A magnetic resonance conditional robot for lumbar spinal injection: Development and preliminary validation.

PURPOSE: This work presents the design and preliminary validation of a Magnetic Resonance (MR) conditional robot for lumbar injection for the treatment of lower back pain. METHODS: This is a 4-degree-of-freedom (DOF) robot that is 200 × 230 × 130 mm3 in volume and has a mass of 0.8 kg. Its lightweight and compact features allow it to be directly affixed to patient's back, establishing a rigid connection, thus reducing positional errors caused by patient movements during treatment. RESULTS: To validate the positioning accuracy of the needle by the robot, an electromagnetic (EM) tracking system and a needle with an EM sensor embedded in the tip were used for the free space evaluation with position accuracy of 0.88 ± 0.46 mm and phantom mock insertions using the Loop-X CBCT scanner with target position accuracy of 3.62 ± 0.92 mm. CONCLUSION: Preliminary experiments demonstrated that the proposed robot showed improvements and benefits in its rotation range, flexible needle adjustment, and sensor protection compared with previous and existing systems, offering broader clinical applications.

Optimal Concentric Tube Robot Design for Safe Intracerebral Hemorrhage Removal.

Purpose: The purpose of this paper is to investigate the geometrical design and path planning of Concentric tube robots (CTR) for intracerebral hemorrhage (ICH) evacuation, with a focus on minimizing the risk of damaging white matter tracts and cerebral arteries. Methods: To achieve our objective, we propose a parametrization method describing a general class of CTR geometric designs. We present mathematical models that describe the CTR design constraints and provide the calculation of a path risk value. We then use a genetic algorithm to determine the optimal tube geometry for targeting within the brain. Results: Our results show that a multi-tube CTR design can significantly reduce the risk of damaging critical brain structures compared to the conventional straight tube design. However, there is no significant relationship between the path risk value and the number and shape of the additional inner curved tubes. Conclusion: Considering the challenges of CTR hardware design, fabrication, and control, we conclude that the most practical geometry for a CTR path in ICH treatment is a straight outer tube followed by a planar curved inner tube. These findings have important implications for the development of safe and effective CTRs for ICH evacuation by enabling dexterous manipulation to minimize damage to critical brain structures.

PedBotLab: A Novel Video Game-Based Robotic Ankle Platform Created for Therapeutic Exercise for Children With Neurological Impairments.

AIMS: Assess the potential benefits of using PedBotLab, a clinic based robotic ankle platform with integrated video game software, to improve ankle active and passive range of motion, strength, selective motor control, gait efficiency, and balance. METHODS: Ten participants with static neurological injuries and independent ambulation participated in a 10-week pilot study (Pro00013680) to assess feasibility and efficacy of PedBotLab as a therapeutic device twice weekly. Isometric ankle strength, passive and active ankle range of motion, plantarflexor spasticity, selective motor control of the lower extremity, balance, and gait speed were measured pre- and post-trial. RESULTS: Statistically significant improvements were seen in flexibility, active range of motion, and strength in multiple planes of ankle motion. Ankle dorsiflexion with knee flexion and knee extension demonstrated statistically significant results in all outcome measures. No significant changes were observed in gait speed outcomes. CONCLUSIONS: The use of PedbotLab can lead to improvements in ankle strength, flexibility, and active range of motion for children with static neurological injuries. Future studies aim to evaluate the effect on gait quality and work toward developing a home-based device.

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

OBJECTIVE: Use of medical devices in the magnetic resonance environment is regulated by standards that include the ASTM-F2213 magnetically induced torque. This standard prescribes five tests. However, none can be directly applied to measure very low torques of slender lightweight devices such as needles. METHODS: We present a variant of an ASTM torsional spring method that makes a "spring" of 2 strings that suspend the needle by its ends. The magnetically induced torque on the needle causes it to rotate. The strings tilt and lift the needle. At equilibrium, the magnetically induced potential energy is balanced by the gravitational potential energy of the lift. Static equilibrium allows calculating the torque from the needle rotation angle, which is measured. Moreover, a maximum rotation angle corresponds to the maximum acceptable magnetically induced torque, under the most conservative ASTM acceptability criterion. A simple apparatus using the 2-string method is shown, it can be 3D printed, and the design files are shared. RESULTS: The analytical methods were tested against a numeric dynamic model, showing perfect concordance. The method was then tested experimentally in 1.5T and 3T MRI with commercial biopsy needles. Numeric test errors were immeasurably small. Torques between 0.0001 Nm and 0.0018 Nm were measured in MRI with 7.7% maximum difference between tests. The cost to make the apparatus is 58USD and design files are shared. CONCLUSION: The apparatus is simple and inexpensive and provides good accuracy as well. SIGNIFICANCE: The 2-string method provides a solution to measure very low torques in the MRI.

