High Anatomical Fidelity Research Articles

Simulation-Based Medical Education: 3D Printing and the Seldinger Technique

Three-dimensional (3D)-printed models with high anatomic fidelity are an increasingly viable tool in simulation-based medical education. One advantage of 3D models is they provide enhanced tactile and spatial understanding of complex anatomy to develop technical skills used in minimally invasive procedures. We propose that 3D anatomical models can improve the development of interventional radiology vascular access skills—first described in the 1950s as the Seldinger technique—for pre-clerkship medical students. The early adoption of 3D-printed technology in pre-clinical medical education can lead to improved student engagement and satisfaction when learning procedural techniques. This study involved creating a 3D model of the upper limb vasculature from an anonymized Computed tomography (CT) angiogram, using it as a medical education tool for 31 pre-clinical medical students practicing the Seldinger Technique on a prefabricated venipuncture upper limb, and assessing student satisfaction with this form of learning. Overall, attendees responded positively to the incorporation of the 3D model in medical education to improve their anatomic understanding and application of the Seldinger technique. These results indicate that the use of 3D models in simulation-based medical education can provide benefits in acquiring technical skills and the potential to decrease training costs without harming a patient.

Fabrication of Soft Transparent Patient-Specific Vascular Models with Stereolithographic 3D printing and Thiol-Based Photopolymerizable Coatings.

An ideal vascular phantom should be anatomically accurate, have mechanical properties as close as possible to the tissue, and be sufficiently transparent for ease of visualization. However, materials that enable the convergence of these characteristics have remained elusive. The fabrication of patient-specific vascular phantoms with high anatomical fidelity, optical transparency, and mechanical properties close to those of vascular tissue is reported. These final properties are achieved by 3D printing patient-specific vascular models with commercial elastomeric acrylic-based resins before coating them with thiol-based photopolymerizable resins. Ternary thiol-ene-acrylate chemistry is found optimal. A PETMP/allyl glycerol ether (AGE)/polyethylene glycol diacrylate (PEGDA) coating with a 30/70% AGE/PEGDA ratio applied on a flexible resin yielded elastic modulus, UTS, and elongation of 3.41MPa, 1.76 MPa, and 63.2%, respectively, in range with the human aortic wall. The PETMP/AGE/PEGDA coating doubled the optical transmission from 40% to 80%, approaching 88% of the benchmark silicone-based elastomer. Higher transparency correlates with a decrease in surface roughness from 2000 to 90nm after coating. Coated 3D-printed anatomical replicas are showcased for pre-procedural planning and medical training with good radio-opacity and echogenicity. Thiol-click chemistry coatings, as a surface treatment for elastomeric stereolithographic 3D-printed objects, address inherent limitations of photopolymer-based additive manufacturing.

Replicating Skull Base Anatomy With 3D Technologies: A Comparative Study Using 3D-scanned and 3D-printed Models of the Temporal Bone.

3D technologies, including structured light scanning (SLS), microcomputed tomography (micro-CT), and 3D printing, are valuable tools for reconstructing temporal bone (TB) models with high anatomical fidelity and cost-efficiency. Operations involving TB require intimate knowledge of neuroanatomical structures-a demand that is currently met through dissection of limited cadaveric resources. We aimed to document the volumetric reconstruction of TB models using 3D technologies and quantitatively assess their anatomical fidelity. In the primary analysis, 14 anatomical characteristics of right-side TB from 10 dry skulls were measured. Each skull was 3D-scanned using SLS to generate virtual models, which were measured using mesh processing software. Metrics were analyzed using mean absolute differences and one-sample t tests with Bonferroni correction. In the secondary analysis, an individualized right-side TB specimen (TBi) was 3D-scanned using SLS and micro-CT, and 3D-printed on a stereolithography printer. Measurements of each virtual and 3D-printed model were compared to measurements of TBi. Significant differences between the physical skulls and virtual models were observed for 11 of 14 parameters (p < 0.0036), with the greatest mean difference in the length of petrous ridge (2.85 mm) and smallest difference in the diameter of stylomastoid foramen (0.67 mm). In the secondary analysis, greater mean differences were observed between TBi and virtual models than between TBi and 3D-printed models. For the first time, our study provides quantitative measurements of TB anatomy to demonstrate that 3D technologies can facilitate individualized and highly accurate reconstructions of TB, which may benefit anatomy education, clinical training, and preoperative planning.

A 3D Computational Head Model Under Dynamic Head Rotation and Head Extension Validated Using Live Human Brain Data, Including the Falx and the Tentorium.

