Alexandru Patriciu

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.

“MRI Stealth” robot for prostate interventions

The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep 4, designed for the robot reported here with uncompromised MRI compatibility, high‐precision, and medical safety. MrBot is one of the “MRI stealth” robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi‐imager compatible, being able to operate with the imager of choice or cross‐imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light‐based encoding is used for feedback, so that all electric components are distally located outside the imagers room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in‐scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low‐dose radiation seed brachytherapy. This paper gives an introduction to the challenges of MRI robot compatibility and presents the solutions adopted in making the MrBot. Its multi‐imager compatibility and other preclinical tests are included. The robot shows the technical feasibility of MRI‐guided prostate interventions, yet its clinical utility is still to be determined.

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

AcuBot: a robot for radiological interventions

We report the development of a robot for radiological percutaneous interventions using uniplanar fluoroscopy, biplanar fluoroscopy, or computed tomography (CT) for needle biopsy, radio frequency ablation, cryotherapy, and other needle procedures. AcuBot is a compact six-degree-of-freedom robot for manipulating a needle or other slender surgical instrument in the confined space of the imager without inducing image artifacts. Its distinctive characteristic is its decoupled motion capability correlated to the positioning, orientation, and instrument insertion steps of the percutaneous intervention. This approach allows each step of the intervention to be performed using a separate mechanism of the robot. One major advantage of this kinematic approach is patient safety. The first feasibility experiment performed with the robot, a cadaver study of perispinal blocks under biplanar fluoroscopy, is presented. The main expected application of this system is to CT-based procedures. AcuBot has received Food and Drug Administration clearance (IDE G010331/S1), and a clinical trial of using the robot for perispinal nerve and facet blocks is presently underway at Georgetown University, Washington, DC.

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.

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.

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.

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.

Motion-Based Robotic Instrument Targeting under C-Arm Fluoroscopy

We present a simple and precise robot targeting method under portable x-ray fluoroscopy based on image servoing. The method is implemented for needle alignment in percutaneous procedures using the PAKY-RCM robot developed in our laboratory. Initial clinical tests apply to the access of the renal collecting system.

Robotic Kidney and Spine Percutaneous Procedures Using a New Laser-Based CT Registration Method

We present a simple method for robot registration in computer tomography imaging systems. Lhe method uses the laser markers readily available on any CL scanner and does not require imaging thus eliminating radiation exposure. Its accuracy is inherited from the laser positioning system. This approach does not require additional hardware, laser alignment being performed on the instrument used in the clinical application. Moreover, robotic guidance allows for radiological interventions to be performed on scanners without fluoro-CL capability. Unlike the manual approach, the method allows for performing oblique insertions, for which the skm entry point and the target are located indifferent slices.The implementation is realized using the latest version of the PAKY-RCM robot developed in our laboratory. This is an increased precision system based on our new Ball-Worm technology.The system was successfully used for five CL-guided biopsy and radio-frequency ablation procedures on the kidney and spine and a nephrostomy tube placement. Further investigation will explore its application to other organs and procedures.