Multi-Imager Compatible, MR Safe, Remote Center of Motion Needle-Guide Robot

Towards Design and Development of an MRI Conditional Robot to Enable Curvilinear Transperineal Prostate Biopsy

BACKGROUND

In-bore MRI prostate biopsy offers improved visualisation and detection of significant prostate cancer; however, it is not widely practiced in cancer diagnosis due to its associated costs.

METHODS

This work introduces the first prototype towards a 7-degrees-of-freedom (DOF) MRI-conditional piezoelectrically actuated robotic system for transperineal prostate biopsy. The robot enables needle insertions in the desired trajectories. Kinematic and static models of the active needle as well as automated control of the robot are presented.

RESULTS

It is shown that the controller can force the needle to realize the reference sine and triangular bending angles with an accuracy of 1.78 and 1.88°, respectively, in air. The trajectory tracking capability of the system in free space is shown with an RMS error of 0.86 mm and a standard deviation of 0.36 mm.

CONCLUSIONS

The robot's capability to steer the needle towards target inside a phantom and extract a sample was evaluated.

Design and Calibration of Dual Sensor: Towards Simultaneous Instrument Tracking and Deformable Shape Sensing in Computer-Integrated Surgery

We introduce a novel integration of vision sensors in the form of a dual sensor system. The dual sensor system combines three distinct units: an optical localizer and two RGB-D sensors. This system is uniquely capable of concurrently providing real-time 3D shape information for deformable objects and accurate pose tracking data for medical instruments. This capability positions the dual sensor with immense potential for application in image-guided surgical navigation, robotic systems, and robot-assisted automation for surgical procedures involving deformable target objects. This paper provides an overview of the design, fabrication and a one-time calibration methodology of the dual sensor. An experiment was performed to assess the calibration accuracy of the dual sensor. Experimental results indicated that the dual sensor system delivers a level of accuracy that renders it suitable for deployment within the envisioned scope of applications.Clinical relevance- The presented dual sensor provides real-time shape scanning of intra-operatively deforming objects and instrument tracking capabilities simultaneously, contributing to successful outcomes of diverse computer-integrated surgeries dealing with non-rigid surgical targets such as breast, face, and incised skin area.

Realization and Control of Robotic Injection Prototype With Instantaneous Remote Center of Motion Mechanism

OBJECTIVE

Although there have been studies conducted on the instantaneous remote center of motion (RCM) mechanism, the general closed-loop control method has not been studied. Thus, this article fills that gap and employs the advantages of this mechanism to develop a novel injection system.

METHODS

The injection prototype involves the instantaneous RCM mechanism, insertion unit and injection unit. The RCM system is investigated in the presence of time-varying axial stiffness of the screw drive and underactuated case. For safe interaction, compliance control is designed in the insertion system. The stability of all separate systems is investigated with the bounded parameter variation rate. The injection prototype and a robot end-effector were then combined to perform injection.

RESULTS

Our RCM prototype can achieve a large workspace, and its control effectiveness was verified by multiple frameworks and comparison with previous studies. Compliance-controlled insertion can achieve accurate depth regulation and zero-impedance control for manually operating the needle. With the help of three-dimensional reconstruction and hand/eye calibration, the manipulator can guide the injection prototype to a proper pose for injection of a face model.

CONCLUSION

The injection prototype was successfully designed. The effectiveness of the whole control system was verified by simulations and experiments. The particular robotic injection task can be performed by the prototype.

SIGNIFICANCE

This article provides alternative schemes for developing an instantaneous RCM system, screw drive-based surgical tool, and robotic insertion with small needles.

Interactive Multi-Stage Robotic Positioner for Intra-Operative MRI-Guided Stereotactic Neurosurgery

Magnetic resonance imaging (MRI) demonstrates clear advantages over other imaging modalities in neurosurgery with its ability to delineate critical neurovascular structures and cancerous tissue in high-resolution 3D anatomical roadmaps. However, its application has been limited to interventions performed based on static pre/post-operative imaging, where errors accrue from stereotactic frame setup, image registration, and brain shift. To leverage the powerful intra-operative functions of MRI, e.g., instrument tracking, monitoring of physiological changes and tissue temperature in MRI-guided bilateral stereotactic neurosurgery, a multi-stage robotic positioner is proposed. The system positions cannula/needle instruments using a lightweight (203 g) and compact (Ø97 × 81 mm) skull-mounted structure that fits within most standard imaging head coils. With optimized design in soft robotics, the system operates in two stages: i) manual coarse adjustment performed interactively by the surgeon (workspace of ±30°), ii) automatic fine adjustment with precise (<0.2° orientation error), responsive (1.4 Hz bandwidth), and high-resolution (0.058°) soft robotic positioning. Orientation locking provides sufficient transmission stiffness (4.07 N/mm) for instrument advancement. The system's clinical workflow and accuracy is validated with lab-based (<0.8 mm) and MRI-based testing on skull phantoms (<1.7 mm) and a cadaver subject (<2.2 mm). Custom-made wireless omni-directional tracking markers facilitated robot registration under MRI.

Measurement of Magnetically Induced Torque on Lightweight Medical Devices in the Magnetic Resonance Environment for ASTM F2213

OBJECTIVE

Use of medical devices in the magnetic resonance environment is regulated by standards that include the ASTM-F2213 magnetically induced torque. This standard prescribes five tests. However, none can be directly applied to measure very low torques of slender lightweight devices such as needles.

METHODS

We present a variant of an ASTM torsional spring method that makes a "spring" of 2 strings that suspend the needle by its ends. The magnetically induced torque on the needle causes it to rotate. The strings tilt and lift the needle. At equilibrium, the magnetically induced potential energy is balanced by the gravitational potential energy of the lift. Static equilibrium allows calculating the torque from the needle rotation angle, which is measured. Moreover, a maximum rotation angle corresponds to the maximum acceptable magnetically induced torque, under the most conservative ASTM acceptability criterion. A simple apparatus using the 2-string method is shown, it can be 3D printed, and the design files are shared.

