Mixed reality navigation system for ultrasound-guided percutaneous punctures: a pre-clinical evaluation

Multipole Magnetic Needle Positioning Method for Ultrasound-Guided Puncture

OBJECTIVE

Ultrasound-guided puncture often faces challenges in visualizing the needle. Needle positioning systems can provide real-time needle position information to the doctor. Due to its large spatial footprint and limited portability, positioning methods based on external tracking systems have not been widely adopted. In this study, we developed a multipole magnetic needle positioning method for ultrasound-guided puncture, aiming to maintain the portability advantages of ultrasound while achieving good positioning accuracy.

METHODS

A magnetic sensor array is installed within the ultrasound probe. The needle continuously generates a specific magnetic field through multipole magnetization. A positioning algorithm combining magnetic gradient tensor method and direct inversion method can accurately locate the position of the needle. To improve localization accuracy, an environmental magnetic field identification method based on machine learning is employed.

RESULTS

The environmental magnetic field identification method achieved an accuracy, precision, recall, and F1 score of 98.38%, 98.70%, 98.06%, and 98.38%, respectively. During the puncture process, the maximum positioning errors of tip and direction are respectively 3.49 mm and 4.93. In the phantom puncture experiment, novices who use our positioning system have a higher first-time success rate.

CONCLUSION

This needle positioning method can accurately locate the multipole magnetic needle. The ultrasound-guided puncture system using this method can display the position of the puncture needle in real time. It can help novices complete puncture tasks more easily.

SIGNIFICANCE

This system provides a new approach to the design of ultrasound-guided puncture navigation systems. The positioning algorithm can also be applied to locate other elongated ferromagnetic objects.

Metaverse-based simulation: a scoping review of charting medical education over the last two decades in the lens of the 'marvelous medical education machine'

BACKGROUND

Over the past two decades, the use of Metaverse-enhanced simulations in medical education has witnessed significant advancement. These simulations offer immersive environments and technologies, such as augmented reality, virtual reality, and artificial intelligence that have the potential to revolutionize medical training by providing realistic, hands-on experiences in diagnosing and treating patients, practicing surgical procedures, and enhancing clinical decision-making skills. This scoping review aimed to examine the evolution of simulation technology and the emergence of metaverse applications in medical professionals' training, guided by Friedman's three dimensions in medical education: physical space, time, and content, along with an additional dimension of assessment.

METHODS

In this scoping review, we examined the related literature in six major databases including PubMed, EMBASE, CINAHL, Scopus, Web of Science, and ERIC. A total of 173 publications were selected for the final review and analysis. We thematically analyzed these studies by combining Friedman's three-dimensional framework with assessment.

RESULTS

Our scoping review showed that Metaverse technologies, such as virtual reality simulation and online learning modules have enabled medical education to extend beyond physical classrooms and clinical sites by facilitating remote training. In terms of the Time dimension, simulation technologies have made partial but meaningful progress in supplementing traditional time-dependent curricula, helping to shorten learning curves, and improve knowledge retention. As for the Content dimension, high-quality simulation and metaverse content require alignment with learning objectives, interactivity, and deliberate practice that should be developmentally integrated from basic to advanced skills. With respect to the Assessment dimension, learning analytics and automated metrics from metaverse-enabled simulation systems have enhanced competency evaluation and formative feedback mechanisms. However, their integration into high-stakes testing is limited, and qualitative feedback and human observation remain crucial.

CONCLUSION

Our study provides an updated perspective on the achievements and limitations of using simulation to transform medical education, offering insights that can inform development priorities and research directions for human-centered, ethical metaverse applications that enhance healthcare professional training.

Evaluation of augmented reality training for a navigation device used for CT-guided needle placement

PURPOSE

Numerous navigation devices for percutaneous, CT-guided interventions exist and are, due to their advantages, increasingly integrated into the clinical workflow. However, effective training methods to ensure safe usage are still lacking. This study compares the potential of an augmented reality (AR) training application with conventional instructions for the Cube Navigation System (CNS), hypothesizing enhanced training with AR, leading to safer clinical usage.