Development and assessment of novel assist device for cardiac cannulation.

PURPOSE: Congenital heart defects are the most common birth defects in the USA and in 25% of cases need to be treated with cardiovascular interventions. One of such interventions is the postoperative use of an extracorporeal membrane oxygenation (ECMO) machine for the treatment of cardiorespiratory failure. The process of placing the patient on the ECMO is extremely time-critical and requires the use of cardiac cannulation. For the first time, our team developed and evaluated a new quick-connect cannulation system that allows for rapid, easy, and safe ECMO cannulation in the pediatric population. The design should eliminate the need for purse-string sutures that are currently used to secure cannulas, as the cannulas will be inserted through a port that is glued to the cardiovascular tissue. METHODS: The rapid cannulation assistance device was designed on the SolidWorks computer-aided design software using the dimensions of the commercially available arterial and venous catheters. These designs were then 3D printed, and tensile testing was performed. Then, a flow loop was developed, and cannulation was performed and analyzed on both 3D-printed hearts and porcine hearts. RESULTS: The rapid cannulation assistance device was designed and 3D printed. Tensile testing found that the parts were strong enough to withstand forces that may be introduced in studies. 3D-printed and porcine heart tests with a flow loop found no leakage with the 3D-printed hearts but minimal leaking with the porcine hearts. However, this leakage was observed at the junction between the device and the heart, leading us to believe that a glue better suited to attach the device to the heart would prevent leakage in the future. CONCLUSIONS: This project successfully demonstrated how a rapid cannulation assistance device could be developed and tested. Future studies will be conducted that address device adhesion to the cardiovascular tissue so that accurate pressure and flow rates can be measured. Future studies will also include testing the device in a fluid environment to more effectively analyze the device success and comparing the time required to cannulate using our device compared to the standard of care.

A novel pneumatic drill for bone biopsy under MRI imaging.

PURPOSE: Bone biopsies are currently conducted under computed tomography (CT) guidance using a battery-powered drill to obtain tissue samples for diagnosis of suspicious bone lesions. However, this procedure is suboptimal as images produced under CT lack soft tissue discrimination and involve ionizing radiation. Therefore, our team developed an MRI-safe pneumatic drill to translate this clinical workflow into the MR environment, which can improve target visualization and eliminate radiation exposure. We compare drill times and quality of samples between the 2 drills using animal bones. METHODS: Five porcine spare rib bones were obtained from a butcher shop. Each bone was drilled twice using the Arrow OnControl battery-powered drill and twice using our pneumatically actuated drill. For this study, we used an 11-gauge bone biopsy needle set with an internal core capturing thread. A stopwatch recorded the overall time of drilling for each specimen obtained. RESULTS: All 20 samples collected contained a high-quality inner core and cortex. The total average time for drilling with the pneumatic drill was 8.5 s (+ / - 2.5 s) and 7.1 s (+ / - 1.4 s) with the standard battery-powered drill. CONCLUSION: Both drills worked well and were able to obtain comparable specimens. The pneumatic drill took slightly longer, 1.39 s on average, but this extra time would not be significant in clinical practice. We plan to use the pneumatic drill to enable MRI-safe bone biopsy for musculoskeletal lesions. Biopsy under MRI would provide excellent lesion visualization with no ionizing radiation.

Open Source MR-Safe Pneumatic Radial Inflow Motor and Encoder (PRIME): Design and Manufacturing Guidelines.