RESULTS

The analytical methods were tested against a numeric dynamic model, showing perfect concordance. The method was then tested experimentally in 1.5T and 3T MRI with commercial biopsy needles. Numeric test errors were immeasurably small. Torques between 0.0001 Nm and 0.0018 Nm were measured in MRI with 7.7% maximum difference between tests. The cost to make the apparatus is 58USD and design files are shared.

CONCLUSION

The apparatus is simple and inexpensive and provides good accuracy as well.

SIGNIFICANCE

The 2-string method provides a solution to measure very low torques in the MRI.

MR-guided HDR prostate brachytherapy with teleoperated steerable needles

Conformity of tumour volumes and dose plans in prostate brachytherapy (BT) can be constrained by unwanted needle deflections, needle access restrictions and visualisation limitations. This work validates the feasibility of teleoperated robotic control of an active steerable needle using magnetic resonance (MR) for guidance. With this system, perturbations can be counteracted and critical structures can be circumvented to access currently inaccessible areas. The system comprises of (1) a novel steerable needle, (2) the minimally invasive robotics in an MR environment (MIRIAM) system, and (3) the daVinci Research Kit (dVRK). MR scans provide visual feedback to the operator controlling the dVRK. Needle steering is performed along curved trajectories to avoid the urethra towards targets (representing tumour tissue) in a prostate phantom with a targeting error of 1.2 ± 1.0 mm. This work shows the potential clinical applicability of active needle steering for prostate BT with a teleoperated robotic system in an MR environment.

Dimensional optimisation and an inverse kinematic solution method of a safety-enhanced remote centre of motion manipulator

BACKGROUND

With the expansion of minimally invasive surgery (MIS) applications in surgery, the remote centre of motion (RCM) manipulator requires a more flexible workspace to meet different operation requirements. Thus, the mechanical structure and motion control of the RCM manipulator play important roles.

METHODS

A multi-objective genetic algorithm was exploited to maximise the kinematic performance and obtain a compact structure of the RCM manipulator. An inverse kinematic solution method is proposed to meet task accuracy and kinematic singularity avoidance constraints for safety motion control.

RESULTS

Simulation results demonstrate that there are significant improvements in the reachable workspace inside the abdominal cavity, the flexibility of the workspace, kinematic performance, and compactness of the RCM manipulator. Experiments verify the feasibility of the prototype and the validity of the proposed inverse kinematic solution method.

CONCLUSIONS

This enhances the adaptability and safety of the RCM manipulator and provides potential prospects for MIS application.

Image-guided prostate biopsy robots: A review

At present, the incidence of prostate cancer (PCa) in men is increasing year by year. So, the early diagnosis of PCa is of great significance. Transrectal ultrasonography (TRUS)-guided biopsy is a common method for diagnosing PCa. The biopsy process is performed manually by urologists but the diagnostic rate is only 20%-30% and its reliability and accuracy can no longer meet clinical needs. The image-guided prostate biopsy robot has the advantages of a high degree of automation, does not rely on the skills and experience of operators, reduces the work intensity and operation time of urologists and so on. Capable of delivering biopsy needles to pre-defined biopsy locations with minimal needle placement errors, it makes up for the shortcomings of traditional free-hand biopsy and improves the reliability and accuracy of biopsy. The integration of medical imaging technology and the robotic system is an important means for accurate tumor location, biopsy puncture path planning and visualization. This paper mainly reviews image-guided prostate biopsy robots. According to the existing literature, guidance modalities are divided into magnetic resonance imaging (MRI), ultrasound (US) and fusion image. First, the robot structure research by different guided methods is the main line and the actuators and material research of these guided modalities is the auxiliary line to introduce and compare. Second, the robot image-guided localization technology is discussed. Finally, the image-guided prostate biopsy robot is summarized and suggestions for future development are provided.

Flexible Needle Bending Model for Spinal Injection Procedures

An in situ needle manipulation technique used by physicians when performing spinal injections is modeled to study its effect on needle shape and needle tip position. A mechanics-based model is proposed and solved using finite element method. A test setup is presented to mimic the needle manipulation motion. Tissue phantoms made from plastisol as well as porcine skeletal muscle samples are used to evaluate the model accuracy against medical images. The effect of different compression models as well as model parameters on model accuracy is studied, and the effect of needle-tissue interaction on the needle remote center of motion is examined. With the correct combination of compression model and model parameters, the model simulation is able to predict needle tip position within submillimeter accuracy.

Challenges regarding MR compatibility of an MRgFUS robotic system

Numerous challenges are faced when employing Magnetic Resonance guided Focused Ultrasound (MRgFUS) hardware in the Magnetic Resonance Imaging (MRI) setting. The current study aimed to provide insights on this topic through a series of experiments performed in the framework of evaluating the MRI compatibility of an MRgFUS robotic device. All experiments were performed in a 1.5 T MRI scanner. The main metric for MRI compatibility assessment was the signal to noise ratio (SNR). Measurements were carried out in a tissue mimicking phantom and freshly excised pork tissue under various activation states of the system. In the effort to minimize magnetic interference and image distortion, various set-up parameters were examined. Significant SNR degradation and image distortion occurred when the FUS transducer was activated mainly owing to FUS-induced target and coil vibrations and was getting worse as the output power was increased. Proper design and stable positioning of the imaged phantom play a critical role in reducing these vibrations. Moreover, isolation of the phantom from the imaging coil was proven essential for avoiding FUS-induced vibrations from being transferred to the coil during sonication and resulted in a more than 3-fold increase in SNR. The use of a multi-channel coil increased the SNR by up to 50 % compared to a single-channel coil. Placement of the electronics outside the coil detection area increased the SNR by about 65 %. A similar SNR improvement was observed when the encoders' counting pulses were deactivated. Overall, this study raises awareness about major challenges regarding operation of an MRgFUS system in the MRI environment and proposes simple measures that could mitigate the impact of noise sources so that the monitoring value of MR imaging in FUS applications is not compromised.