METHODS

An AR-tablet app was developed to train users puncturing with CNS. In a study, 34 medical students were divided into two groups: One trained with the AR-app, while the other used conventional instructions. After training, each participant executed 6 punctures on a phantom (204 in total) following a standardized protocol to identify and measure two potential CNS procedural user errors: (1) missing the coordinates specified and (2) altering the needle trajectory during puncture. Training performance based on train time and occurrence of procedural errors, as well as scores of User Experience Questionnaire (UEQ) for both groups, was compared.

RESULTS

Training duration was similar between the groups. However, the AR-trained participants showed a 55.1% reduced frequency of the first procedural error (p > 0.05) and a 35.1% reduced extent of the second procedural error (p < 0.01) compared to the conventionally trained participants. UEQ scores favored the AR-training in five of six categories (p < 0.05).

CONCLUSION

The AR-app enhanced training performance and user experience over traditional methods. This suggests the potential of AR-training for navigation devices like the CNS, potentially increasing their safety, ultimately improving outcomes in percutaneous needle placements.

Miniaturized electromagnetic tracking enables efficient ultrasound-navigated needle insertions

Ultrasound (US) has gained popularity as a guidance modality for percutaneous needle insertions because it is widely available and non-ionizing. However, coordinating scanning and needle insertion still requires significant experience. Current assistance solutions utilize optical or electromagnetic tracking (EMT) technology directly integrated into the US device or probe. This results in specialized devices or introduces additional hardware, limiting the ergonomics of both the scanning and insertion process. We developed the first ultrasound (US) navigation solution designed to be used as a non-permanent accessory for existing US devices while maintaining the ergonomics during the scanning process. A miniaturized EMT source is reversibly attached to the US probe, temporarily creating a combined modality that provides real-time anatomical imaging and instrument tracking at the same time. Studies performed with 11 clinical operators show that the proposed navigation solution can guide needle insertions with a targeting accuracy of about 5 mm, which is comparable to existing approaches and unaffected by repeated attachment and detachment of the miniaturized tracking solution. The assistance proved particularly helpful for non-expert users and needle insertions performed outside of the US plane. The small size and reversible attachability of the proposed navigation solution promises streamlined integration into the clinical workflow and widespread access to US navigated punctures.

Feasibility and Safety of Percutaneous Puncture Guided by a 5G-Based Telerobotic Ultrasound System: An Experimental Study

PURPOSE

To evaluate the feasibility and safety of percutaneous puncture guided by a 5th generation mobile communication technology (5G)-based telerobotic ultrasound system in phantom and animal experiments.

MATERIALS AND METHODS

In the phantom experiment, 10 simulated lesions were punctured, once at each of two angles for each lesion, under the guidance of a telerobotic ultrasound system and ultrasound-guided freehand puncture. Student's t test was used to compare the two methods in terms of puncture accuracy, total operation duration, and puncture duration. In the animal experiment, under the guidance of the telerobotic ultrasound system, an 18G puncture needle was used to puncture 3 target steel beads in the liver, right kidney, and right gluteal muscle, respectively. The animal experiment had no freehand ultrasound-guided control group. After puncture, a CT scan was performed to verify the position of the puncture needle in relation to the target, and the complications and puncture duration, etc., were recorded.

RESULTS

In the phantom experiment, the mean accuracies of puncture under telerobotic ultrasound guidance and conventional ultrasound guidance were 1.8 ± 0.3 mm and 1.6 ± 0.3 mm (P = 0.09), respectively; therefore, there was no significant difference in the accuracy of the two guide methods. In the animal experiment, the first-attempt puncture success (the needle tip close to the target) rate was 93%. Polypnea occurred during one puncture. No other intraoperative or postoperative complications were observed.

CONCLUSION

Puncture guided by a 5G-based telerobotic ultrasound system has shown good feasibility and safety in phantom and animal experiments.