We employ an advanced 3D computational model of the head with high anatomical fidelity, together with measured tissue properties, to assess the consequences of dynamic loading to the head in two distinct modes: head rotation and head extension. We use a subject-specific computational head model, using the material point method, built from T1 magnetic resonance images, and considering the anisotropic properties of the white matter which can predict strains in the brain under large rotational accelerations. The material model now includes the shear anisotropy of the white matter. We validate the model under head rotation and head extension motions using live human data, and advance a prior version of the model to include biofidelic falx and tentorium. We then examine the consequences of incorporating the falx and tentorium in terms of the predictions from the computational head model.

The Use of Ultrasound in Educational Settings: What Should We Consider When Implementing this Technique for Visualisation of Anatomical Structures?

Ultrasound is a well-established medical imaging technique with pioneering work conducted by Professor Ian Donald and his colleagues at the University of Glasgow, from the mid-1950s onwards, in terms of introducing it as a diagnostic tool in the field of obstetrics and gynaecology. Since then, ultrasound has been extensively used in clinical and research settings. There are few imaging techniques that have undergone such a fast and thriving evolution since their development. Nowadays, diagnostic ultrasound benefits from two-dimensional (2D), three-dimensional (3D), four-dimensional (4D), and a variety of Doppler modes with technologically advanced transducers (probes) producing images of high anatomical fidelity. In the future, there may even be a place for ultrasound in molecular imaging allowing for visualisationat the microscale. Ultrasound is characterised by real-time non-invasive scanning, relative ease of administration, and lack of ionising radiation. All of these features, make ultrasound an appealing option in educational settings for learning topographic anatomy and potentially enhancing future clinical practice for vocational learners. Sophisticated, but relatively inexpensive, portable handheld devices have also contributed to point-of-care ultrasound (POCUS) becoming the norm for bedside and pre-hospital scanning. It has been argued that ultrasound will become the next stethoscope for healthcare professionals. For this to become a reality, however, training is required on increasing familiarity with knobology, correct use of the machine and transducers, and accurate interpretation of anatomy followed by identification of pathologies. The above require incorporation of ultrasound teaching in undergraduate curricula, outwith the realm of opportunistic bedside learning, accompanied by consideration of ethical topics such as the management of incidental findings and careful evaluation of its pedagogical impact cross-sectionally and longitudinally.

The influence of osteoporotic bone structures of the pelvic-hip complex on stress distribution under impact load.

The aim of this study was to determine the effect of bone mineral density (BMD) on the stress distribution in pelvic-hip complex (PHC) model which included bone structures and soft tissues. Bone mass changes in osteoporosis and osteopenia were considered in this analysis. In addition, the relations between force direction and stress distribution causing PHC fractures were determined. This paper presents the development and validation of a detailed 3D finite element model with high anatomical fidelity of the PHC and BMD changes in trabecular and cortical bones, modelled based on CT scans. 10 kN loading was induced on a model consisting of 8 ligaments, the pelvis, sacrum, femur in front and side directions. For validation, the results of this model were compared to physiological stress in standing position and previous results with high-energy crashes under side impact load. Analysis of side-impact indicated the influence of BMD on femoral neck fractures, acetabular cartilage and sacroiliac joint delaminations. Front-impact analysis revealed the inferior pubic ramus, femoral neck fractures and soft tissue injuries, i.e., acetabular cartilage and symphysis pubis in osteoporosis and osteopenia. The elaborated PHC model enables effective prediction of pelvis injuries in high-energy trauma, according to Young-Burgess classification, and the determination of the influence of BMD reduction on pelvis trauma depending on force direction. The correlation between BMD and stress distribution causing varying injuries was determined.

Facilitation of bronchoscopy teaching with easily accessible low-cost 3D-printing

BackgroundBronchoscopy is a challenging skill and anaesthesia and pulmonologist societies recommend simulation for practicing. AimThe goal of this project was to develop a bronchoscopy simulator that allows critical-event simulation at low costs. MethodsFollowing written informed consent, we processed a human computer-tomography scan and extracted information about the bronchial tree. We then printed two bronchial trees in a 3D-printer in two different materials: hard polyamide and flexible photopolymer. The simulators were coated with silicone for a realistic appearance. Two independent airway expert consultant anaesthesiologists assessed the face validity of the simulators when compared to humans and to a commercially available bronchial tree simulator. ResultsThe two airway experts agreed on face validity and the 3D-simulators were deemed as highly comparable to the human anatomy, representing the human trachea and bronchial tree more realistically than the commercially available simulator. However, the flexible 3D-printed simulator was not satisfactory because the flexible texture allowed for easy damage of the silicone coat. ConclusionWe have described a simple method to create a low-cost bronchoscopy simulator with high anatomic fidelity using 3D-printing. The simulator features the ability to simulate advanced bronchoscopy tasks.