MRI Distortion Correction and Robot-to-MRI Scanner Registration for an MRI-Guided Robotic System

Magnetic resonance imaging (MRI) guided robotic procedures require safe robotic instrument navigation and precise target localization. This depends on reliable tracking of the instrument from MR images, which requires accurate registration of the robot to the scanner. A novel differential image based robot-to-MRI scanner registration approach is proposed that utilizes a set of active fiducial coils, where background subtraction method is employed for coil detection. In order to use the presented preoperative registration approach jointly with the real-time high speed MRI image acquisition and reconstruction methods in real-time interventional procedures, the effects of the geometric MRI distortion in robot to scanner registration is analyzed using a custom distortion mapping algorithm. The proposed approach is validated by a set of target coils placed within the workspace, employing multi-planar capabilities of the scanner. Registration and validation errors are respectively 2.05 mm and 2.63 mm after the distortion correction showing an improvement of respectively 1.08 mm and 0.14 mm compared to the results without distortion correction.

An integrated navigation system based on a dedicated breast support device for MRI-guided breast biopsy

PURPOSE

Breast cancer is currently the cancer type with the highest incidence in the world, and it is extremely harmful to women's health. MRI-guided breast biopsy is a common method in clinical examination of breast cancer. However, traditional breast biopsy is less accurate and takes a long time. In this study, an integrated navigation system (INS) based on a dedicated breast support device (DBSD) was proposed to assist doctors in biopsy.

METHODS

The grid-shaped DBSD can reduce the displacement and deformation of the breast during the biopsy operation and is convenient for puncture. The robot system based on the DBSD is designed to assist doctors in performing puncture action. The software system has functions such as registration, path planning, and real-time tracking of biopsy needles based on the DBSD, which can assist doctors in completing the entire biopsy procedure. A series of experiments are designed to verify the feasibility and accuracy of the system.

RESULTS

Experiments prove that the robot system has reasonable structure and meets the requirements of MR compatibility. The latency of the INS during intraoperative navigation is 0.30 ± 0.03 s. In the phantom puncture experiment, the puncture error under the navigation of the INS is 1.04 ± 0.15 mm.

CONCLUSION

The INS proposed in this paper can be applied to assist doctors in breast biopsy in MR environment, improve the accuracy of biopsy and shorten the time of biopsy. The experimental results show that the system is feasible and accurate.

A Dual-Armed Robotic Puncture System: Design, Implementation and Preliminary Tests

Traditional renal puncture surgery requires manual operation, which has a poor puncture effect, low surgical success rate, and high incidence of postoperative complications. Robot-assisted puncture surgery can effectively improve the accuracy of punctures, improve the success rate of surgery, and reduce the occurrence of postoperative complications. This paper provides a dual-armed robotic puncture scheme to assist surgeons. The system is divided into an ultrasound scanning arm and a puncture arm. Both robotic arms with a compliant positioning function and master–slave control function are designed, respectively, and the control system is achieved. The puncture arm’s position and posture are decoupled by the wrist RCM mechanism and the arm decoupling mechanism. According to the independent joint control principle, the compliant positioning function is realized based on the single-joint human–computer interactive admittance control. The simulation and tests verify its functions and performance. The differential motion incremental master–slave mapping strategy is used to realize the master–slave control function. The error feedback link is introduced to solve the cumulative error problem in the master–slave control. The dual-armed robotic puncture system prototype is established and animal tests verify the effectiveness.

A Brief Insight on Magnetic Resonance Conditional Neurosurgery Robots

The brain is a delicate organ in the human body that requires extreme care. Brain-related diseases are unavoidable. Perse, neurosurgery is a complicated procedure that demands high precision and accuracy. Developing a surgical robot is a complex task. To date, there are only a handful of neurosurgery robots in the market that distinctly undergo clinical procedures. These robots have exorbitant cost that hinders the utmost care progress in the area as they are unaffordable. This paper looked at the historical perspective and presented insight literature of the magnetic resonance conditional stereotactic neurosurgery robots that find their ways in clinics, abandoning research projects and promising research yet to undergo clinical use. In addition, the study also gives a thorough insight into the advantage of magnetic resonance imaging modalities and magnetic resonance conditional robots and the future challenges in automation use. Image compatibility test data and accuracy results are also examined because they guarantee that these systems work correctly in particular imaging settings. The primary differences between these systems include actuation and control technologies, construction materials, and the degree of freedom. Thus, one system has an advantage over the other.

Towards Safe In Situ Needle Manipulation for Robot Assisted Lumbar Injection in Interventional MRI

Lumbar injection is an image-guided procedure performed manually for diagnosis and treatment of lower back pain and leg pain. Previously, we have developed and verified an MR-Conditional robotic solution to assisting the needle insertion process. Drawing on our clinical experiences, a virtual remote center of motion (RCM) constraint is implemented to enable our robot to mimic a clinician's hand motion to adjust the needle tip position in situ. Force and image data are collected to study the needle behavior in gel phantoms during this motion, and a mechanics-based needle-tissue interaction model is proposed and evaluated to further examine the underlying physics. This work extends the commonly-adopted notion of an RCM for flexible needles, and introduces new motion parameters to describe the needle behavior. The model parameters can be tuned to match the experimental result to sub-millimeter accuracy, and this proposed needle manipulation method presents a safer alternative to laterally translating the needle during in situ needle adjustments.

