Accuracy and speed of robotic assisted needle interventions using a modern cone beam computed tomography intervention suite: a phantom study

Robot-Assisted CT-Guided Biopsy with an Artificial Intelligence-Based Needle-Path Generator: An Experimental Evaluation Using a Phantom Model

PURPOSE

To investigate the feasibility of a robotic system with artificial intelligence-based lesion detection and path planning for computed tomography (CT)-guided biopsy compared with the conventional freehand technique.

MATERIALS AND METHODS

Eight nodules within an abdominal phantom, incorporating the simulated vertebrae and ribs, were designated as targets. A robotic system was used for lesion detection, trajectory generation, and needle holder positioning. Four interventional radiologists with more than 5 years of experience and 4 with 5 years of experience or less performed 96 robot-assisted insertions encompassing both in-plane and out-of-plane trajectories. Additionally, 32 CT fluoroscopy single-rotation scan-guided freehand needle insertions were performed along the in-plane trajectories. The 3-dimensional (3D), lateral, depth deviations, and insertion time were quantified using post-needle insertion CT scans. Statistical analysis was performed using the unpaired t-test or 1-way analysis of variance, with a significance level of P < .05.

RESULTS

The system detected all target lesions and generated appropriate needle paths. Robot-assisted insertions exhibited significantly smaller 3D and depth deviations than freehand insertions (3.8 mm ± 1.3 vs 4.7 mm ± 1.6, P = .001, and 1.8 mm ± 1.2 vs 2.6 mm ± 1.8, P = .005, respectively). No significant difference was observed in lateral deviations (3.0 mm ± 1.5 vs 3.5 mm ± 1.5, P = .118). Robotic assistance significantly reduced insertion time compared with freehand insertion (17.3 s ± 7.8 vs 78.6 s ± 38.1, P < .001). The same trends were observed between the 2 groups of radiologists.

CONCLUSIONS

The robotic system has the potential to shorten puncture time while maintaining sufficient accuracy in CT-guided procedures.

The Role and Future of Artificial Intelligence in Robotic Image-Guided Interventions

Artificial intelligence and robotics are transforming interventional radiology, driven by advancements in computer vision, robotics and procedural automation. Historically focused on diagnostics, AI now also enhances procedural capabilities in IR, enabling future robotic systems to handle complex tasks such as catheter manipulation or needle placement with increasing precision and reliability. Early robotic systems in IR demonstrated improved accuracy in both vascular and percutaneous interventions, though none were equipped with automatic decision-making. This review tends to show the potential in improving procedural outcomes with AI for robotics, though challenges remain. Techniques like reinforcement learning and haptic vision are under investigation to address several issues, training robots to adapt based on real-time feedback from the environment. As AI-driven robotics evolve, IR could shift towards a model where human expertise oversees the technology rather than performs the intervention itself.

Image Guided Percutaneous Robotic Interventions for Solid Organs

Robotic systems for minimally invasive procedures, particularly in interventional oncology, have advanced significantly, especially for percutaneous interventions guided by CT, Cone-beam CT, and MRI. These systems, which include needle-guiding and needle-driving robots, enhance the precision of procedures like biopsy and tumor ablation. Needle-guiding robots plan and align the needle, while needle-driving robots autonomously advance it, improving needle placement accuracy, enabling out-of-plane insertion, and reducing radiation exposure. These robotic systems offer key clinical benefits, such as stable needle guidance for challenging angulated approaches and better access to lesions in confined spaces, like CT or MRI gantries. They can guide the needle to the optimal region of a lesion without the need for a second contrast injection, improving both diagnosis and treatment. While many robotic systems have been developed, only a few have reached clinical use. Early studies show promising results, but concerns about increased complexity and cost remain. Further research and clinical trials are needed to fully evaluate their value, though we believe that robotic systems will play an increasingly important role in the future of image-guided interventions, particularly for challenging tumors.

