A robotic needle-positioning and guidance system for CT-guided puncture: Ex vivo results

Innovations in Image-Guided Procedures: Unraveling Robot-Assisted Non-Hepatic Percutaneous Ablation

Interventional oncology is routinely tasked with the feat of tumor characterization or destruction, via image-guided biopsy and tumor ablation, which may pose difficulties due to challenging-to-reach structures, target complexity, and proximity to critical structures. Such procedures carry a risk-to-benefit ratio along with measurable radiation exposure. To streamline the complexity and inherent variability of these interventions, various systems, including table-, floor-, gantry-, and patient-mounted (semi-) automatic robotic aiming devices, have been developed to decrease human error and interoperator and intraoperator outcome variability. Their implementation in clinical practice holds promise for enhancing lesion targeting, increasing accuracy and technical success rates, reducing procedure duration and radiation exposure, enhancing standardization of the field, and ultimately improving patient outcomes. This narrative review collates evidence regarding robotic tools and their implementation in interventional oncology, focusing on clinical efficacy and safety for nonhepatic malignancies.

Robotic systems in interventional oncology: a narrative review of the current status

Interventional oncology offers minimally invasive treatments for malignant tumors for curative and palliative purposes based on the percutaneous insertion of needles or catheters into the target location under image guidance. Robotic systems have been gaining increasing attention as tools that provide potential advantages for image-guided interventions. Among the robotic systems developed for intervention, those relevant to the oncology field are mainly those for guiding or driving the needles in non-vascular interventional procedures such as biopsy and tumor ablation. Needle-guiding robots support planning the needle path and align the needle robotically according to the planned trajectory, which is combined with subsequent manual needle insertion by the physician through the needle guide. Needle-driving robots can advance the needle robotically after determining its orientation. Although a wide variety of robotic systems have been developed, only a limited number of these systems have reached the clinical phase or commercialization thus far. The results of previous studies suggest that such interventional robots have the potential to increase the accuracy of needle placement, facilitate out-of-plane needle insertion, decrease the learning curve, and reduce radiation exposure. On the other hand, increased complexity and costs may be a concern when using robotic systems compared with conventional manual procedures. Further data should be collected to comprehensively assess the value of robotic systems in interventional oncology.

Stereotactic ablation: A game changer?

For both primary and metastatic liver cancer, thermal ablation represents an interesting alternative to surgery. However, except for a small fraction of patients, conventional ultrasound- and CT-guided single-probe approaches have not achieved oncologic outcomes comparable with surgery. In this overview, we describe our stereotactic ablation workflow and discuss the short- and long-term results of stereotactic radiofrequency ablation (SRFA) and stereotactic microwave ablation (SMWA) for the treatment of primary and secondary liver tumours. The advantages of this method are discussed together with a summary of the existing stereotactic techniques for thermal ablation and the clinical data that support them. Stereotactic ablation is based on an optical navigation system and a specialized aiming tool. The workflow includes advanced three-dimensional planning, precise needle/probe placements according to the plan and intraoperative image fusion to check the needle positions and the ablation margins. Stereotactic ablation offers all the advantages of a minimally invasive procedure while producing oncological results comparable with surgery. The number of locally treatable liver cancers may be significantly expanded with these cutting-edge instruments and methods. We firmly believe that it can become a cornerstone in the treatment of liver cancers.

Preliminary evaluation for ultrasound-guided targeted prostate biopsy using a portable surgical robot: Ex vivo results

BACKGROUND

Robotic systems are increasingly used to enhance clinical outcomes in prostate intervention. To evaluate the clinical value of the proposed portable robot, the robot-assisted and robot-targeted punctures were validated experimentally.

METHOD

The robot registration utilising the electromagnetic tracker achieves coordinate transformation from the ultrasound (US) image to the robot. Subsequently, Transrectal ultrasound (TRUS)-guided phantom trials were conducted for robot-assisted, free-hand, and robot-targeted punctures.

RESULTS

The accuracy of robot registration was 0.95 mm, and the accuracy of robot-assisted, free-hand, and robot-targeted punctures was 2.38 ± 0.64 mm, 3.11 ± 0.72 mm, and 3.29 ± 0.83 mm sequentially.

CONCLUSION

The registration method has been successfully applied to robot-targeted puncture. Current results indicate that the accuracy of robot-targeted puncture is slightly inferior to that of manual operations. Moreover, in manual operation, robot-assisted puncture improves the accuracy of free-hand puncture. Accuracy superior to 3.5 mm demonstrates the clinical applicability of both robot-assisted and robot-targeted punctures.

Current State of Robotics in Interventional Radiology

As a relatively new specialty with a minimally invasive nature, the field of interventional radiology is rapidly growing. Although the application of robotic systems in this field shows great promise, such as with increased precision, accuracy, and safety, as well as reduced radiation dose and potential for teleoperated procedures, the progression of these technologies has been slow. This is partly due to the complex equipment with complicated setup procedures, the disruption to theatre flow, the high costs, as well as some device limitations, such as lack of haptic feedback. To further assess these robotic technologies, more evidence of their performance and cost-effectiveness is needed before their widespread adoption within the field. In this review, we summarise the current progress of robotic systems that have been investigated for use in vascular and non-vascular interventions.