Multi-Bevel Needle Design Enabling Accurate Insertion in Biopsy for Cancer Diagnosis

OBJECTIVE

To obtain definitive cancer diagnosis for suspicious lesions, accurate needle deployment and adequate tissue sampling in needle biopsy are essential. However, the single-bevel needles in current biopsy devices often induce deflection during insertion, potentially causing lesion missampling/undersampling and cancer misdiagnosis. This study aims to reveal the biopsy needle design criteria enabling both low deflection and adequate tissue sampling.

METHODS

A novel model capable of predicting needle deflection and tissue deformation was first established to understand needle-tissue interaction with different needle tip geometries. Experiments of needle deflection and ex-vivo tissue biopsy were conducted for model validation.

RESULTS

The developed model showed a reasonably good prediction on the correlation of needle tip type vs. the resultant needle deflection and tissue sampling length. A new multi-bevel needle with the tissue separation point below the needle groove face has demonstrated to be an effective design with an 87% reduction in deflection magnitude and equivalently long tissue sampling length compared to the current single-bevel needle.

CONCLUSION

This study has revealed two critical design criteria for biopsy needles: 1) multiple bevel faces at the needle tip can generate forces to balance bending moments during insertion to enable a low needle deflection and 2) the tissue separation point should be below the needle groove face to ensure long tissue sampling length.

SIGNIFICANCE

The developed methodologies and findings in this study serve as proof-of-concept and can be utilized to investigate various biopsy procedures to improve cancer diagnostic accuracy as well as other procedures requiring accurate needle insertion.

Workflow-Based Design and Evaluation of a Device for CBCT-Guided Biopsy

Biopsies for personalized cancer care can be performed with cone beam computed tomography (CBCT) guidance, but manual needle manipulation remains an issue due to X-ray exposure to physicians. Modern CBCT scanners integrate today real-time imaging and software assistance for needle planning. In this paper, these available features are exploited to design a novel device offering an intermediate level of assistance between simple passive mechanical devices of limited efficiency, and advanced robotic devices requiring adapted procedure workflows. Our resulting system is built to limit its impact on the current manual practice. It is patient-mounted and provides remote control of needle orientation and insertion. A multilayer phantom is specifically developed to reproduce interactions between the needle and soft abdominal tissues. It is used to experimentally evaluate the device added value by comparing assisted versus manual needle insertions. The device is shown to help reducing X-ray exposure by a factor 4, without impacting the accuracy obtained manually.

EXPERIMENTAL STUDY OF DOUBLE CABLE-CONDUIT DRIVING DEVICE FOR MRI COMPATIBLE BIOPSY ROBOTS

Magnetic resonance imaging (MRI) is better than other imaging equipment in detecting tumors, and navigation for robotic breast intervention biopsy. However, material requirements for robots driving devices are demanding incredibly because of the environment. Given this problem, a novel double cable-conduit driving method is put forward in this paper, which can be used in MRI for breast intervention robots. Besides, lebus grooves are adopted to the driving wheels, which enable the system to realize remote-range and large-scale driving on the premise that the precision can be further enhanced. The driving characteristic of the novel cable-conduit is established. Moreover, the cable-conduit experimental data proves the results of theoretical deduction. Finally, the cable-conduit driving device is compensated, the average errors in the [Formula: see text], [Formula: see text], and [Formula: see text] directions of the needle tip entering the tissue are less than 2[Formula: see text]mm. The consequence verifies that it can meet the requirements for breast biopsy robot application under MR environment.

Ultrasound-guided needle insertion robotic system for percutaneous puncture

PURPOSE

Ultrasound (US)-guided percutaneous puncture technology can realize real-time, minimally invasive interventional therapy without radiation. The location accuracy of the puncture needle directly determines the precision and safety of the operation. It is a challenge for novices and young surgeons to perform a free-hand puncture guided by the ultrasound images to achieve the desired accuracy. This work aims to develop a robotic system to assist surgeons to perform percutaneous punctures with high precision.

METHODS

An US-guided puncture robot was designed to allow the mounting and control of the needle to achieve localization and insertion. The US probe fitted within the puncture robot was held by a passive arm. Moreover, the puncture robot was calibrated with a novel calibration method to achieve coordinate transformation between the robot and the US image. The system allowed the operators to plan the puncture target and puncture path on US images, and the robot performed needle insertion automatically. Five groups of puncture experiments were performed to verify the validity and accuracy of the proposed robotic system.

RESULTS

Assisted by the robotic system, the positioning and orientation accuracies of the needle insertion were 0.9 ± 0.29 mm and 0.76 ± 0.34°, respectively. These are improved compared with the results obtained with the free-hand puncture (1.82 ± 0.51 mm and 2.79 ± 1.32°, respectively). Moreover, the proposed robotic system can reduce the operation time and number of needle insertions (14.28 ± 3.21 s and one needle insertion, respectively), compared with the free-hand puncture (25.14 ± 6.09 s and 1.96 ± 0.68 needle insertions, respectively).

CONCLUSION

A robotic system for percutaneous puncture guided by US images was developed and demonstrated. The experimental results indicate that the proposed system is accurate and feasible. It can assist novices and young surgeons to perform the puncture operation with increased accuracy.

MR-Conditional Actuations: A Review

Magnetic resonance imaging (MRI) is one of the most prevailing technologies to enable noninvasive and radiation-free soft tissue imaging. Operating a robotic device under MRI guidance is an active research area that has the potential to provide efficient and precise surgical therapies. MR-conditional actuators that can safely drive these robotic devices without causing safety hazards or adversely affecting the image quality are crucial for the development of MR-guided robotic devices. This paper aims to summarize recent advances in actuation methods for MR-guided robots and each MR-conditional actuator was reviewed based on its working principles, construction materials, the noteworthy features, and corresponding robotic application systems, if any. Primary characteristics, such as torque, force, accuracy, and signal-to-noise ratio (SNR) variation due to the variance of the actuator, are also covered. This paper concludes with a perspective on the current development and future of MR-conditional actuators.