Remote-Controlled and Teleoperated Systems: Taking Robotic Image Guided Interventions to the Next Stage

Remote-controlled and teleoperated robotic systems mark transformative advancements in interventional radiology (IR), with the potential to enhance precision, reduce radiation exposure, and expand access to care. By integrating robotic devices with imaging guidance, these systems enable precise instrument placement and navigation, thereby improving the efficacy and safety of minimally invasive procedures. Remote-controlled and teleoperated robotic systems-operated by clinicians using control interfaces from within or adjacent to the procedure room-are being adopted for both percutaneous and endovascular interventions. In contrast, although their application is still experimental, teleoperation over long distances hold promise for extending IR services to medically underserved areas by enabling remote procedures. This review details the definitions and components of remote-controlled and teleoperated robotic systems in IR, examines their clinical applications in percutaneous and endovascular interventions, and discusses relevant challenges and future directions for their incorporation into IR practices.

Percutaneous Lung Biopsies With Robotic Systems: A Systematic Review of Available Clinical Solutions

Objectives: This systematic review aims to assess existing research concerning the use of robotic systems to execute percutaneous lung biopsy. Methods: A systematic review was performed and identified 4 studies involving robotic systems used for lung biopsy. Outcomes assessed were operation time, radiation dose to patients and operators, technical success rate, diagnostic yield, and complication rate. Results: One hundred and thirteen robot-guided percutaneous lung biopsies were included. Technical success and diagnostic yield were close to 100%, comparable to manual procedures. Technical accuracy, illustrated by needle positioning, showed less frequent needle adjustments in robotic guidance than in manual guidance (P < .001): 2.7 ± 2.6 (range 1-4) versus 6 ± 4 (range 2-12). Procedure time ranged from comparable to reduced by 35% on average (20.1 ± 11.3 minutes vs 31.4 ± 10.2 minutes, P = .001) compared to manual procedures. Patient irradiation ranged from comparable to reduced by an average of 40% (324 ± 114.5 mGy vs 541.2 ± 446.8 mGy, P = .001). There was no significant difference in reported complications between manual biopsy and biopsies that utilized robotic guidance. Conclusion: Robotic systems demonstrate promising results for percutaneous lung biopsy. These devices provide adequate accuracy in probe placement and could both reduce procedural duration and mitigate radiation exposure to patients and practitioners. However, this review underscores the need for larger, controlled trials to validate and extend these findings.

Contribution and advances of robotics in percutaneous oncological interventional radiology

The advent of robotic systems in interventional radiology marks a significant evolution in minimally invasive medical procedures, offering enhanced precision, safety, and efficiency. This review comprehensively analyzes the current state and applications of robotic system usage in interventional radiology, which can be particularly helpful for complex procedures and in challenging anatomical regions. Robotic systems can improve the accuracy of interventions like microwave ablation, radiofrequency ablation, and irreversible electroporation. Indeed, studies have shown a notable decrease of an average 30% in the mean deviation of probes, and a 40% lesser need for adjustments during interventions carried out with robotic assistance. Moreover, this review highlights a 35% reduction in radiation dose and a stable-to-30% reduction in operating time associated with robot-assisted procedures compared to manual methods. Additionally, the potential of robotic systems to standardize procedures and minimize complications is discussed, along with the challenges they pose, such as setup duration, organ movement, and a lack of tactile feedback. Despite these advancements, the field still grapples with a dearth of randomized controlled trials, which underscores the need for more robust evidence to validate the efficacy and safety of robotic system usage in interventional radiology.

Puncture Accuracy of Robot-Assisted CT-Based Punctures in Interventional Radiology: An Ex Vivo Study

OBJECTIVES

The purpose of this study was to assess the performance of an optically tracked robot for computed-tomography (CT)-guided needle placements in a phantom study.

METHODS

In total, 240 needle punctures were carried out with the help of an optically tracked robotic device (Micromate) based on CT image datasets at three different slice thicknesses (1, 3, and 5 mm). Conically shaped targets inside a gelatin-filled plexiglass phantom were punctured. The target positioning error between the planned and actual needle trajectory was assessed by measuring the lateral positioning error (ND) between the target and the puncture needle and the Euclidean distance (ED) between the needle tip and target in control CTs.