Evaluation of the performance of robot assisted CT-guided percutaneous needle insertion: Comparison with freehand insertion in a phantom

PURPOSE

To evaluate the performance of a novel robot for CT-guided needle positioning procedures and compare it to the freehand technique in an abdominal phantom.

METHODS

One interventional radiology fellow and one experienced interventional radiologist (IR) performed twelve robot-assisted and twelve freehand needle positionings in a phantom over predetermined trajectories. The robot automatically aimed a needle-guide according to the planned trajectories, after which the clinician manually inserted the needle. Using repeated CT scans, the needle position was assessed and adjusted if the clinician deemed it necessary. Technical success, accuracy, number of position adjustments, and procedure time were measured. All outcomes were analyzed using descriptive statistics and were compared between the robot-assisted and freehand procedures using the paired t-test and Wilcoxon signed rank test.

RESULTS

Compared with the freehand technique, the robot system improved the number of technically successfully needle targeting (20/24 vs 14/24), with higher accuracy (mean Euclidean deviation from target center: 3.5 ± 1.8 mm vs 4.6 ± 2.1 mm, p = 0.02) and required fewer needle position adjustments (0.0 ± 0.2 steps vs 1.7 ± 0.9 steps, p < 0.001), respectively. The robot improved the needle positioning for both, the fellow and the expert IR, compared to their freehand performances, with more improvement for the fellow than for the expert IR. The procedure time was similar for the robot-assisted and freehand procedures (19.5 ± 9.2 min. vs 21.0 ± 6.9 min., p = 0.777).

CONCLUSIONS

CT-guided needle positioning with the robot was more successful and accurate than freehand needle positioning and required fewer needle position adjustments without prolonging the procedure.

Phantom and Animal Study of a Robot-Assisted, CT-Guided Targeting System using Image-Only Navigation for Stereotactic Needle Insertion without Positional Sensors

PURPOSE

To evaluate the feasibility and accuracy of a robotic system to integrate and map computed tomography (CT) and robotic coordinates, followed by automatic trajectory execution by a robotic arm. The system was hypothesized to achieve a targeting error of <5 mm without significant influence from variations in angulation or depth.

MATERIALS AND METHODS

An experimental study was conducted using a robotic system (Automated Needle Targeting device for CT [ANT-C]) for needle insertions into a phantom model on both moving patient table and moving gantry CT scanners. Eight spherical markers were registered as targets for 90 insertions at different trajectories. After a single ANT-C registration, the closed-loop software targeted multiple markers via the insertion of robotically aligned 18-gauge needles. Accuracy (distance from the needle tip to the target) was assessed by postinsertion CT scans. Similar procedures were repeated to guide 10 needle insertions into a porcine lung. A regression analysis was performed to test the effect of needle angulation and insertion depth on the accuracy of insertion.

RESULTS

In the phantom model, all needle insertions (median trajectory depth, 64.8 mm; range, 46.1-153 mm) were successfully performed in single attempts. The overall accuracy was 1.36 mm ± 0.53, which did not differ between the 2 types of CT scanners (1.39 mm ± 0.54 [moving patient table CT] vs 1.33 mm ± 0.52 [moving gantry CT]; P = .54) and was not significantly affected by the needle angulation and insertion depth. The accuracy for the porcine model was 9.09 mm ± 4.21.

CONCLUSIONS

Robot-assisted needle insertion using the ANT-C robotic device was feasible and accurate for targeting multiple markers in a phantom model.

A filament 3D printing approach for CT-compatible bone tissues replication

PURPOSE

The aim of this study is the development of a methodology for manufacturing 3D printed anthropomorphic structures, which mimic the X-ray properties of the human bone tissue.

METHODS

A mixing approach of two different materials is proposed for the fabrication of a radiologically equivalent hip bone for an anthropomorphic abdominal phantom. The materials employed for the phantom were polylactic acid (PLA) and Stonefil, while a custom-made dual motor filament extrusion setup and a custom-made software associating medical images directly with the 3D printing process were employed.

RESULTS

Three phantoms representing the hip bone were 3D printed utilizing two filaments under three different printing scenarios. The phantoms are based on a patient's abdominal CT scan images. Histograms of CT scans of the printed hip bone phantoms were calculated and compared to the original patient's hip bone histogram, demonstrating that a constant mixing composition of 30% Stonefil and 70% PLA with 0.0375 extrusion rate per voxel (93.75% flow for fulfilling a single voxel) for the cancellous bone, and using 100% Stonefil with 0.04 extrusion rate per voxel (100% flow) for the cortical bone results in a realistic anatomy replication of the hip bone. Reproduced HU varied between 700 and 800, which are close to those of the hip bone.

CONCLUSIONS

The study demonstrated that it is possible to mix two different filaments in real-time during the printing process to obtain phantoms with realistic and radiographically bone tissue equivalent attenuation. The results will be explored for manufacturing a CT-compatible abdominal phantom.