A robotic system for transthoracic puncture of pulmonary nodules based on gated respiratory compensation

BACKGROUND AND OBJECTIVE

With the urgent demands for rapid and precise localization of pulmonary nodules in procedures such as transthoracic puncture biopsy and thoracoscopic surgery, many surgical navigation and robotic systems are applied in the clinical practice of thoracic operation. However, current available positioning methods have certain limitations, including high radiation exposure, large errors from respiratory, complicated and time-consuming procedures, etc. METHODS: To address these issues, a preoperative computed tomography (CT) image-guided robotic system for transthoracic puncture was proposed in this study. Firstly, an algorithm for puncture path planning based on constraints from clinical knowledge was developed. This algorithm enables the calculation of Pareto optimal solutions for multiple clinical targets concerning puncture angle, puncture length, and distance from hazardous areas. Secondly, to eradicate intraoperative radiation exposure, a fast registration method based on preoperative CT and gated respiration compensation was proposed. The registration process could be completed by the direct selection of points on the skin near the sternum using a hand-held probe. Gating detection and joint optimization algorithms are then performed on the collected point cloud data to compensate for errors from respiratory motion. Thirdly, to enhance accuracy and intraoperative safety, the puncture guide was utilized as an end effector to restrict the movement of the optically tracked needle, then risky actions with patient contact would be strictly limited.

RESULTS

The proposed system was evaluated through phantom experiments on our custom-designed simulation test platform for patient respiratory motion to assess its accuracy and feasibility. The results demonstrated an average target point error (TPE) of 2.46 ± 0.68 mm and an angle error (AE) of 1.49 ± 0.45° for the robotic system.

CONCLUSIONS

In conclusion, our proposed system ensures accuracy, surgical efficiency, and safety while also reducing needle insertions and radiation exposure in transthoracic puncture procedures, thus offering substantial potential for clinical application.

Swallowable Intragastric Balloon: First Consecutive Experience in Argentina

Background: Swallowable balloons are innovative devices for the treatment of obesity. Endoscopy or anesthesia for implantation is not required. They are generally well tolerated and experience reports satisfactory results in relation to weight loss. The objective of this study was to analyze the first experience with the implementation of a swallowable balloon in Argentina. Methods: It is a descriptive retrospective observational study on the treatment of obesity in patients who underwent swallowable balloons in Argentina, admitted to one center, in a period time of 12 months with a follow-up of 6 months. Results: A total of n = 153 patients were recruited between June 2021 and May 2022, 78% were women and 22% men. The average age was 39 years. Average body mass index was 29.5 kg/m². Balloon implantation was performed with complete swallowing by the patients in 19.4% of the cases, swallowing with operator assistance in 55.5%, and swallowing with stylet assistance in 25%. The adverse effects reported were abdominal pain (80%), nausea (60%), vomiting (38%), headache (36%), gastroesophageal reflux (29%), constipation (11%), and diarrhea (7%). No deaths were reported. A mean 4-month weight loss of 12% was reported. Conclusion: Swallowable balloon for the treatment of obesity is effective, safe, and well tolerated. Adverse effects are not severe.

Evaluating Atherosclerosis of the Abdominal Aorta in Rabbits Using 2-D Strain Imaging

After establishment of an animal model of atherosclerosis, speckle tracking imaging was performed to analyze the correlation between ultrasound characteristics and pathological manifestations. Rabbits were divided into the normal control (NC) and atherosclerosis (AS) groups. Rabbits in the AS group were subjected to ultrasound-guided balloon injury of the abdominal aorta and fed a high-fat diet for 16 wk. Rabbits in the NC group were fed a normal diet for the same period. After 16 wk, all animals underwent serological tests, ultrasound and speckle tracking circumferential strain analysis. In the AS group, 28 hypo-echoic plaques had formed. The circumferential strain of six segments at the short axis of plaques in the AS group was lower than that in the NC group (p < 0.001), and global circumferential strain (GCS) in the AS group was significantly reduced compared with the NC group (p < 0.001). In the AS group, the area ratio of type I to type III collagen fibers was smaller than that in the NC group. The GCS of atherosclerotic plaques was positively correlated with the area ratio of type I to type III collagen fibers in plaques (r = 0.7181, p < 0.001). In conclusion, there is a significant positive correlation between the decreased circumferential strain and the decreased area ratio of type I to type III collagen fibers in hypo-echoic plaques.