RESULTS

The mean ND and ED for the thinnest CT slice thickness were 1.34 mm (SD ± 0.82) and 2.1 mm (SD ± 0.75), respectively. There was no significant impact of target depth on targeting accuracy for ND (p = 0.094) or ED (p = 0.187). The mean duration for the planning of one trajectory and for needle positioning were 42 s (SD ± 4) and 64 s (SD ± 7), respectively.

CONCLUSIONS

In this ex vivo study, the robotic targeting device yielded satisfactory accuracy results at CT slice thicknesses of 1 and 3 mm. This technology may be particularly useful in interventions where the accurate placement of needle-like instruments is required.

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.

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 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.

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.

Musculoskeletal interventional oncology: current and future practices

Management of musculoskeletal (MSK) tumours has traditionally been delivered by surgeons and medical oncologists. However, in recent years, image-guided interventional oncology (IO) has significantly impacted the clinical management of MSK tumours. With the rapid evolution of relevant technologies and the expanding range of clinical indications, it is likely that the impact of IO will significantly grow and further evolve in the near future.

In this narrative review, we describe well-established and new interventional technologies that are currently integrating into the IO armamentarium available to radiologists to treat MSK tumours and illustrate new emerging IO indications for treatment.

Stereotactic Neuro-Navigation Phantom Designs: A Systematic Review

Diverse stereotactic neuro-navigation systems are used daily in neurosurgery and novel systems are continuously being developed. Prior to clinical implementation of new surgical tools, methods or instruments, in vitro experiments on phantoms should be conducted. A stereotactic neuro-navigation phantom denotes a rigid or deformable structure resembling the cranium with the intracranial area. The use of phantoms is essential for the testing of complete procedures and their workflows, as well as for the final validation of the application accuracy. The aim of this study is to provide a systematic review of stereotactic neuro-navigation phantom designs, to identify their most relevant features, and to identify methodologies for measuring the target point error, the entry point error, and the angular error (α). The literature on phantom designs used for evaluating the accuracy of stereotactic neuro-navigation systems, i.e., robotic navigation systems, stereotactic frames, frameless navigation systems, and aiming devices, was searched. Eligible articles among the articles written in English in the period 2000-2020 were identified through the electronic databases PubMed, IEEE, Web of Science, and Scopus. The majority of phantom designs presented in those articles provide a suitable methodology for measuring the target point error, while there is a lack of objective measurements of the entry point error and angular error. We identified the need for a universal phantom design, which would be compatible with most common imaging techniques (e.g., computed tomography and magnetic resonance imaging) and suitable for simultaneous measurement of the target point, entry point, and angular errors.

Preliminary clinical application of the robot-assisted CT-guided irreversible electroporation ablation for the treatment of pancreatic head carcinoma

BACKGROUND

To evaluate the feasibility and safety of a robot-guided irreversible electroporation (IRE) ablation system for the treatment of pancreatic head carcinoma.

METHODS

A total of 20 cases with pancreatic head carcinoma were divided into two groups: 11 cases in group A with manual probe placement and 9 cases in group B with robotic navigated probe placement. The two groups were compared in terms of planning time before puncture, puncture time, the total time of electrode deployment, number of scans, and punctual accuracy of the single electrode.

RESULTS

Each probe was successfully punctured, and no complications were detected. P-values were calculated for all the parameters, using the SPSS 25.0 software and the t test.

CONCLUSIONS

The new robot can reduce the total operating time as compared to the manual probe placement with the same accuracy in the IRE of pancreatic head carcinoma.

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.