3D printing methods for radiological anthropomorphic phantoms

Three dimensional (3D) printing technology has been widely evaluated for the fabrication of various anthropomorphic phantoms during the last couple of decades. The demand for such high quality phantoms is constantly rising and gaining an ever-increasing interest. Although, in a short time 3D printing technology provided phantoms with more realistic features when compared to the previous conventional methods, there are still several aspects to be explored. One of these aspects is the further development of the current 3D printing methods and software devoted to radiological applications. The current 3D printing software and methods usually employ 3D models, while the direct association of medical images with the 3D printing process is needed in order to provide results of higher accuracy and closer to the actual tissues' texture. Another aspect of high importance is the development of suitable printing materials. Ideally, those materials should be able to emulate the entire range of soft and bone tissues, while still matching the human's anatomy. Five types of 3D printing methods have been mainly investigated so far: (a) solidification of photo-curing materials; (b) deposition of melted plastic materials; (c) printing paper-based phantoms with radiopaque ink; (d) melting or binding plastic powder; and (e) bio-printing. From the first and second category, polymer jetting technology and fused filament fabrication (FFF), also known as fused deposition modelling (FDM), are the most promising technologies for the fulfilment of the requirements of realistic and radiologically equivalent anthropomorphic phantoms. Another interesting approach is the fabrication of radiopaque paper-based phantoms using inkjet printers. Although, this may provide phantoms of high accuracy, the utilized materials during the fabrication process are restricted to inks doped with various contrast materials. A similar condition applies to the polymer jetting technology, which despite being quite fast and very accurate, the utilized materials are restricted to those capable of polymerization. The situation is better for FFF/FDM 3D printers, since various compositions of plastic filaments with external substances can be produced conveniently. Although, the speed and accuracy of this 3D printing method are lower compared to the others, the relatively low-cost, constantly improving resolution, sufficient printing volume and plethora of materials are quite promising for the creation of human size heterogeneous phantoms and their adaptation to the treatment procedures of patients in the current health systems.

Puncture accuracy of an optical tracked robotic aiming device-a phantom study

OBJECTIVES

To evaluate the targeting accuracy of stereotactic punctures based on a hybrid robotic device in combination with optical tracking-a phantom study.

METHODS

CT data sets of a gelatin-filled plexiglass phantom with 1-, 3-, and 5-mm slice thickness were acquired. An optical navigation device served for planning of a total of 150 needle trajectories. All punctures were carried out semi-automatically with help of the trackable iSYS-1 robotic device. Conically shaped targets inside the phantom were punctured using Kirschner wires. Up to 8 K-wires were positioned sequentially based on the same planning CT and placement accuracy was assessed by taking control CTs and measuring the Euclidean (ED) and normal distances (NDs) between the wire and the entry and target point.

RESULTS

Using the StealthStation S7, the accomplished mean ND at the target for the 1-mm, 3-mm, and 5-mm slice thickness was 0.89 mm (SD ± 0.42), 0.93 mm (SD ± 0.45), and 0.73 mm (SD ± 0.50), respectively. The corresponding mean ED was 1.61 mm (SD ± 0.36), 2.04 mm (SD ± 0.59), and 1.76 mm (SD ± 0.45). The mean duration of the total procedure was 27.9 min, including image acquisition, trajectory planning, registration, placement of 8 wires, and the control-CT.

CONCLUSIONS

The optically tracked iSYS-1 robot allows for precise punctures in a phantom. The StealthStation S7 provided acceptable results and may be helpful for interventions in difficult anatomical regions and for those requiring complex multi-angle trajectories. In combination with our optical navigation tool, the trackable robot unit allows to cover a large treatment field and the compact design facilitates placement of needle-like instruments.

KEY POINTS

• The use of a robotic targeting device in combination with optical tracking (hybrid system) allows for accurate placement of needle-like instruments without repeated control imaging. • The compact robotic positioning unit in combination with a camera for optical tracking facilitates sequential placement of multiple K-wires in a large treatment volume.

A coordinate positioning puncture method under robot-assisted CT-guidance: phantom and animal experiments

PURPOSE

To evaluate the accuracy of the robot-assisted computed tomography (CT)-guided coordinate positioning puncture method by phantom and animal experiments.

MATERIAL AND METHODS

In the phantom experiment, seven robot-assisted punctures were made to evaluate the accuracy of the method. In the animal experiment, 18 punctures (nine robotic and nine manual) were made in the livers of nine rabbits. The indicators, such as needle-tract length, angle deviation, puncture accuracy, number of scans required, and radiation exposure dose were compared between manual and robotic punctures. The paired-samples t-test was used for analysis.

RESULTS

In the phantom experiment, the mean accuracy of seven punctures was 2.67 mm. In the animal experiment, there was no significant difference in needle-tract length (32.58 mm vs. 34.04 mm, p = .606), angle deviation (17.21° vs. 21.23° p = .557) and puncture accuracy (8.42 vs. 8.77 mm, p = .851) between the two groups. However, the number CT scans required (2.44 vs. 3.33, p = .002), and the radiation exposure dose (772.98 vs. 1077.89 mGy/cm, p = .003) were lower in the robot group than in the manual group.

CONCLUSIONS

The coordinate positioning puncture method under robot-assisted CT-guidance can reach an accuracy that is comparable to that of the traditional manual CT-guided puncture method and with fewer CT scanning times accompanied with a lower radiation dosage.