Actuators and encoders used in MR-guided robotic interventions are subject to strict requirements to ensure patient safety and MR imaging quality. In this paper, we present an open source computer aided design (CAD) of our MR-safe Pneumatic Radial Inflow Motor and Encoder (PRIME). PRIME is a parametrically designed motor that enables scalability based on torque and speed requirements for a wide range of MR-guided robotic procedures. The design consists of five primary modifiable parameters that define the entire motor geometry. All components of the motor are either 3D printed or available off-the-shelf. Quadrature encoding is achieved using a 3D printed housing and four fiber optic cables. Benchtop experiments were performed to validate the performance of the proposed design. To the best of our knowledge, this is the first open source MR-safe pneumatic motor and encoder in the field. We aim to share the design and manufacturing guidelines to lower the entry barriers for researchers interested in MR-guided robotics.

Evaluation of a novel MRI-safe needle guidance toolkit for streamlined arthrography procedures.

Currently, Magnetic Resonance arthrography procedures require two rooms and two imaging modalities: fluoroscopically guided needle insertion in a fluoroscopy suite, followed by diagnostic MRI in a separate MRI suite. The use of fluoroscopy for needle placement exposes patients to ionizing radiation, which is an important concern, especially in pediatrics. The need for two different rooms and coordinating times for these rooms complicates hospital resource scheduling and logistics. In addition, the added delays could expose younger children to additional risks associated with the use of general anesthesia. To address these issues, we propose a new technique to streamline the arthrography procedure. Our proposed technology aims to eliminate exposure to ionizing radiation and to streamline arthrography procedures that are conducted solely under MRI. This toolkit consists of a 3D slicer-based user interface, a spatially unique silicone grid template, and a hand-held needle guidance device. Together, these tools are intended to simplify and shorten the procedure while maintaining accuracy and precision comparable to the current gold standard procedure. In our cadaver study, we evaluated the feasibility and accuracy of our novel MRI-safe Needle Guidance Toolkit for MRI arthrography procedures, achieving an average targeting accuracy of 3.2 ± 1.0 mm. The results presented in this study showed the feasibility and promise of our novel MRI-safe needle guidance toolkit for arthrography procedures.

Flexible Needle Bending Model for Spinal Injection Procedures.

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

A systematic review of annotation for surgical process model analysis in minimally invasive surgery based on video.

BACKGROUND: Annotated data are foundational to applications of supervised machine learning. However, there seems to be a lack of common language used in the field of surgical data science. The aim of this study is to review the process of annotation and semantics used in the creation of SPM for minimally invasive surgery videos. METHODS: For this systematic review, we reviewed articles indexed in the MEDLINE database from January 2000 until March 2022. We selected articles using surgical video annotations to describe a surgical process model in the field of minimally invasive surgery. We excluded studies focusing on instrument detection or recognition of anatomical areas only. The risk of bias was evaluated with the Newcastle Ottawa Quality assessment tool. Data from the studies were visually presented in table using the SPIDER tool. RESULTS: Of the 2806 articles identified, 34 were selected for review. Twenty-two were in the field of digestive surgery, six in ophthalmologic surgery only, one in neurosurgery, three in gynecologic surgery, and two in mixed fields. Thirty-one studies (88.2%) were dedicated to phase, step, or action recognition and mainly relied on a very simple formalization (29, 85.2%). Clinical information in the datasets was lacking for studies using available public datasets. The process of annotation for surgical process model was lacking and poorly described, and description of the surgical procedures was highly variable between studies. CONCLUSION: Surgical video annotation lacks a rigorous and reproducible framework. This leads to difficulties in sharing videos between institutions and hospitals because of the different languages used. There is a need to develop and use common ontology to improve libraries of annotated surgical videos.

A methodology for the annotation of surgical videos for supervised machine learning applications.