Electromagnetic navigation to assist with computed tomography-guided thermal ablation of liver tumors

Purpose: To evaluate the advantages and primary technical efficacy of an electromagnetic (EM) navigation system for computed tomography (CT)-guided thermal ablation of liver tumors.Material and methods: From August 2016 to January 2018, 40 patients scheduled for CT- guided thermal ablation were prospectively enrolled and divided into two groups. Twenty patients underwent CT-guided thermal ablation with an EM navigation system (navigation group), while the other 20 patients underwent conventional CT-guided thermal ablation (control group). Data on skin punctures, instrument adjustments, puncture time to target, CT scans, CT fluoroscopy time and dose-length-product (DLP) were compared between the two groups. Any postoperative complications were recorded and the primary technical efficacy was evaluated four to six weeks after the procedure.Results: All 20 patients in the navigation group successfully underwent EM navigation. Compared to the control group, there were fewer instrument adjustments (mean 2.40 vs. 4.95; p = .003), fewer CT scans (mean 7.10 vs. 10.30; p = .006), less CT fluoroscopy time (mean 40.47 vs. 59.98 s, p = .046), and less DLP (mean 807.39 vs. 1578.67 mGy × cm; p = .001). Although not statistically significant, EM navigation resulted in fewer skin punctures (mean 1.20 vs. 1.25; p = .803) and slightly longer puncture time to target (mean 16.50 vs. 15.20 min; p = .725). No patients experienced major complications and the primary efficacy rate was 90% and 84.21% in the navigation and control groups, respectively (p = .661).Conclusions: EM navigation system optimizes the thermal ablation process and reduces radiation exposure in patients. However, further studies are warranted to determine whether an EM navigation system can improve procedure time, complication rates, and primary technical efficiacy of thermal ablation.

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 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.

Accuracy of semi-automated versus manual localisation of liver tumours in CT-guided ablation procedures

OBJECTIVES

To compare the accuracy of liver tumour localisation in intraprocedural computed tomography (CT) images of computer-based rigid registration or non-rigid registration versus mental registration performed by interventional radiologists.

METHODS

Retrospectively (2009-2017), 35 contrast-enhanced CT (CECT) images incorporating 56 tumours, acquired during CT-guided ablation procedures and their corresponding pre-procedural diagnostic CECTs were retrieved from the picture archiving and communication system (PACS). The original intraprocedural CECTs were de-enhanced to create a virtually unenhanced CT image (VUCT). Alignment of diagnostic CECTs to their corresponding intraprocedural VUCTs was performed with non-rigid or rigid registration. Mental registration was performed by four interventional radiologists. The original intraprocedural CECT served as the reference standard. Accuracy of tumour localisation was assessed with the target registration error (TRE). Statistical differences were analysed with the Wilcoxon signed-rank test.

RESULTS

Non-rigid registration failed to register two CT datasets, incorporating four tumours. In the remaining 33 datasets, non-rigid, rigid and mental registration showed a median TRE of 3.9 mm, 9.0 mm and 10.9 mm, respectively. Non-rigid registration was significantly more accurate in tumour centre localisation in comparison to rigid (p < 0.001) or mental registration (p < 0.001). Rigid registration was not statistically different from mental registration (p = 0.169). Non-rigid registration was most accurate in localising tumour centres in 42 out of 52 tumours (80.8%), while rigid and mental registration were most accurate in only seven (13.5%) and three (5.8%) tumours, respectively.

CONCLUSIONS

Computer-based non-rigid registration is statistically significantly more accurate in localising liver tumours in intraprocedural unenhanced CT images in comparison to rigid registration or interventional radiologists' mental mapping abilities.

KEY POINTS

• Computer-based non-rigid registration is better (p < 0.001) in localising target tumours prior to ablation in intraprocedural CT images in comparison to rigid registration or interventional radiologists' mental mapping abilities. • Human experts perform sub-optimal localisation of target tumours when relying solely on mental mapping during challenging CT-guided procedures. • This non-rigid registration method shows promising results as a safe alternative to intravenous contrast media in liver tumour localisation prior to ablation during CT-guided procedures.