Design and control of a bionic needle puncture robot

BACKGROUND

The application of minimally invasive interventional breast surgery is becoming more and more widespread. The accurate puncture of breast cancer needs to solve the problems of tissue deformation and target displacement.

METHODS

In this study, we analysed the process of leech blood absorption and developed a robotic needle insertion method based on bionic technology to improve the accuracy of breast cancer diagnosis and treatment. Among them, the design purpose of the sucker manipulator is to adjust and fix the breast tissue. We use uncalibrated visual servo to control soft tissue deformation.

RESULTS

We compare the puncture effect of bionic needle puncture robot and common needle puncture on breast prosthesis and in vitro tissue. Experimental data shows that, compared with ordinary needle insertion, the robotic needle insertion method based on bionic technology greatly reduces the targeting error.

CONCLUSIONS

This method is expected to provide a safe and effective alternative to traditional puncture for breast cancer diagnosis and treatment.

Differential Image Based Robot to MRI Scanner Registration with Active Fiducial Markers for an MRI-Guided Robotic Catheter System

In magnetic resonance imaging (MRI) guided robotic catheter ablation procedures, reliable tracking of the catheter within the MRI scanner is needed to safely navigate the catheter. This requires accurate registration of the catheter to the scanner. This paper presents a differential, multi-slice image-based registration approach utilizing active fiducial coils. The proposed method would be used to preoperatively register the MRI image space with the physical catheter space. In the proposed scheme, the registration is performed with the help of a registration frame, which has a set of embedded electromagnetic coils designed to actively create MRI image artifacts. These coils are detected in the MRI scanner's coordinate system by background subtraction. The detected coil locations in each slice are weighted by the artifact size and then registered to known ground truth coil locations in the catheter's coordinate system via least-squares fitting. The proposed approach is validated by using a set of target coils placed withing the workspace, employing multi-planar capabilities of the MRI scanner. The average registration and validation errors are respectively computed as 1.97 mm and 2.49 mm. The multi-slice approach is also compared to the single-slice method and shown to improve registration and validation by respectively 0.45 mm and 0.66 mm.

Demonstration and Experimental Validation of Plastic-Encased Resonant Ultrasonic Piezoelectric Actuator for Magnetic Resonance Imaging-Guided Surgical Robots

Intra-operative medical imaging based on magnetic resonance imaging (MRI) coupled with robotic manipulation of surgical instruments enables precise feedback-driven procedures. Electrically powered nonferromagnetic motors based on piezoelectric elements have shown to be well suited for MRI robots. However, even avoiding ferrous materials, the high metal content on commercially available motors still cause distortions to the magnetic fields. We construct semicustom piezoelectric actuators wherein the quantity of conductive material is minimized and demonstrate that the distortion issues can be partly addressed through substituting several of these components for plastic equivalents, while maintaining motor functionality. Distortion was measured by assessing the root-mean-squared (RMS) change in position of 49 centroid points in a 12.5 mm square grid of a gelatin-filled phantom. The metal motor caused a distortion of up to 4.91 mm versus 0.55 mm for the plastic motor. An additional signal-to-noise-ratio (SNR) drop between motor off and motor spinning of approximately 20% was not statistically different for metal versus plastic (p = 0.36).

Needle deflection and tissue sampling length in needle biopsy

This study investigates the effect of needle tip geometry on the needle deflection and tissue sampling length in biopsy. Advances in medical imaging have allowed the identification of suspicious cancerous lesions which then require needle biopsy for tissue sampling and subsequent confirmatory pathological analysis. Precise needle insertion and adequate tissue sampling are essential for accurate cancer diagnosis and individualized treatment decisions. However, the single-bevel needles in current hand-held biopsy devices often deflect significantly during needle insertion, causing variance in the targeted and actual locations of the sampled tissue. This variance can lead to inaccurate sampling and false-negative results. There is also a limited understanding of factors affecting the tissue sampling length which is a critical component of accurate cancer diagnosis. This study compares the needle deflection and tissue sampling length between the existing single-bevel and exploratory multi-bevel needle tip geometries. A coupled Eulerian-Lagrangian finite element analysis was applied to understand the needle-tissue interaction during needle insertion. The needle deflection and tissue sampling length were experimentally studied using tissue-mimicking phantoms and ex-vivo tissue, respectively. This study reveals that the tissue separation location at the needle tip affects both needle deflection and tissue sampling length. By varying the tissue separation location and creating a multi-bevel needle tip geometry, the bending moments induced by the insertion forces can be altered to reduce the needle deflection. However, the tissue separation location also affects the tissue contact inside the needle groove, potentially reducing the tissue sampling length. A multi-bevel needle tip geometry with the tissue separation point below the needle groove face may reduce the needle deflection while maintaining a long tissue sampling length. Results from this study can guide needle tip design to enable the precise needle deployment and adequate tissue sampling for the needle biopsy procedures.

Magnetic resonance and ultrasound image-guided navigation system using a needle manipulator

PURPOSE

Image guidance is crucial for percutaneous tumor ablations, enabling accurate needle-like applicator placement into target tumors while avoiding tissues that are sensitive to injury and/or correcting needle deflection. Although ultrasound (US) is widely used for image guidance, magnetic resonance (MR) is preferable due to its superior soft tissue contrast. The objective of this study was to develop and evaluate an MR and US multi-modal image-guided navigation system with a needle manipulator to enable US-guided applicator placement during MR imaging (MRI)-guided percutaneous tumor ablation.