Robotic Tissue Sampling for Safe Post-Mortem Biopsy in Infectious Corpses

In pathology and legal medicine, the histopathological and microbiological analysis of tissue samples from infected deceased is a valuable information for developing treatment strategies during a pandemic such as COVID-19. However, a conventional autopsy carries the risk of disease transmission and may be rejected by relatives. We propose minimally invasive biopsy with robot assistance under CT guidance to minimize the risk of disease transmission during tissue sampling and to improve accuracy. A flexible robotic system for biopsy sampling is presented, which is applied to human corpses placed inside protective body bags. An automatic planning and decision system estimates optimal insertion point. Heat maps projected onto the segmented skin visualize the distance and angle of insertions and estimate the minimum cost of a puncture while avoiding bone collisions. Further, we test multiple insertion paths concerning feasibility and collisions. A custom end effector is designed for inserting needles and extracting tissue samples under robotic guidance. Our robotic post-mortem biopsy (RPMB) system is evaluated in a study during the COVID-19 pandemic on 20 corpses and 10 tissue targets, 5 of them being infected with SARS-CoV-2. The mean planning time including robot path planning is 5.72±167s. Mean needle placement accuracy is 7.19± 422mm.

Fluoroscopy-guided robotic biopsy intervention system

Fluoroscopy-guided percutaneous biopsy interventions are mostly performed with traditional free-hand technique. The practical experience of the surgeon influences the duration of the intervention and the radiation exposure for patients and him-/herself. Especially when the placement of heavy and long instruments in double oblique angles is required, manual techniques reach their technical limitations very fast. The system presented herein automatizes the needle positioning using only two 2D scans while the robotic platform guides the intervention. These two images were used to plan the needle pathway and to estimate the pose of the robot using a custom-made end-effector with embedded registration fiducials. The estimated pose was subsequently used to transfer the planed needle path to the robot’s coordinate system and finally to compute the movement parameters in order to align the robot with this plan. To evaluate the system, two phantoms with 11 different targets on it were developed. The targets were punctured, and the application accuracy was measured quantitatively. The solution achieved sub-millimetric accuracy for needle placement (min. 0.23, max. 1.04 in mm). Our approach combines the advantages of fluoroscopic imaging and ensures automatic needle alignment with highly reduced X-ray radiation. The proposed system shows promising potential to be a guidance platform that is easy to combine with available fluoroscopic imaging systems and provides valuable help to the physician in more difficult interventions.

Experimental study of the optimum puncture pattern of robot-assisted needle insertion into hyperelastic materials

The robot-assisted insertion surgery plays a crucial role in biopsy and therapy. This study focuses on determining the optimum puncture pattern for robot-assisted insertion, aiming at the matching problem of needle insertion parameters, thereby to reduce the pain for patients and to improve the reachability to the lesion point. First, a 6-degrees of freedom (DOFs) Computed Tomography (CT)-guided surgical robotic system for minimally invasive percutaneous lung is developed and used to perform puncture experiments. The effects of four main insertion factors on the robotic puncture are verified by designing the orthogonal test, where the inserting object is the artificial skin-like specimen with high transparent property and a digital image processing method is used to analyze the needle tip deflection. Next, the various phases of puncture process are divided and analyzed in detail in view of the tissue deformation and puncture force. Then, short discussion on the comparison of puncture force with different effect factors for the same beveled needle is presented. The same pattern can be observed for all of the cases. Finally, based on the experimental data, the formulations of the puncture force and needle deflection which depends on Gauge size, insertion velocity, insertion angle, and insertion depth are developed using the multiple regression method, which can be used to get an optimum puncture pattern under the constrains of minimum peak force and minimum needle tip deflection. The developed models have the effectiveness and applicability on determining the optimum puncture pattern for one puncture event, and which can also provide insights useful for the setting of insertion parameters in clinical practice.

Lesion positioning method of a CT-guided surgical robotic system for minimally invasive percutaneous lung

BACKGROUND

Robot-assisted puncture has gradually attracted more attention and practical clinical application. The lesion positioning and the needle positioning are the basis to ensure the accuracy of puncture and the key techniques in insertion operation.

METHODS

A lesion positioning method is established which is realized only by the robot-CT system without using external positioning system, and an omnidirectional needle positioning method is also developed and realized by using VRCM, in order to make the puncture needle always keep pointing to the lesion point. A CT-guided surgical robotic system used for minimally invasive percutaneous lung is designed and the physical prototype is manufactured, to perform in-vitro experiments, thereby to validate the effectiveness of the lesion positioning method and the feasibility of omnidirectional needle positioning method.

RESULTS

The accuracy of established lesion positioning method based on three non-collinear markers is within 3 mm, which is similar to that of the least squares method based on the five non-coplanar markers, but the positioning efficiency can be improved by about 40%, and the non-collinearity of markers is easier to be satisfied than non-coplanarity in practical applications. The average calculation error of the established positioning method is 0.997 mm. Moreover, the omnidirectional positioning of the puncture needle under the designed surgical robot is feasible.

CONCLUSIONS

The designed surgical robot has good control accuracy and it can satisfy the requirements for use. The established lesion positioning method can provide a good precision basis for robot-assisted puncture surgery. The suitable insertion point and insertion posture can be determined by the developed omnidirectional needle positioning method. This study can provide theoretical reference for further study of path planning or autonomous positioning.

Prospect of robotic assistance for fully automated brachytherapy seed placement into skull base: Experimental validation in phantom and cadaver

BACKGROUND AND PURPOSE

To investigate the feasibility and accuracy of robot-assisted brachytherapy for skull base tumours.