A radiopaque 3D printed, anthropomorphic phantom for simulation of CT-guided procedures

OBJECTIVES

To develop an anthropomorphic phantom closely mimicking patient anatomy and to evaluate the phantom for the simulation of computed tomography (CT)-guided procedures.

METHODS

Patient CT images were printed with aqueous potassium iodide solution (1 g/mL) on paper. The printed paper sheets were stacked in alternation with 1-mm thick polyethylene foam layers, cut to the patient shape and glued together to create an anthropomorphic abdomen phantom. Ten interventional radiologists performed periradicular infiltration on the phantom and rated the phantom procedure regarding different aspects of suitability for simulating CT-guided procedures.

RESULTS

Radiopaque printing in combination with polyethylene foam layers achieved a phantom with detailed patient anatomy that allowed needle placement. CT-guided periradicular infiltration on the phantom was rated highly realistic for simulation of anatomy, needle navigation and overall course of the procedure. Haptics were rated as intermediately realistic. Participants strongly agreed that the phantom was suitable for training and learning purposes.

CONCLUSIONS

A radiopaque 3D printed, anthropomorphic phantom provides a realistic platform for the simulation of CT-guided procedures. Future work will focus on application for training and procedure optimisation.

KEY POINTS

• Radiopaque 3D printing combined with polyethylene foam achieves patient phantoms for CT-guided procedures. • Radiopaque 3D printed, anthropomorphic phantoms allow realistic simulation of CT-guided procedures. • Realistic visual guidance is a key aspect in simulation of CT-guided procedures. • Three-dimensional printed phantoms provide a platform for training and optimisation of CT-guided procedures.

Computed Tomography-Assisted Thoracoscopic Surgery: A Novel, Innovative Approach in Patients With Deep Intrapulmonary Lesions of Unknown Malignant Status

OBJECTIVES

Minimally invasive resection of small, deep intrapulmonary lesions can be challenging due to the difficulty of localizing them during video-assisted thoracoscopic surgery (VATS). We report our preliminary results evaluating the feasibility of an image-guided, minimally invasive, 1-stop-shop approach for the resection of small, deep intrapulmonary lesions in a hybrid operating room (OR).

MATERIALS AND METHODS

Fifteen patients (5 men, 10 women; mean age, 63 years) with a total of 16 solitary, deep intrapulmonary nodules of unknown malignant status were identified for intraoperative wire marking. Patients were placed on the operating table for resection by VATS. A marking wire was placed within the lesion under 3D laser and fluoroscopic guidance using a cone beam computed tomography system. Then, wedge resection by VATS was performed in the same setting without repositioning the patient.

RESULTS

Complete resection with adequate safety margins was confirmed for all lesions. Marking wire placement facilitated resection in 15 of 16 lesions. Eleven lesions proved to be malignant, either primary or secondary; 5 were benign. Mean lesion size was 7.7 mm; mean distance to the pleural surface was 15.1 mm (mean lesion depth-diameter ratio, 2.2). Mean procedural time for marking wire placement was 35 minutes; mean VATS duration was 36 minutes.

CONCLUSIONS

Computed tomography-assisted thoracoscopic surgery is a new, safe, and effective procedure for minimally invasive resection of small, deeply localized intrapulmonary lesions. The benefits of computed tomography-assisted thoracoscopic surgery are 1. One-stop-shop procedure, 2. Lower risk for the patient (no patient relocation, no marking wire loss), and 3. No need to coordinate scheduling between the CT room and OR.

Modelling and Experiment Based on a Navigation System for a Cranio-Maxillofacial Surgical Robot

In view of the characteristics of high risk and high accuracy in cranio-maxillofacial surgery, we present a novel surgical robot system that can be used in a variety of surgeries. The surgical robot system can assist surgeons in completing biopsy of skull base lesions, radiofrequency thermocoagulation of the trigeminal ganglion, and radioactive particle implantation of skull base malignant tumors. This paper focuses on modelling and experimental analyses of the robot system based on navigation technology. Firstly, the transformation relationship between the subsystems is realized based on the quaternion and the iterative closest point registration algorithm. The hand-eye coordination model based on optical navigation is established to control the end effector of the robot moving to the target position along the planning path. The closed-loop control method, “kinematics + optics” hybrid motion control method, is presented to improve the positioning accuracy of the system. Secondly, the accuracy of the system model was tested by model experiments. And the feasibility of the closed-loop control method was verified by comparing the positioning accuracy before and after the application of the method. Finally, the skull model experiments were performed to evaluate the function of the surgical robot system. The results validate its feasibility and are consistent with the preoperative surgical planning.