METHODS

The MRI-compatible needle manipulator with US probe was installed adjacent to a 3 Tesla MRI scanner patient table. Coordinate systems for the MR image, patient table, manipulator, and US probe were all registered using an optical tracking sensor. The patient was initially scanned in the MRI scanner bore for planning and then moved outside the bore for treatment. Needle insertion was guided by real-time US imaging fused with the reformatted static MR image to enhance soft tissue contrast. Feasibility, targeting accuracy, and MR compatibility of the system were evaluated using a bovine liver and agar phantoms.

RESULTS

Targeting error for 50 needle insertions was 1.6 ± 0.6 mm (mean ± standard deviation). The experiment confirmed that fused MR and US images provided real-time needle localization against static MR images with soft tissue contrast.

CONCLUSIONS

The proposed MR and US multi-modal image-guided navigation system using a needle manipulator enabled accurate needle insertion by taking advantage of static MR and real-time US images simultaneously. Real-time visualization helped determine needle depth, tissue monitoring surrounding the needle path, target organ shifts, and needle deviation from the path.

Design and implementation of a new cable-driven robot for MRI-guided breast biopsy

BACKGROUND

Breast cancer is one of the most common cancer diagnosed among US women. Early and accurate diagnosis using breast biopsy techniques is essential in detecting cancer.

METHODS

In this paper, we present a new cable-driven robot for MRI-guided breast biopsy. A compact three degree-of-freedom (DOF) semi-automated robot driven by ultrasonic motors is designed with non-magnetic materials. Next, a novel insertion trajectory planning algorithm based on the breast holder that we created is proposed and designed, which can help radiologists locate the lesion and calculate the insertion trajectory. To improve the accuracy of insertion, kinematic analysis and accuracy compensation methods are introduced.

RESULTS

An experimental study based on image recognition and positioning is performed to validate the performance of the new robot. The results show that the mean position accuracy is 0.7 ± 0.04 mm.

CONCLUSIONS

Application of the new robot can improve breast biopsy accuracy and reduce surgery time.

Pressure Observer Based Adaptive Dynamic Surface Control of Pneumatic Actuator with Long Transmission Lines

In this paper, the needle insertion motion control of a magnetic resonance imaging (MRI) compatible robot, which is actuated by a pneumatic cylinder with long transmission lines, is considered and a pressure observer based adaptive dynamic surface controller is proposed. The long transmission line is assumed to be an intermediate chamber connected between the control valve and the actuator in series, and a nonlinear first order system model is constructed to characterize the pressure losses and time delay brought by it. Due to the fact that MRI-compatible pressure sensors are not commercially available, a globally stable pressure observer is employed to estimate the chamber pressure. Based on the model of the long transmission line and the pressure observer, an adaptive dynamic surface controller is further designed by using the dynamic surface control technique. Compared to the traditional backstepping design method, the proposed controller can avoid the problem of “explosion of complexity” since the repeated differentiation of virtual controls is no longer required. The stability of the closed-loop system is analytically proven by employing the Lyapunov theory. Extensive experimental results are presented to demonstrate the effectiveness and the performance robustness of the proposed controller.

Robotic Transrectal Ultrasound Guided Prostate Biopsy

We present a robot-assisted approach for transrectal ultrasound (TRUS) guided prostate biopsy. The robot is a hands-free probe manipulator that moves the probe with the same 4 DoF that are used manually. Software was developed for three-dimensional (3-D) imaging, biopsy planning, robot control, and navigation. Methods to minimize the deformation of the prostate caused by the probe at 3-D imaging and needle targeting were developed to reduce biopsy targeting errors. We also present a prostate coordinate system (PCS). The PCS helps defining a systematic biopsy plan without the need for prostate segmentation. Comprehensive tests were performed, including two bench tests, one imaging test, two in vitro targeting tests, and an IRB-approved clinical trial on five patients. Preclinical tests showed that image-based needle targeting can be accomplished with accuracy on the order of 1 mm. Prostate biopsy can be accomplished with minimal TRUS pressure on the gland and submillimetric prostate deformations. All five clinical cases were successful with an average procedure time of 13 min and millimeter targeting accuracy. Hands-free TRUS operation, transrectal TRUS guided prostate biopsy with minimal prostate deformations, and the PCS-based biopsy plan are novel methods. Robot-assisted prostate biopsy is safe and feasible. Accurate needle targeting has the potential to increase the detection of clinically significant prostate cancer.

Review of Robotic Needle Guide Systems for Percutaneous Intervention

Numerous research groups in the past have designed and developed robotic needle guide systems that improve the targeting accuracy and precision by either providing a physical guidance for manual insertion or enabling a complete automated intervention. Here we review systems that have been reported in the last 11 years and limited to straight line needle interventions. Most systems fall under the category of image guided systems as they either use magnetic resonance image, computed tomography, ultrasound or a combination of these modalities for real time image feedback of the intervention path being followed. Actuation and control technology along with materials used for construction are the main aspects that differentiate these systems from each other and have been reviewed here. Image compatibility test details and results are also reviewed as they are used to ensure proper functioning of these systems under the respective imaging environments. We have also reviewed needle guide systems which either don't use any image feedback or have not reported any but provide physical guidance. Throughout this paper, we provide a comprehensive review of the technological aspects and trends in the field of robotic, straight line, needle guide intervention systems.