Application of a three-dimensional visualization model in intraoperative guidance of percutaneous nephrolithotomy

OBJECTIVES

To establish a three-dimensional visualization model of percutaneous nephrolithotomy, apply it to guiding intraoperative puncture in a mixed reality environment, and evaluate its accuracy and clinical value.

METHODS

Patients with percutaneous nephrolithotomy indications were prospectively divided into three-dimensional group and control group with a ratio of 1:2. For patients in three-dimensional group, positioning markers were pasted on the skin and enhanced computed tomography scanning was performed in the prone position. Holographic three-dimensional models were made and puncture routes were planned before operation. During the operation, the three-dimensional model was displayed through HoloLens glass and visually registered with the patient's body. Puncture of the target renal calyx was performed under three-dimensional-image guiding and ultrasonic monitoring. Patients in the control group underwent routine percutaneous nephrolithotomy in the prone position under the monitoring of B-ultrasound. Deviation distance of the kidney, puncture time, puncture attempts, channel coincidence rate, stone clearance rate, and postoperative complications were assessed.

RESULTS

Twenty-one and 40 patients were enrolled in three-dimensional and control group, respectively. For three-dimensional group, the average deviation between virtual and real kidney was 3.1 ± 2.9 mm. All punctures were performed according to preoperative planning. Compared with the control group, the three-dimensional group had shorter puncture time (8.9 ± 3.3 vs 14.5 ± 6.1 min, P < 0.001), fewer puncture attempts (1.4 ± 0.6 vs 2.2 ± 1.5, P = 0.009), and might also have a better performance in stone clearance rate (90.5% vs 72.5%, P = 0.19) and postoperative complications (P = 0.074).

CONCLUSIONS

The percutaneous nephrolithotomy three-dimensional model manifested acceptable accuracy and good value for guiding puncture in a mixed reality environment.

Image-Guided Surgical Training in Percutaneous Hepatobiliary Procedures: Development of a Realistic and Meaningful Bile Duct Dilatation Porcine Model

Background: Malignant or benign biliary obstructions can be successfully managed with minimally invasive percutaneous interventions. Since percutaneous approaches are challenging, extensive training using relevant models is fundamental to improve the proficiency of percutaneous physicians. The aim of this experimental study was to develop an in vivo training model in pigs to simulate bile duct dilatation to be used during percutaneous biliary interventions. Materials and Methods: Twenty-eight large white pigs were involved and procedures were performed in an experimental hybrid operating room. Under general anesthesia, animals underwent a preoperative magnetic resonance cholangiography (MRC). Afterward, the common bile duct was isolated and ligated laparoscopically. A postoperative MRC was performed 72 hours after the procedure to evaluate bile duct dilatation. The In vivo models presenting an effective dilatation model were included in the hands-on part of a percutaneous surgery training course. Animals were euthanized at the end of the training session. Results: Postoperative MRC confirmed the presence of bile duct dilatation in the survival pigs (n = 25). No intraoperative complications occurred and mean operative time was 15.8 ± 5.27 minutes. During the course, 27 trainees could effectively perform percutaneous transhepatic cholangiography, bile duct drainage, biliary duct dilatation, and stent placement, with a > 90% success rate, thereby validating the experimental model. All animals survived during the training procedures and complications occurred in 28.3% of cases. Conclusion: The creation of an in vivo bile duct dilatation animal model is feasible with a low short-term mortality. It provides a realistic and meaningful training model in percutaneous biliary procedures.