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.

Minimally invasive screw fixation of fractures in the thoracic spine: CT-controlled pre-surgical guidewire implantation in routine clinical practice

AIM

To evaluate the feasibility and accuracy of minimally invasive, transpedicular screw placement in cervicothoracic fractures with the help of computed tomography (CT)-controlled guidewires.

MATERIALS AND METHODS

Two hundred and ninety-three guidewires were inserted in 35 patients (42.9±21.2 years) under CT fluoroscopy (286 thoracic, seven cervical). There were 28 traumatic cases, three pathological fractures, three fractures due to infectious infiltrations, and one osteoporotic fracture. In 151 pedicles, screw placement was performed in the CT room. CT images were reviewed regarding accuracy and cortical violations using the popular 2 mm increment deviation classification of Gertzbein and Robbins.

RESULTS

Guidewire implantation resulted in only 28 cortical contacts. Minor encroachments of the pedicle wall by inserted screws occurred in 39.1% (59 of 151) and in 23.8% if taking unavoidable encroachments into account (30 of 59). Pedicular isthmus width correlated to cortical guidewire contacts (r=-0.449; p=0.077) and pedicle violations (all graded "A") by the inserted screws (r=-0.581; p=0.049). Total procedural duration was 138.6±44.2 minutes, representing 14.5±11.6 minutes for each pedicle, while showing a significant correlation against higher vertebral levels (r=-0.849; p=0.0002) and the occurrence of pedicle violations (r=-0.641; p=0.027).

CONCLUSIONS

The treatment of vertebral fractures with a guidewire-based pedicle screw insertion technique under CT imaging results in very high accuracy and a low complication rate.

The Use of Laser Guidance Reduces Fluoroscopy Time for C-Arm Cone-Beam Computed Tomography-Guided Biopsies

PURPOSE

When using laser guidance for cone-beam computed tomography (CBCT)-guided needle interventions, planned needle paths are visualized to the operator without the need to switch between entry- and progress-view during needle placement. The current study assesses the effect of laser guidance during CBCT-guided biopsies on fluoroscopy and procedure times.

MATERIALS AND METHODS

Prospective data from 15 CBCT-guided biopsies of 8-65 mm thoracic and abdominal lesions assisted by a ceiling-mounted laser guidance technique were compared to retrospective data of 36 performed CBCT-guided biopsies of lesions >20 mm using the freehand technique. Fluoroscopy time, procedure time, and number of CBCT-scans were recorded. All data are presented as median (ranges).

RESULTS

For biopsies using the freehand technique, more fluoroscopy time was necessary to guide the needle onto the target, 165 s (83-333 s) compared to 87 s (44-190 s) for laser guidance (p < 0.001). Procedure times were shorter for freehand-guided biopsies, 24 min versus 30 min for laser guidance (p < 0.001).

CONCLUSION

The use of laser guidance during CBCT-guided biopsies significantly reduces fluoroscopy time.

Radiation dose and quickness of needle CT-interventions using a laser navigation system (LNS) compared with conventional method

PURPOSE

The aim of this study was to analyse the radiation dose and quickness of needle interventions using a Laser Navigation System (LNS-group) compared with conventional method (control-group).

MATERIALS AND METHODS

In this prospective, randomized, comparative study 58 patients (19 females, 39 males; mean age, 62.9 years) were punctured either with LNS (n=29) or with conventional method with a skin mark of the puncture site (n=29). In the LNS method the puncture site was marked with laser without additional CT. Thoracic and abdominal intervention was performed in 30 and 28 patients, respectively. Radiation dose and time of the procedures were analysed. Statistical significance was calculated according to the Mann-Whitney-U-test.