DEMONSTRATION AND EXPERIMENTAL VALIDATION OF PLASTIC-ENCASED RESONANT ULTRASONIC PIEZOELECTRIC ACTUATOR FOR MRI-GUIDED SURGICAL ROBOTS

Intra-operative medical imaging based on magnetic resonance imaging (MRI) coupled with robotic manipulation of surgical instruments enables precise feedback-driven procedures. Electrically powered non-ferromagnetic motors based on piezoelectric elements have shown to be well suited for MRI robots. However, even avoiding ferrous materials, the high metal content on commercially available motors still cause distortions to the magnetic fields. We construct semi-custom piezoelectric actuators wherein the quantity of conductive material is minimized and demonstrate that the distortion issues can be partly addressed through substituting several of these components for plastic equivalents, while maintaining motor functionality. Distortion was measured by assessing the RMS change in position of 49 centroid points in a 12.5mm square grid of a gelatin-filled phantom. The metal motor caused a distortion of up to 4.91mm versus 0.55mm for the plastic motor. An additional SNR drop between motor off and motor spinning of approximately 20% was not statistically different for metal versus plastic (p=0.36).

MRI-guided robotic arm drives optogenetic fMRI with concurrent Ca2+ recording

Optical fiber-mediated optogenetic activation and neuronal Ca2+ recording in combination with fMRI provide a multi-modal fMRI platform. Here, we developed an MRI-guided robotic arm (MgRA) as a flexible positioning system with high precision to real-time assist optical fiber brain intervention for multi-modal animal fMRI. Besides the ex vivo precision evaluation, we present the highly reliable brain activity patterns in the projected basal forebrain regions upon MgRA-driven optogenetic stimulation in the lateral hypothalamus. Also, we show the step-wise optical fiber targeting thalamic nuclei and map the region-specific functional connectivity with whole-brain fMRI accompanied by simultaneous calcium recordings to specify its circuit-specificity. The MgRA also guides the real-time microinjection to specific deep brain nuclei, which is demonstrated by an Mn-enhanced MRI method. The MgRA represents a clear advantage over the standard stereotaxic-based fiber implantation and opens a broad avenue to investigate the circuit-specific functional brain mapping with the multi-modal fMRI platform.

Using Brain Activation to Evaluate Arrangements Aiding Hand-Eye Coordination in Surgical Robot Systems

GOAL

To realize intuitive, minimally invasive surgery, surgical robots are often controlled using master-slave systems. However, the surgical robot's structure often differs from that of the human body, so the arrangement between the monitor and master must reflect this physical difference. In this study, we validate the feasibility of an embodiment evaluation method that determines the arrangement between the monitor and master. In our constructed cognitive model, the brain's intraparietal sulcus activates significantly when somatic and visual feedback match. Using this model, we validate a cognitively appropriate arrangement between the monitor and master.

METHODS

In experiments, we measure participants' brain activation using an imaging device as they control the virtual surgical simulator. Two experiments are carried out that vary the monitor and hand positions.

CONCLUSION

There are two common arrangements of the monitor and master at the brain activation's peak: One is placing the monitor behind the master, so the user feels that the system is an extension of his arms into the monitor; the other arranges the monitor in front of the master, so the user feels the correspondence between his own arm and the virtual arm in the monitor.

SIGNIFICANCE

From these results, we conclude that the arrangement between the monitor and master impacts embodiment, enabling the participant to feel apparent posture matches in master-slave surgical robot systems.

Robotically assisted long bone biopsy under MRI: cadaver study results

RATIONALE AND OBJECTIVES

We have designed and constructed an MR-safe robot made entirely of nonmetallic components with pneumatic actuators and optical encoders. The robot was developed to enable bone biopsies to be performed under magnetic resonance imaging (MRI) guidance in pediatric patients. The purpose of this study was to show the feasibility of using the robot for biopsy of the femur and tibia in a cadaver leg. Our long-term goal is to eliminate radiation exposure during bone biopsy procedures and provide more timely and accurate diagnosis for children with bone cancers and bone infections.

METHODS

The MR-safe robot was mounted on the MRI table. A cadaver leg was procured from an anatomy supply house and placed on the MRI table. All required hospital precautions for infection control were taken. A total of 10 biopsy targets were sampled using MRI guidance: five from the femur and five from the tibia. A handheld, commercially available battery-powered bone drill was used to facilitate drilling through the cortex. After the study, the leg was scanned with CT to better visualize and document the bone biopsy sites. Both the MRI and CT images were used to analyze the results.

RESULTS

All of the targets were successfully reached with an average targeting accuracy of 1.43 mm. A workflow analysis showed the average time for the first biopsy was 41 min including robot setup time and 22 min for each additional biopsy including the time for the repeat MRI scan used to confirm accurate targeting. The robot was shown to be MRI transparent, as no image quality degradation due to the use of the robot was detected.

CONCLUSION

The results showed the feasibility of using an MR-safe robotic system to assist the interventional radiologist in performing precision bone biopsy under MRI guidance. Future work will include developing an MR-safe drill, improving the mounting of the robot and fixation of the leg, and moving toward first in child clinical trials.

New remote centre of motion mechanism for robot-assisted minimally invasive surgery

BACKGROUND

Robot-assisted minimally invasive surgery (RMIS) is promising for improving surgical accuracy and dexterity. As the end effector of the robotic arm, the remote centre of motion mechanism is one of the requisite terms for guaranteeing patient safety. The existing remote centre of motion mechanisms are complex and large in volume, as well as high assembly requirement and unsatisfactory precise. This paper aimed to present a new remote centre of motion mechanism for solving these problems.

METHODS

A new mechanism based on the RMIS requirements is proposed for holding the laparoscope and generating a remote centre of motion for the laparoscope. The mechanism kinematics is then analysed from the perspective of the structural function, and its inverse kinematics is determined with a small number of calculations. Finally, the position deviation of the laparoscope rotational point is chosen as the index to evaluate the mechanism performance. The experiments are performed to test the deviation.

RESULTS

The position deviations of the laparoscope rotational point do not exceed 2 mm, which is lower than that of the existing remote centre of motion mechanism. The 2 mm positioning error of the laparoscope won't affect surgeon observation of the surgical field, and the pressure caused by the positioning error was acceptable for the skin elasticity. The proposed mechanism meets the RMIS requirement.