MATERIAL AND METHODS

A custom robot system was tested on both phantom and cadaveric specimen. Cone beam CT (CBCT) images were transferred to the graphical user interface (GUI) for planning trajectories and the data were sent to the robot control unit. Following registration, the puncture needle was inserted into the target by the robot under navigation guidance, and seeds were implanted. Placement error was instantly displayed on the GUI; the result was verified after postoperative image scanning.

RESULTS

A total of 150 seeds (100 for phantom experiments, 50 for cadaveric studies) were deposited by the robot system. In phantom experiments the mean placement error was 0.57 ± 0.21 mm (measured by the navigation system) vs. 1.41 ± 0.38 mm (measured by image fusion) (p < 0.001); in cadaveric studies the corresponding figures were 0.60 ± 0.30 mm vs. 2.48 ± 0.32 mm (p < 0.001). There was no significant difference for comparison of accuracy test in phantom experiments (p = 0.173) as well as in cadaveric studies (p = 0.354). Accuracy was better in the phantom experiment than in cadaveric studies (p < 0.001).

CONCLUSIONS

The performance of robot-assisted skull base brachytherapy is feasible and accurate. Dosimetric coverage will need to be demonstrated in further studies.

Robotic CT-guided out-of-plane needle insertion: comparison of angle accuracy with manual insertion in phantom and measurement of distance accuracy in animals

Objectives

To evaluate the accuracy of robotic CT-guided out-of-plane needle insertion in phantom and animal experiments.

Methods

A robotic system (Zerobot), developed at our institution, was used for needle insertion. In the phantom experiment, 12 robotic needle insertions into a phantom at various angles in the XY and YZ planes were performed, and the same insertions were manually performed freehand, as well as guided by a smartphone application (SmartPuncture). Angle errors were compared between the robotic and smartphone-guided manual insertions using Student’s t test. In the animal experiment, 6 robotic out-of-plane needle insertions toward targets of 1.0 mm in diameter placed in the kidneys and hip muscles of swine were performed, each with and without adjustment of needle orientation based on reconstructed CT images during insertion. Distance accuracy was calculated as the distance between the needle tip and the target center.

Results

In the phantom experiment, the mean angle errors of the robotic, freehand manual, and smartphone-guided manual insertions were 0.4°, 7.0°, and 3.7° in the XY plane and 0.6°, 6.3°, and 0.6° in the YZ plane, respectively. Robotic insertions in the XY plane were significantly (p < 0.001) more accurate than smartphone-guided insertions. In the animal experiment, the overall mean distance accuracy of robotic insertions with and without adjustment of needle orientation was 2.5 mm and 5.0 mm, respectively.

Conclusion

Robotic CT-guided out-of-plane needle insertions were more accurate than smartphone-guided manual insertions in the phantom and were also accurate in the in vivo procedure, particularly with adjustment during insertion.

Key Points

• Out-of-plane needle insertions performed using our robot were more accurate than smartphone-guided manual insertions in the phantom experiment and were also accurate in the in vivo procedure.

• In the phantom experiment, the mean angle errors of the robotic and smartphone-guided manual out-of-plane needle insertions were 0.4° and 3.7° in the XY plane (p < 0.001) and 0.6° and 0.6° in the YZ plane (p = 0.65), respectively.

• In the animal experiment, the overall mean distance accuracies of the robotic out-of-plane needle insertions with and without adjustments of needle orientation during insertion were 2.5 mm and 5.0 mm, respectively.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06477-1) contains supplementary material, which is available to authorized users.

CIGuide: in situ augmented reality laser guidance

PURPOSE : A robotic intraoperative laser guidance system with hybrid optic-magnetic tracking for skull base surgery is presented. It provides in situ augmented reality guidance for microscopic interventions at the lateral skull base with minimal mental and workload overhead on surgeons working without a monitor and dedicated pointing tools. METHODS : Three components were developed: a registration tool (Rhinospider), a hybrid magneto-optic-tracked robotic feedback control scheme and a modified robotic end-effector. Rhinospider optimizes registration of patient and preoperative CT data by excluding user errors in fiducial localization with magnetic tracking. The hybrid controller uses an integrated microscope HD camera for robotic control with a guidance beam shining on a dual plate setup avoiding magnetic field distortions. A robotic needle insertion platform (iSYS Medizintechnik GmbH, Austria) was modified to position a laser beam with high precision in a surgical scene compatible to microscopic surgery. RESULTS : System accuracy was evaluated quantitatively at various target positions on a phantom. The accuracy found is 1.2 mm ± 0.5 mm. Errors are primarily due to magnetic tracking. This application accuracy seems suitable for most surgical procedures in the lateral skull base. The system was evaluated quantitatively during a mastoidectomy of an anatomic head specimen and was judged useful by the surgeon. CONCLUSION : A hybrid robotic laser guidance system with direct visual feedback is proposed for navigated drilling and intraoperative structure localization. The system provides visual cues directly on/in the patient anatomy, reducing the standard limitations of AR visualizations like depth perception. The custom- built end-effector for the iSYS robot is transparent to using surgical microscopes and compatible with magnetic tracking. The cadaver experiment showed that guidance was accurate and that the end-effector is unobtrusive. This laser guidance has potential to aid the surgeon in finding the optimal mastoidectomy trajectory in more difficult interventions.