PURPOSE: Surgical data science is an emerging field focused on quantitative analysis of pre-, intra-, and postoperative patient data (Maier-Hein et al. in Med Image Anal 76: 102306, 2022). Data science approaches can decompose complex procedures, train surgical novices, assess outcomes of actions, and create predictive models of surgical outcomes (Marcus et al. in Pituitary 24: 839-853, 2021; Røadsch et al. in Nat Mach Intell, 2022). Surgical videos contain powerful signals of events that may impact patient outcomes. A necessary step before the deployment of supervised machine learning methods is the development of labels for objects and anatomy. We describe a complete method for annotating videos of transsphenoidal surgery. METHODS: Endoscopic video recordings of transsphenoidal pituitary tumor removal surgeries were collected from a multicenter research collaborative. These videos were anonymized and stored in a cloud-based platform. Videos were uploaded to an online annotation platform. Annotation framework was developed based on a literature review and surgical observations to ensure proper understanding of the tools, anatomy, and steps present. A user guide was developed to trained annotators to ensure standardization. RESULTS: A fully annotated video of a transsphenoidal pituitary tumor removal surgery was produced. This annotated video included over 129,826 frames. To prevent any missing annotations, all frames were later reviewed by highly experienced annotators and a surgeon reviewer. Iterations to annotated videos allowed for the creation of an annotated video complete with labeled surgical tools, anatomy, and phases. In addition, a user guide was developed for the training of novice annotators, which provides information about the annotation software to ensure the production of standardized annotations. CONCLUSIONS: A standardized and reproducible workflow for managing surgical video data is a necessary prerequisite to surgical data science applications. We developed a standard methodology for annotating surgical videos that may facilitate the quantitative analysis of videos using machine learning applications. Future work will demonstrate the clinical relevance and impact of this workflow by developing process modeling and outcome predictors.

Non-Metallic MR-Guided Concentric Tube Robot for Intracerebral Hemorrhage Evacuation.

OBJECTIVE: We aim to develop and evaluate an MR-conditional concentric tube robot for intracerebral hemorrhage (ICH) evacuation. METHODS: We fabricated the concentric tube robot hardware with plastic tubes and customized pneumatic motors. The robot kinematic model was developed using a discretized piece-wise constant curvature (D-PCC) approach to account for variable curvature along the tube shape, and tube mechanics model was used to compensate torsional deflection of the inner tube. The MR-safe pneumatic motors were controlled using a variable gain PID algorithm. The robot hardware was validated in a series of bench-top and MRI experiments, and the robot's evacuation efficacy was tested in MR-guided phantom trials. RESULTS: The pneumatic motor was able to achieve a rotational accuracy of 0.32°±0.30° with the proposed variable gain PID control algorithm. The kinematic model provided a positional accuracy of the tube tip of 1.39 ± 0.54 mm. The robot was able to evacuate an initial 38.36 mL clot, leaving a residual hematoma of 8.14 mL after 5 minutes, well below the 15 mL guideline suggesting good post-ICH evacuation clinical outcomes. CONCLUSION: This robotic platform provides an effective method for MR-guided ICH evacuation. SIGNIFICANCE: ICH evacuation is feasible under MRI guidance using a plastic concentric tube, indicating potential feasibility in future live animal studies.

In situ guidance for MRI interventions using projected feedback.

PURPOSE: To develop and evaluate an augmented reality instrument guidance system for MRI-guided needle placement procedures such as musculoskeletal biopsy and arthrography. Our system guides the physician to insert a needle toward a target while looking at the insertion site without requiring special headgear. METHODS: The system is comprised of a pair of stereo cameras, a projector, and a computational unit with a touch screen. All components are designed to be used within the MRI suite (Zone 4). Multi-modality fiducial markers called VisiMARKERs, detectable in both MRI and camera images, facilitate automatic registration after the initial scan. The navigation feedback is projected directly onto the intervention site allowing the interventionalist to keep their focus on the insertion site instead of a secondary monitor which is often not in front of them. RESULTS: We evaluated the feasibility and accuracy of this system on custom-built shoulder phantoms. Two radiologists used the system to select targets and entry points on initial MRIs of these phantoms over three sessions. They performed 80 needle insertions following the projected guidance. The system targeting error was 1.09 mm, and the overall error was 2.29 mm. CONCLUSION: We demonstrated both feasibility and accuracy of this MRI navigation system. The system operated without any problems inside the MRI suite close to the MRI bore. The two radiologists were able to easily follow the guidance and place the needle close to the target without any intermediate imaging.

Modeling of Ultrasound Stimulation of Adolescent Pancreas for Insulin Release Therapy.