CONCLUSIONS

The proposed mechanism can achieve the remote centre of motion for the laparoscope. Its simple and compact structure is beneficial to avoid the collision of robotic arms, and it can be applied on other robots for providing the instrument necessary motion in minimally invasive surgery.

Observations And Experiments For The Definition Of A New Robotic Device Dedicated To CT, CBCT And MRI-Guided Percutaneous Procedures

In this paper, we present the work achieved to define the robotic functionalities of interest for percutaneous procedures as performed in interventional radiology. Our contributions are twofold. First, a detailed task analysis is performed with workflow analysis of biopsies, one of the most frequent tasks, under three imaging modalities, namely CT, CBCT and MRI. Second, the functionalities of a robotic assistant are identified, and we analyze whether a single device can bring an added value during procedures in the three modalities while keeping the robotized workflow close to manual tasks, to minimize learning time and difficulty of use. Experimental analysis on CBCT is notably used to confirm the interest of the determined robotic functionalities.

Stereotactic Systems for MRI-Guided Neurosurgeries: A State-of-the-Art Review

Recent technological developments in magnetic resonance imaging (MRI) and stereotactic techniques have significantly improved surgical outcomes. Despite the advantages offered by the conventional MRI-guided stereotactic neurosurgery, the robotic-assisted stereotactic approach has potential to further improve the safety and accuracy of neurosurgeries. This review aims to provide an update on the potential and continued growth of the MRI-guided stereotactic neurosurgical techniques by describing the state of the art in MR conditional stereotactic devices including manual and robotic-assisted. The paper also presents a detailed overview of MRI-guided stereotactic devices, MR conditional actuators and encoders used in MR conditional robotic-assisted stereotactic devices. The review concludes with several research challenges and future perspectives, including actuator and sensor technique, MR image guidance, and robot design issues.

MRI Robots for Needle-Based Interventions: Systems and Technology

Magnetic resonance imaging (MRI) provides high-quality soft-tissue images of anatomical structures and radiation free imaging. The research community has focused on establishing new workflows, developing new technology, and creating robotic devices to change an MRI room from a solely diagnostic room to an interventional suite, where diagnosis and intervention can both be done in the same room. Closed bore MRI scanners provide limited access for interventional procedures using intraoperative imaging. MRI robots could improve access and procedure accuracy. Different research groups have focused on different technology aspects and anatomical structures. This paper presents the results of a systematic search of MRI robots for needle-based interventions. We report the most recent advances in the field, present relevant technologies, and discuss possible future advances. This survey shows that robotic-assisted MRI-guided prostate biopsy has received the most interest from the research community to date. Multiple successful clinical experiments have been reported in recent years that show great promise. However, in general the field of MRI robotic systems is still in the early stage. The continued development of these systems, along with partnerships with commercial vendors to bring this technology to market, is encouraged to create new and improved treatment opportunities for future patients.

Robotically Assisted Long Bone Biopsy Under MRI Imaging: Workflow and Preclinical Study

RATIONALE AND OBJECTIVES

Our research team has developed a magnetic resonance imaging (MRI)-compatible robot for long bone biopsy. The robot is intended to enable a new workflow for bone biopsy in pediatrics under MRI imaging. Our long-term objectives are to minimize trauma and eliminate radiation exposure when diagnosing children with bone cancers and bone infections. This article presents our robotic systems, phantom accuracy studies, and workflow analysis.

MATERIALS AND METHODS

This section describes several aspects of our work including the envisioned clinical workflow, the MRI-compatible robot, and the experimental setup. The workflow consists of five steps and is intended to enable the entire procedure to be completed in the MRI suite. The MRI-compatible robot is MR Safe, has 3 degrees of freedom, and a remote center of motion mechanism for orienting a needle guide. The accuracy study was done in a Siemens Aera 1.5T scanner with a long bone phantom. Four targeting holes were drilled in the phantom.

RESULTS

Each target was approached twice at slightly oblique angles using the robot needle guide for a total of eight attempts. A workflow analysis showed the average time for each targeting attempt was 32 minutes, including robot setup time. The average 3D targeting error was 1.39 mm with a standard deviation of 0.40 mm. All of the targets were successfully reached.

CONCLUSION

The results showed the ability of the robotic system in assisting the radiologist to precisely target a bone phantom in the MRI environment. The robot system has several potential advantages for clinical application, including the ability to work at the MRI isocenter and serve as a steady and precise guide.

Mechanical Validation of an MRI Compatible Stereotactic Neurosurgery Robot in Preparation for Pre-Clinical Trials

The use of magnetic resonance imaging (MRI) for guiding robotic surgical devices has shown great potential for performing precisely targeted and controlled interventions. To fully realize these benefits, devices must work safely within the tight confines of the MRI bore without negatively impacting image quality. Here we expand on previous work exploring MRI guided robots for neural interventions by presenting the mechanical design and assessment of a device for positioning, orienting, and inserting an interstitial ultrasound-based ablation probe. From our previous work we have added a 2 degree of freedom (DOF) needle driver for use with the aforementioned probe, revised the mechanical design to improve strength and function, and performed an evaluation of the mechanism's accuracy and effect on MR image quality. The result of this work is a 7-DOF MRI robot capable of positioning a needle tip and orienting it's axis with accuracy of 1.37 ± 0.06mm and 0.79° ± 0.41°, inserting it along it's axis with an accuracy of 0.06 ± 0.07mm, and rotating it about it's axis to an accuracy of 0.77° ± 1.31°. This was accomplished with no significant reduction in SNR caused by the robot's presence in the MRI bore, ≤ 10.3% reduction in SNR from running the robot's motors during a scan, and no visible paramagnetic artifacts.