Design and control of a MRI-compatible pneumatic needle puncture robot

Percutaneous needle puncture operation is widely used in the image-guided interventions, including biopsy and ablation. MRI guidance has the advantages of high-resolution soft tissue imaging and thermal monitoring during energy-based ablation. This paper proposes the design of a 5-DOF pneumatic needle puncture robot, with all the cylinders, sensors and structure material MRI-compatible. Also, a hybrid fuzzy-PID controller is designed for the pneumatic driven system to adjust the PID parameters adaptively. The experiment validation result shows that, compared with the traditional fix-parameter PID control, the proposed hybrid fuzzy-PID control has no overshoot, and the settle time/steady state error remains low even with increasing load. This proves that the hybrid fuzzy-PID control strategy can increases the positioning accuracy and robustness of the pneumatic driven needle puncture robot, which is significant for the safety of percutaneous needle puncture operation.

Patient-specific templates for image-guided intervention - a phantom study

Purpose: To evaluate the in vitro accuracy of a new device and method for simultaneous stereotactic CT-guided punctures.Material and methods: 240 needle paths were planned in 1 mm, 1.5 mm and 3 mm slice thickness with a custom-designed software. The data were transferred to a three-axis tabletop CNC machine that then drilled the hole pattern for the needles into square plastic plates. Kirschner wires were slid through the holes of the two parallel fixed plates to aim at the chosen targets inside the phantom. The accuracy was calculated by taking control CTs and measuring the Euclidean distance and the normal distance between the wire and the entry and target point.Results: The mean Euclidean distance of the wire tip to the target for the 1 mm, 1.5mm and 3 mm slice thickness were 2.5 mm (SD ± 0.64), 2.71mm (SD ± 0.78) and 2.8 mm (SD ± 1.0). The mean normal distance was 1.42 mm (SD ± 0.65), 1.43mm (SD ± 0.75) and 1.9 mm (SD ± 1.1), respectively.Conclusion: The system yields satisfactory accuracy comparable to other image-guided intervention systems. Involuntary movements of the patient need to be taken into account in a clinical setting.

Origami Lesion-Targeting Device for CT-Guided Interventions

The objective of this study is to preliminarily evaluate a lesion-targeting device for CT-guided interventions. The device is created by laser cutting the structure from a sheet of medical grade paperboard, 3D printing two radiocontrast agent grids onto the surface and folding the structure into a rectangular prism with a viewing window. An abdominal imaging phantom was used to evaluate the device through CT imaging and the targeting of lesions for needle insertion. The lesion-targeting trials resulted in a mean targeting error of 2.53 mm (SD 0.59 mm, n = 30). The device is rigid enough to adequately support standard biopsy needles, and it attaches to the patient, reducing the risk of tissue laceration by needles held rigidly in place by an external manipulator. Additional advantages include adequate support for the insertion of multiple surgical tools at once for procedures such as composite ablation and the potential to guide off-axial needle insertion. The low-cost and disposability of the device make it well-suited for the minimally invasive image-guided therapy environment.

Robotic versus Freehand Needle Positioning in CT-guided Ablation of Liver Tumors: A Randomized Controlled Trial

Purpose To compare the accuracy of freehand versus robotic antenna placement in CT-guided microwave ablation (MWA) of liver tumors. Materials and Methods This study was conducted as a prospective single-center nonblinded randomized controlled trial (Netherlands Trial Registry, NTR6023). Eligible study participants had undergone clinically indicated CT-guided MWA of liver tumors and were able to receive a CT contrast agent. Randomization was performed per tumor after identification on contrast material-enhanced CT images. The primary outcome was the number of antenna repositionings, which was compared by using the Mann-Whitney U test. Secondary outcomes were lateral targeting error stratified by in-plane and out-of-plane targets and targeting time. Results Between February 14 and November 12, 2017, 31 participants with a mean age of 63 years (range, 25-88 years) were included: 17 women (mean age, 57 years; range, 25-77 years) and 14 men (mean age, 70 years; range, 52-88 years). The freehand study arm consisted of 19 participants, while the robotic study arm consisted of 18 participants; six participants with multiple tumors were included in both arms. Forty-seven tumors were assessed; five tumors were excluded from the analysis because of technical limitations. In the robotic arm, no antenna repositioning was required. In the freehand arm, a median of one repositioning was required (range, zero to seven repositionings; P < .001). For out-of-plane targets, lateral targeting error was 10.1 mm ± 4.0 and 5.9 mm ± 2.9 (P = .007) for freehand and robotic procedures, respectively, and for in-plane targets, lateral targeting error was 6.2 mm ± 2.7 and 7.7 mm ± 5.9, respectively (P = .51). Mean targeting time was 19 minutes (range, 8-55 minutes) and 36 minutes (range, 3-70 minutes; P = .001) for freehand and robotic procedures, respectively. Conclusion Robotic antenna guidance reduces the need for antenna repositioning in microwave ablation to accurately target liver tumors and increases accuracy for out-of-plane targets. However, targeting time was greater with robotic guidance than with freehand targeting. © RSNA, 2019.

Robotic Insertion of Various Ablation Needles Under Computed Tomography Guidance: Accuracy in Animal Experiments

OBJECTIVE

To evaluate the accuracy of robotic insertion of various ablation needles at various locations under computed tomography (CT) guidance in swine.