RESULTS

Mean target access path in the patients of the LNS group was 6.0 cm (range, 3.0-10.1cm) and in the control group 6.0 cm (range, 1.0-10.3 cm). Time duration of complete intervention in the LNS group was 20:25 min (range, 07:00-34:00 min) and in the control group 28:00 min (range, 13:00-51:00 min). The dose-length-product (DLP) of intervention scan of the LNS group was 42.3 mGy cm (range, 10-125 mGy cm), and of the control group 59.7 mGy cm (range, 25-176.42 mGy cm).

CONCLUSION

Using the LNS for CT-guided interventions results in faster intervention time with a lower dose.

Comparison of CT Fluoroscopy-Guided Manual and CT-Guided Robotic Positioning System for In Vivo Needle Placements in Swine Liver

PURPOSE

To compare CT fluoroscopy-guided manual and CT-guided robotic positioning system (RPS)-assisted needle placement by experienced IR physicians to targets in swine liver.

MATERIALS AND METHODS

Manual and RPS-assisted needle placement was performed by six experienced IR physicians to four 5 mm fiducial seeds placed in swine liver (n = 6). Placement performance was assessed for placement accuracy, procedure time, number of confirmatory scans, needle manipulations, and procedure radiation dose. Intra-modality difference in performance for each physician was assessed using paired t test. Inter-physician performance variation for each modality was analyzed using Kruskal-Wallis test.

RESULTS

Paired comparison of manual and RPS-assisted placements to a target by the same physician indicated accuracy outcomes was not statistically different (manual: 4.53 mm; RPS: 4.66 mm; p = 0.41), but manual placement resulted in higher total radiation dose (manual: 1075.77 mGy/cm; RPS: 636.4 mGy/cm; p = 0.03), required more confirmation scans (manual: 6.6; RPS: 1.6; p < 0.0001) and needle manipulations (manual: 4.6; RPS: 0.4; p < 0.0001). Procedure time for RPS was longer than manual placement (manual: 6.12 min; RPS: 9.7 min; p = 0.0003). Comparison of inter-physician performance during manual placement indicated significant differences in the time taken to complete placements (p = 0.008) and number of repositions (p = 0.04) but not in other study measures (p > 0.05). Comparison of inter-physician performance during RPS-assisted placement suggested statistically significant differences in procedure time (p = 0.02) and not in other study measures (p > 0.05).

CONCLUSIONS

CT-guided RPS-assisted needle placement reduced radiation dose, number of confirmatory scans, and needle manipulations when compared to manual needle placement by experienced IR physicians, with equivalent accuracy.

Image-guided microwave thermoablation of hepatic tumours using novel robotic guidance: an early experience

OBJECTIVE

To evaluate and compare novel robotic guidance and manual approaches based on procedural accuracy, procedural time, procedural performance, image quality as well as patient dose during image-guided microwave thermoablation.

METHOD

The study was prospectively performed between June 2013 and December 2013 using 70 patients. Forty randomly selected patients (group 1) were treated with manual guidance and 30 patients (group 2) were treated using a novel robotic guidance. Parameters evaluated were procedural accuracy, total procedural time, procedural performance, quantitative/qualitative image quality and patient dose. Two-sided Student's t test and Wilcoxon rank-sum test were used to test the significance of the data and p values less than 0.05 were considered statistically significant.

RESULT

Accuracy parameters were significantly higher in group 2 (all p < 0.05). Total procedural time showed a mean time difference of 3 min (group 2 > group 1; p = 0.0008). Volume CT dose index and dose-length product were significantly lower for group 2 compared to group 1 (all p < 0.05) for CT fluoroscopy imaging. Total procedural performance score was higher for group 2 compared to group 1 (p = 0.0001). Image quality parameters were insignificant between examined groups.