OBJECTIVES: Our previous published studies have focused on safety and effectiveness of using therapeutic ultrasound (TUS) for treatment of type 2 diabetes mellitus (T2DM) in preclinical models. Here we present a set of simulation studies to explore potential ultrasound application schemes that would be feasible in a clinical setting. METHODS: Using the multiphysics modeling tool OnScale, we created two-dimensional (2D) models of the human abdomen from CT images captured from one normal weight adolescent patient, and one obese adolescent patient. Based on our previous studies, the frequency of our TUS was 1 MHz delivered from a planar unfocused transducer. We tested five different insonation angles, as well as four ultrasound intensities combined with four different duty factors and five durations of application to explore how these variables effect the peak pressure and temperature delivered to the pancreas as well as surrounding tissue in the model. RESULTS: We determined that ultrasound applied directly from the anterior of the patient abdomen at 5 W/cm2 delivered consistent acoustic pressures to the pancreas at the levels which we have previously found to be effective at inducing an insulin release from preclinical models. CONCLUSIONS: Our modeling work indicates that it may be feasible to non-invasively apply TUS in clinical treatment of T2DM.

EasyTBSA as a method for calculating total body surface area burned: a validation study.

BACKGROUND: Current methods of burn estimation can lead to incorrect estimates of the total body surface area (TBSA) burned, especially among injured children. Inaccurate estimation of burn size can impact initial management, including unnecessary transfer to burn centres and fluid overload during resuscitation. To address these challenges, we developed a smartphone application (EasyTBSA) that calculates the TBSA of a burn using a body-part by body-part approach. The aims of this study were to assess the accuracy of the EasyTBSA application and compare its performance to three established methods of burn size estimation (Lund-Browder Chart, Rule of Nines and Rule of Palms). METHODS: Twenty-four healthcare providers used each method to estimate burn sizes on moulaged manikins. The manikins represented different ages (infant, child and adult) with different TBSA burns (small <20%, medium 20%-49% and large >49%). We calculated the accuracy of each method as the difference between the user-estimated and actual TBSA. The true value of the complete body surface area of the manikins was obtained by three-dimensional scans. We used multivariable modelling to control for manikin size and method. RESULTS: Among all age groups and burn sizes, the EasyTBSA application had the greatest accuracy for burn size estimation (-0.01%, SD 3.59%) followed by the Rule of Palms (3.92%, SD 10.71%), the Lund-Browder Chart (4.42%, SD 5.52%) and the Rule of Nines (5.05%, SD 6.87%). CONCLUSIONS: The EasyTBSA application may improve the estimation of TBSA compared with existing methods.

The past, present, and future of child growth monitoring: A review and primer for clinical genetics.

Child growth measurements are critical vital signs to track, with every individual child growth curve potentially revealing a story about a child's health and well-being. Simply put, every baby born requires basic building blocks to grow and thrive: proper nutrition, love and care, and medical health. To ensure that every child who is missing one of these vital aspects is identified, growth is traditionally measured at birth and each well-child visit. While the blue and pink growth curves appear omnipresent in pediatric clinics, it is surprising to realize that their use only became standard of care in 1977 when the National Center for Health Statistics (NCHS) adopted the growth curve as a clinical tool for health. Behind this practice lies a socioeconomically, culturally, and politically complex interplay of individuals and institutions around the world. In this review, we highlight the often forgotten past, current state of practice, and future potential of this powerful clinical tool: the growth reference chart, with a particular focus on clinical genetics practice. The goal of this article is to understand ongoing work in the field of anthropometry (the scientific study of human measurements) and its direct impact on modern pediatric and genetic patient care.

Toward Robust Partial-Image Based Template Matching Techniques for MRI-Guided Interventions.

