (1 = clear to 4 = red). RESULTS: The mean target calix width was 13.5 +/- 9.2 mm in the robotic group and 12.2 +/- 4.5 mm in the manual group (P = 0.57). When comparing PAKY-RCM with standard manual techniques, the mean number of attempts was 2.2 +/- 1.6 v 3.2 +/- 2.5 (P = 0.14), time to access was 10.4 +/- 6.5 minutes v 15.1 +/- 8.8 minutes (P = 0.06), estimated blood loss score was 1.3 +/- 0.49 v 1.7 +/- 0.66 (P = 0.14), and color of effluent urine following access was 2.0 +/- 0.90 v 2.1 +/- 0.7 (P = 0.82). The PAKY-RCM was successful in obtaining access in 87% (20 of 23) of cases. The other three patients (13%) required conversion to manual techniques. There were no major intraoperative complications in either group. CONCLUSIONS: Robotic PAKY is a feasible, safe, and efficacious method of obtaining renal access for nephrolithotomy. The number of attempts and time to access were comparable to those of standard manual percutaneous access techniques. These findings provide the groundwork for the development of a completely automated robot-assisted percutaneous renal access device.

A tissue stabilization device for MRI-guided breast biopsy.

We present a breast tissue stabilization device that can be used in magnetic resonance imaging-guided biopsy. The device employs adjustable support plates with an optimized geometry to minimize the biopsy target displacement using smaller compression than the conventional parallel plates approach. It is expected that the reduced compression will cause less patient discomfort and improve image quality by enhancing the contrast intake. Precomputed optimal positions of the stabilization plates for a given biopsy target location are provided in a look-up table. The results of several experiments with a prototype of the device carried out on chicken breast tissue demonstrate the effectiveness of the new design when compared with conventional stabilization methods. The proposed stabilization mechanism provides excellent flexibility in selecting the needle insertion point and can be used in manual as well as robot-assisted biopsy procedures.

A system for laparoscopic surgery ergonomics and skills evaluation.

This article presents a system for tracking, recording, and analysis of instrument and surgeon's arm motion in minimally invasive surgeries. The captured trajectories can be objectively analyzed for both ergonomic assessment and skills evaluation. The system consists of two special infrared (IR) markers that are used for 6 degrees of freedom (DOF) laparoscopic instrument tracking and a set of 3DOF IR markers attached to elbows and shoulders. A compact IR camera tracks and records the markers during a standardized training task (eg, suturing). The instrument markers were purposely designed to provide good tracking while minimizing their volume. The accuracy of the instrument markers was evaluated showing a root mean square error of 0.61 mm, 1.0 mm, and 2.4 mm at distances from the camera of 0.5 m, 0.68 m, and 1 m respectively. Furthermore, some sample trajectories were recorded during an in-trainer suturing task. The Results section presents the values of basic skills metrics computed from the acquired data.

GPU implementation of a deformable 3D image registration algorithm.

We present a parallel implementation of a new deformable image registration algorithm using the Computer Unified Device Architecture (CUDA). The algorithm co-registers preoperative and intraoperative 3-dimensional magnetic resonance (MR) images of a deforming organ. It employs a linear elastic dynamic finite-element model of the deformation and distance measures such as mutual information and sum of squared differences to align volumetric image data sets. Computationally intensive elements of the method such as interpolation, displacement and force calculation are significantly accelerated using a Graphics Processing Unit (GPU). The result of experiments carried out with a realistic breast phantom tissue shows a 37 fold speedup for the GPU-based implementation compared with an optimized CPU-based implementation in high resolution MR image registration. The GPU implementation is capable of registering 512 × 512 × 136 image sets in just over 2 seconds, making it suitable for clinical applications requiring fast and accurate processing of medical images.