CONCLUSION

The novel robotic guided approach improved the accuracy of targeting the target tumour, reduced patient dose and increased procedural performance (which influences the procedural safety) during ablation.

KEY POINTS

• Few reports are available in the literature regarding robotic-assisted liver microwave ablation. • The robotic guided approach improved accuracy of localizing the target tumour. • Radiation dose on patients was reduced with the robotic guidance. • Numbers of insertions and readjustments were reduced, lowering chances of complications.

Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions

OBJECTIVE

To report our experience using C-arm cone beam CT (C-arm CBCT) combined with the new remote operated positioning and guidance system, iSYS1, for needle guidance during spinal interventions.

METHODS

A C-arm CBCT with a flat panel angiography system was acquired (Artis Zeego; Siemens Healthcare Sector, Forchheim, Germany). Reconstruction of CT-like images and planning of the needle path were performed using a common workstation. The needle holder of iSYS1 acted as a guide during insertion of Kirschner (K) wires. 20 percutaneous K wires were placed in the pedicles at T2-T3, T7-T12, and L1-L2 in a cadaver specimen. Postprocedure C-arm CBCT scans were obtained to confirm the accuracy of the K wire placement.

RESULTS

All K wire placements were successfully performed. Mean planning time with Syngo iGuide was 4:16 min, mean positioning time of iSYS1 was 3:35 min, and mean placement time of the K wires was 2:22 min. Mean total intervention time was 10:13 min per pedicle. A mean deviation of 0.35 mm between the planned path and the placed K wire with a mean path length of 6.73 cm was documented.

CONCLUSIONS

Our results demonstrate the potential of combining C-arm CBCT with iSYS1 for safe and accurate percutaneous placement of pedicle K wires in spinal interventions.

Accuracy and efficacy of percutaneous biopsy and ablation using robotic assistance under computed tomography guidance: a phantom study

OBJECTIVE

To compare the accuracy of a robotic interventional radiologist (IR) assistance platform with a standard freehand technique for computed-tomography (CT)-guided biopsy and simulated radiofrequency ablation (RFA).

METHODS

The accuracy of freehand single-pass needle insertions into abdominal phantoms was compared with insertions facilitated with the use of a robotic assistance platform (n = 20 each). Post-procedural CTs were analysed for needle placement error. Percutaneous RFA was simulated by sequentially placing five 17-gauge needle introducers into 5-cm diameter masses (n = 5) embedded within an abdominal phantom. Simulated ablations were planned based on pre-procedural CT, before multi-probe placement was executed freehand. Multi-probe placement was then performed on the same 5-cm mass using the ablation planning software and robotic assistance. Post-procedural CTs were analysed to determine the percentage of untreated residual target.

RESULTS

Mean needle tip-to-target errors were reduced with use of the IR assistance platform (both P < 0.0001). Reduced percentage residual tumour was observed with treatment planning (P = 0.02).

CONCLUSION

Improved needle accuracy and optimised probe geometry are observed during simulated CT-guided biopsy and percutaneous ablation with use of a robotic IR assistance platform. This technology may be useful for clinical CT-guided biopsy and RFA, when accuracy may have an impact on outcome.

KEY POINTS

• A recently developed robotic intervention radiology assistance platform facilitates CT-guided interventions. • Improved accuracy of complex needle insertions is achievable. • IR assistance platform use can improve target ablation coverage.

A compliant parallel mechanism for needle intervention

This paper presents a compliant mechanism for fine motion of a medical robot for needle intervention procedure. The concept of this mechanism is created with the purpose of correcting a needle axis by translating a main robot for needle driving when an unexpected slip happens in needle insertion. In order to specify the concept, a planar compliant mechanism is designed so that the mechanism has maximized workspace for some given design condition. A simplified mathematical model for the designed mechanism is derived and then a pose controller is designed to track a desired trajectory in a plane, which is a similar situation that the compliant mechanism translates a needle driving robot to correct the direction of a needle. The simulation result shows good tracking performance.