We have developed an MRI-safe needle guidance toolkit for MRI-guided interventions intended to enable accurate positioning for needle-based procedures. The toolkit allows intuitive and accurate needle angulation and entry point positioning according to an MRI-based plan, using a flexible, patterned silicone 2D grid. The toolkit automatically matches the grid on MRI planning images with a physical silicon grid placed conformally on the patient's skin and provides the Interventional Radiologist an easy-to-use guide showing the needle entry point on the silicon grid as well as needle angle information. The radiologist can use this guide along with a 2-degree-of-freedom (rotation and angulation relative to the entry point) hand-held needle guide to place the needle into the anatomy of interest. The initial application that we are considering for this toolkit is arthrography, a diagnostic procedure to evaluate the joint space condition. However, this toolkit could be used for any needle-based and percutaneous procedures such as MRI-guided biopsy and facet joint injection. For matching the images, we adopt a transformation parameter estimation technique using the phase-only correlation method in the frequency domain. We investigated the robustness of this method against rotation, displacement, and Rician noise. The algorithm was able to successfully match all the dataset images. We also investigated the accuracy of identifying the entry point from registered template images as a prerequisite for a future targeting study. Application of the template matching algorithm to locate the needle entry points within the MRI dataset resulted in an average entry point location estimation accuracy of 0.12 ±0.2 mm. This promising result motivates a more detailed assessment of this algorithm in the future including a targeting study on a silicon phantom with embedded plastic targets to investigate the end-to-end accuracy of this automatic template matching algorithm in the interventional MRI room.

An MR-Conditional Needle Driver for Robot-Assisted Spinal Injections: Design Modifications and Evaluations.

This paper introduces design modifications to our MR-Conditional, 2-degree-of-freedom (DOF), remotely-actuated needle driver for MRI-guided spinal injections. The new needle driver should better meet cleaning and sterilization guidelines needed for regulatory approval, preserve the sterile field during intraoperative needle attachment, and offer better ergonomics and intuitiveness when handling the device. Dy-namic and static force and torque required to properly install the needle driver onto our 4-DOF robot base are analyzed, which provide insight into the risks of intraoperative tool attachment in the setting of robot-assisted spinal injections under MRI guidance.

Validation of a novel path planner for stereotactic neurosurgical interventions-A retrospective clinical study.

BACKGROUND: The gold standard workflow for targeting structures in the brain involves manual path planning. This preoperative manual path planning is very time-intensive and laborious, especially when some outcome measures such as maximum ablation and penetration depth has to be optimised. METHODS: Our novel path planner generates an optimal path which maximises the hippocampus penetration and distance from critical structures using a precomputed cost map and a reward map. RESULTS: The average penetration ratio for 12 cases is 88.13 ± 23.23% for a resolution of 1° and a safety margin of 1 mm. Average run time for the path planner based on 1° resolution was 1.99 ± 0.68 min. CONCLUSIONS: Results show that the algorithm can generate safe and clinically relevant paths with a quantitative representation of the penetration depth and is faster than the average reported time for manual path planning.

Quantification of manipulation forces needed for robot-assisted reduction of the ankle syndesmosis: an initial cadaveric study.

PURPOSE: Manual surgical manipulation of the tibia and fibula is necessary to properly align and reduce the space in ankle fractures involving sprain of the distal tibiofibular syndesmosis. However, manual reduction is highly variable and can result in malreduction in about half of the cases. Therefore, we are developing an image-guided robotic assistant to improve reduction accuracy. The purpose of this study is to quantify the forces associated with reduction of the ankle syndesmosis to define the requirements for our robot design. METHODS: Using a cadaveric specimen, we designed a fixture jig to fix the tibia securely on the operating table. We also designed a custom fibula grasping plate to which a force-torque measuring device is attached. The surgeon manually reduced the fibula utilizing this construct while translational and rotational forces along with displacement were being measured. This was first performed on an intact ankle without ligament injury and after the syndesmosis ligaments were cut. RESULTS: Six manipulation techniques were performed on the three principal directions of reduction at the cadaveric ankle. The results demonstrated the maximum force applied to the lateral direction to be 96.0 N with maximum displacement of 8.5 mm, applied to the anterior-posterior direction to be 71.6 N with maximum displacement of 10.7 mm, and the maximum torque applied to external-internal rotation to be 2.5 Nm with maximum rotation of 24.6°. CONCLUSIONS: The specific forces needed to perform the distal tibiofibular syndesmosis manipulation are not well understood. This study quantified these manipulation forces needed along with their displacement for accurate reduction of ankle syndesmosis. This is a necessary first step to help us define the design requirements of our robotic assistance from the aspects of forces and displacements.