MATERIALS AND METHODS

The robot was used for CT-guided insertion of four ablation needles, namely a single internally cooled radiofrequency ablation (RFA) needle (Cool-tip), a multi-tined expandable RFA needle (LeVeen), a cryoablation needle (IceRod), and an internally cooled microwave ablation needle (Emprint). One author remotely operated the robot with the operation interface in order to orient and insert the needles under CT guidance. Five insertions of each type of ablation needle towards 1.0-mm targets in the liver, kidney, lung, and hip muscle were attempted on the plane of an axial CT image in six swine. Accuracy of needle insertion was evaluated as the three-dimensional length between the target centre and needle tip. The accuracy of needle insertion was compared according to the type of needle used and the location using one-way analysis of variance.

RESULTS

The overall mean accuracy of all four needles in all four locations was 2.8 mm. The mean accuracy of insertion of the Cool-tip needle, LeVeen needle, IceRod needle, and Emprint needle was 2.8 mm, 3.1 mm, 2.5 mm, and 2.7 mm, respectively. The mean accuracy of insertion into the liver, kidney, lung, and hip muscle was 2.7 mm, 2.9 mm, 2.9 mm, and 2.5 mm, respectively. There was no significant difference in insertion accuracy among the needles (P = .38) or the locations (P = .53).

CONCLUSION

Robotic insertion of various ablation needles under CT guidance was accurate regardless of type of needle or location in swine.

Laser Generated Leaky Acoustic Waves for Needle Visualization

Ultrasound (US)-guided needle operation is usually used to visualize both tissue and needle position such as tissue biopsy and localized drug delivery. However, the transducer-needle orientation is limited due to reflection of the acoustic waves. We proposed a leaky acoustic wave method to visualize the needle position and orientation. Laser pulses are emitted on top of the needle to generate acoustic waves; then, these acoustic waves propagate along the needle surface. Leaky wave signals are detected by the US array transducer. The needle position can be calculated by phase velocities of two different wave modes and their corresponding emission angles. In our experiments, a series of needles was inserted into a tissue mimicking phantom and porcine tissue to evaluate the accuracy of the proposed method. The results show that the detection depth is up to 51 mm and the insertion angle is up to 40° with needles of different diameters. It is demonstrated that the proposed approach outperforms the conventional B-mode US-guided needle operation in terms of the detection range while achieving similar accuracy. The proposed method reveals the potentials for further clinical applications.

Validation of a CT-guided intervention robot for biopsy and radiofrequency ablation: experimental study with an abdominal phantom

PURPOSE

We aimed to evaluate the accuracy of a needle-placement robot for biopsy and radiofrequency ablation on an abdominal phantom.

METHODS

A master-slave robotic system has been developed that includes a needle-path planning system and a needle-inserting robot arm with computed tomography (CT) and CT fluoroscopy guidance. For evaluation of its accuracy in needle placement, a commercially available abdominal phantom (Model 057A; CIRS Inc.) was used. The liver part of the phantom contains multiple spherical simulated tumors of three different size spheres. Various needle insertion trials were performed in the transverse plane and caudocranial plane two nodule sizes (10 mm and 20 mm in diameter) to test the reliability of this robot. To assess accuracy, a CT scan was performed after each trial with the needle in situ.

RESULTS

The overall error was 2 mm (0-2.6 mm), which was calculated as the distance from the planned trajectory before insertion to the actual needle trajectory after insertion. The standard deviations of the insertions on two nodules (10 mm and 20 mm in diameter) were 0.5 mm and 0.2 mm, respectively.

CONCLUSION

The CT-compatible needle placement robot for biopsy and radiofrequency ablation shows relatively acceptable accuracy and could be used for radiofrequency ablation of nodules ≥10 mm under CT fluoroscopy guidance.

AngleNav: MEMS Tracker to Facilitate CT-Guided Puncture

As a low-cost needle navigation system, AngleNav may be used to improve the accuracy, speed, and ease of CT-guided needle punctures. The AngleNav hardware includes a wireless device with a microelectromechanical (MEMS) tracker that can be attached to any standard needle. The physician defines the target, desired needle path and skin entry point on a CT slice image. The accuracy of AngleNav was first tested in a 3D-printed calibration platform in a benchtop setting. An abdominal phantom study was then performed in a CT scanner to validate the accuracy of the device's angular measurement. Finally, an in vivo swine study was performed to guide the needle towards liver targets (n = 8). CT scans of the targets were used to quantify the angular errors and needle tip-to-targeting distance errors between the planned needle path and the final needle position. The MEMS tracker showed a mean angular error of 0.01° with a standard deviation (SD) of 0.62° in the benchtop setting. The abdominal phantom test showed a mean angular error of 0.87° with an SD of 1.19° and a mean tip-to-target distance error of 4.89 mm with an SD of 1.57 mm. The animal experiment resulted in a mean angular error of 6.6° with an SD of 1.9° and a mean tip-to-target distance error of 8.7 mm with an SD of 3.1 mm. These results demonstrated the feasibility of AngleNav for CT-guided interventional workflow. The angular and distance errors were reduced by 64.4 and 54.8% respectively if using AngleNav instead of freehand insertion, with a limited number of operators. AngleNav assisted the physicians to deliver accurate needle insertion during CT-guided intervention. The device could potentially reduce the learning curve for physicians to perform CT-guided needle targeting.