Image-Guided Surgery for Common Bile Duct Stones After Roux-en-Y Gastric Bypass

Background: The relationship between obesity with common bile duct stone (CBDS) is close and increases after a Roux-en-Y gastric bypass (RYGB). Due to the anatomical modification, direct endoscopic access is not always possible. For this reason, image-guided surgery (IGS) by percutaneous transhepatic biliary drainage (PTBD) of the common bile duct (CBD) could be a first-line approach for the treatment of post-RYGB choledocholithiasis. The aim of this study was to analyze the feasibility and safety of CBDS treatment after RYGB with IGS. Materials and Methods: We present a descriptive retrospective observational multicentric study on the treatment of choledocholithiasis in patients operated on for RYGB using IGS through a minimally invasive approach by PTBD. The diagnosis of CBDS was made according to the symptoms of the patients, supported by blood tests, and medical images. Treatment was planned in two stages: in the first step, a PTBD was performed, and in the second step the choledocholithiasis was removed. Results: Of a total of 1403 post-RYGB patients, 21 presented choledocholithiasis. Of these, n = 18 were included. Symptoms were reported in n = 15 (8 cholestatic jaundice, 7 cholangitis), whereas n = 3 were asymptomatic. Percutaneous treatment was performed in all these patients, treated with a balloon and stone basket. A hyperamylasemia without pancreatitis was observed in 3 patients. No complications or deaths associated with the procedure were reported. The average hospital stay was 8.6 days. Conclusion: IGS is an interesting option for the treatment CBDS after RYGB. For these patients, PTBD is feasible and safe.

Application of a novel material in the inguinal region using a totally percutaneous approach in an animal model: a new potential technique?

PURPOSE

To evaluate the feasibility and safety of a new percutaneous image-guided surgery technique to simulate a hernia repair using hydrogel.

MATERIALS AND METHODS

A comparative prospective study was conducted in animals, with survival. Five pigs without any hernias were used. A hydrogel was injected at a site corresponding to the preperitoneal inguinal region. This procedure was performed bilaterally. An image-guided needle (ultrasound and computed tomography) was used, through which the material was injected. After survival, the local and systemic inflammatory reaction generated by the new material, was studied.

RESULTS

All animals survived the procedure. No hemorrhagic or infectious complications were reported. The solidification of the material occurred as expected. In eight out of ten cases, the material was found in the planned site. No systemic inflammatory reaction secondary to the administration of hydrogel was reported. The adhesion of the material to surrounding tissues was satisfactory.

CONCLUSION

The introduction of a liquid material which solidifies after injection in a short time (hydrogel) using a needle is feasible. The combined CT-scan and US image guidance allows for the percutaneous placement of the needle in the required location. The introduced hydrogel remains in this space, corresponding to the inguinal region, without moving. The placed hydrogel compresses the posterior wall composed of the transversalis fascia, supporting the potential use of hydrogel for hernia defects.

Feasibility of mixed reality-based intraoperative three-dimensional image-guided navigation for atlanto-axial pedicle screw placement

This study aimed to evaluate the safety and accuracy of mixed reality-based intraoperative three-dimensional navigated pedicle screws in three-dimensional printed model of fractured upper cervical spine. A total of 27 cervical model from patients of upper cervical spine fractures formed the study group. All the C1 and C2 pedicle screws were inserted under mixed reality-based intraoperative three-dimensional image-guided navigation system. The accuracy and safety of the pedicle screw placement were evaluated on the basis of postoperative computerized tomography scans. A total of 108 pedicle screws were properly inserted into the cervical three-dimensional models under mixed reality-based navigation, including 54 C1 pedicle screws and 54 C2 pedicle screws. Analysis of the dimensional parameters of each pedicle at C1/C2 level showed no statistically significant differences in the ideal and the actual entry points, inclined angles, and tailed angles. No screw was misplaced outside the pedicle of the three-dimensional printed model, and no ionizing X-ray radiation was used during screw placement under navigation. It is easy and safe to place C1/C2 pedicle screws under MR surgical navigation. Mixed reality-based navigation is feasible within upper cervical spinal fractures with improved safety and accuracy of C1/C2 pedicle screw insertion.