Performance of Robotic Assistance for Skull Base Biopsy: A Phantom Study

Objectives  This study aims to evaluate the feasibility of a custom robot system guided by optical cone beam computed tomography (CBCT)-based navigation for skull base biopsy. Design  An accuracy study was conducted. Setting  Platform for navigation and robot-aided surgery technology. Participants  Phantom skull. Main Outcome Measures  The primary outcome measure was to investigate the accuracy of robot-assisted needle biopsy for skull base tumors. A 14-gauge needle was automatically inserted by the five degrees of freedom robot into the intended target, guided by optical navigation. The result was displayed on the graphical user interface after matrix transformation. Postoperative image scanning was performed, and the result was verified with image fusion. Results  All 20 interventions were successfully performed. The mean deviation of the needle tip was 0.56 ± 0.22 mm (measured by the navigation system) versus 1.73 ± 0.60 mm (measured by image fusion) ( p  < 0.05). The mean insertion depth was 52.3 mm (range: 49.7-55.2 mm). The mean angular deviations off the x-axis, y-axis, and z-axis were 1.51 ± 0.67, 2.33 ± 1.65, and 1.47 ± 1.16 degrees, respectively. Conclusions  The experimental results show the robot system is efficient, reliable, and safe. The navigation accuracy is a significant factor in robotic procedures.

Real-time respiratory phase matching between 2D fluoroscopic images and 3D CT images for precise percutaneous lung biopsy

PURPOSE

A 3D CT image is used along with real-time 2D fluoroscopic images in the state-of-the-art cone-beam CT system to guide percutaneous lung biopsy (PLB). To improve the guiding accuracy by compensating for respiratory motion, we propose an algorithm for real-time matching of 2D fluoroscopic images to multiple 3D CT images of different respiratory phases that is robust to the small movement and deformation due to cardiac motion.

METHODS

Based on the transformations obtained from nonrigid registration between two 3D CT images acquired at expiratory and inspiratory phases, we first generate sequential 3D CT images (or a 4D CT image) and the corresponding 2D digitally reconstructed radiographs (DRRs) of vessels. We then determine 3D CT images corresponding to each real-time 2D fluoroscopic image, by matching the 2D fluoroscopic image to a 2D DRR.

RESULTS

Quantitative evaluations performed with 20 clinical datasets show that registration errors of anatomical features between a 2D fluoroscopic image and its matched 2D DRR are less than 3 mm on average. Registration errors of a target lesion are determined to be roughly 3 mm on average for 10 datasets.

CONCLUSIONS

We propose a real-time matching algorithm to compensate for respiratory motion between a 2D fluoroscopic image and 3D CT images of the lung, regardless of cardiac motion, based on a newly improved matching measure. The proposed algorithm can improve the accuracy of a guiding system for the PLB by providing 3D images precisely registered to 2D fluoroscopic images in real-time, without time-consuming respiratory-gated or cardiac-gated CT images.

Endpoint Accuracy in Manual Control of a Steerable Needle

PURPOSE

To study the ability of a human operator to manually correct for errors in the needle insertion path without partial withdrawal of the needle by means of an active, tip-articulated steerable needle.

MATERIALS AND METHODS

The needle is composed of a 1.32-mm outer-diameter cannula, with a flexure joint near the tip, and a retractable stylet. The bending stiffness of the needle resembles that of a 20-gauge hypodermic needle. The needle functionality was evaluated in manual insertions by steering to predefined targets and a lateral displacement of 20 mm from the straight insertion line. Steering tasks were conducted in 5 directions and 2 tissue simulants under image guidance from a camera. The repeatability in instrument actuations was assessed during 100 mm deep automated insertions with a linear motor. In addition to tip position, tip angles were tracked during the insertions.

RESULTS

The targeting error (mean absolute error ± standard deviation) during manual steering to 5 different targets in stiff tissue was 0.5 mm ± 1.1. This variability in manual tip placement (1.1 mm) was less than the variability among automated insertions (1.4 mm) in the same tissue type. An increased tissue stiffness resulted in an increased lateral tip displacement. The tip angle was directly controlled by the user interface, and remained unaffected by the tissue stiffness.

CONCLUSIONS

This study demonstrates the ability to manually steer needles to predefined target locations under image guidance.

Laser-assisted flat-detector CT-guided intracranial access

PURPOSE

Flat-detector CT can be integrated with C-arm fluoroscopy for CT-guided neurosurgical and endovascular procedures. We studied the accuracy of this technique with laser assistance in targeting intracranial lesions in a cranial model.

METHODS

An acrylic scale-model skull containing foam parenchyma was embedded with 2.16-mm-diameter targets. A flat-detector CT was acquired and registered to the skull's position. Ten targets were accessed with biopsy needles under fluoroscopic guidance, flat-detector CT overlay, and laser assistance. Accuracy was measured from the needle tip to the target center using flat-detector CT.

RESULTS

Ten targets were accessed successfully using XperGuide software. Needles were placed within 1.30 [Formula: see text] 0.63 mm of target isocenter. Accuracy did not vary by entry site, operator, location, or lesion depth.

CONCLUSIONS

Laser-assisted flat-detector CT-guided targeting of all intracranial targets was successful with excellent accuracy. This technique can be applied to other minimally invasive neurosurgical procedures.