Development and Assessment of a Low-Cost 3D-printed Airway Model for Bronchoscopy Simulation Training.

We report upon the techniques used to create a plastic 3-dimensional-printed bronchoscopy trainer from an actual patient computed tomography scan. The formatting methods to create the printable file, using free open access software, are outlined. The resulting high anatomic fidelity part-task trainer is described, as well as experienced bronchoscopists' perception of its realism and utility as a training tool. A discussion of the current state of knowledge about the role of simulation in bronchoscopy training, as well as the potential contribution of this device, is presented.

Development and Validation of a High Anatomical Fidelity FE Model for the Buttock and Thigh of a Seated Individual.

Current practices for designing new cushions for seats depend on superficial measurements, such as pressure mapping, which do not provide sufficient information about the condition of sub-dermal tissues. Finite element (FE) modelling offers a unique alternative to integrate assessment of sub-dermal tissue condition into seat/cushion design and development processes. However, the development and validation of such FE models for seated humans requires accurate representation of the anatomy and material properties, which remain challenges that are yet to be addressed. This paper presents the development and validation of a detailed 3D FE model with high anatomical fidelity of the buttock and thigh, for a specific seated subject. The developed model consisted of 28 muscles, the pelvis, sacrum, femur, and one layer of inter-muscular fat, subcutaneous fat and skin. Validation against in vivo measurements from MRI data confirmed that the FE model can simulate the deformation of soft tissues under sitting loads with an accuracy of (mean±SD) 4.7±4.4mm. Simulation results showed that the maximum strains (compressive, shear and von-Mises) on muscles (41, 110, 79%) were higher than fat tissues (21, 62, 41%). The muscles that experienced the highest mechanical loads were the gluteus maximus, adductor magnus and muscles in the posterior aspect of the thighs (biceps femoris, semitendinosus and semimembranosus muscles). The developed FE model contributes to the progression towards bio-fidelity in modelling the human body in seated postures by providing insight into the distribution of stresses/strains in individual muscles and inter-muscular fat in the buttock and thigh of seated individuals. Industrial applications for the developed FE model include improving the design of office and household furniture, automotive and airplane seats and wheelchairs as well as customisation and assessment of sporting and medical equipment to meet individual requirements.

EIT Forward Problem Parallel Simulation Environment with Anisotropic Tissue and Realistic Electrode Models

Electrical impedance tomography (EIT) is an imaging technology based on impedance measurements. To retrieve meaningful insights from these measurements, EIT relies on detailed knowledge of the underlying electrical properties of the body. This is obtained from numerical models of current flows therein. The nonhomogeneous and anisotropic electric properties of human tissues make accurate modeling and simulation very challenging, leading to a tradeoff between physical accuracy and technical feasibility, which at present severely limits the capabilities of EIT. This work presents a complete algorithmic flow for an accurate EIT modeling environment featuring high anatomical fidelity with a spatial resolution equal to that provided by an MRI and a novel realistic complete electrode model implementation. At the same time, we demonstrate that current graphics processing unit (GPU)-based platforms provide enough computational power that a domain discretized with five million voxels can be numerically modeled in about 30 s.

WKA-1R Robot assisted quantitative assessment of airway management

The emerging field of medical robotics aims tointroduce intelligent tools for physician support. The main challenges for developing efficient medical robotic training systems are simulating real-world conditions of the task and assuring training effectiveness. High anatomic fidelity has been achieved in current systems, but they are limited to provide merely subjective assessments of the training progress. We simulated airway intubation using a unique medical robot and developed objective performance criteria to assess task performance. A patient simulation robot was designed to mimic real-world task conditions and provide objective assessments of training progress. The Waseda– Kyotokagaku Airway No. 1R (WKA-1R) includes a human patient model with embedded sensors. An evaluation function was developed for the WKA-1R to quantitatively assess task performance. The evaluation includes performance indices and coefficient weighting. The performance indices were defined based on experiments carried out with medical doctors and from information found in the medical literature. The performance indices are: intubation time, jaw opening, incisor teeth force, cuff pressure, tongue force and tube position. To determine the weighting of coefficients, we used discriminant analysis. Experiments were carried out with volunteers to determine the effectiveness of the WKA-1R to quantitatively evaluate their performance while performing airway management. We asked subjects from different levels of expertise (from anesthetists to unskilled) to perform the task. From the experimental results, we determined operator effectiveness using the proposed performance indices. We found a significant difference between the experimental groups by evaluating their performances using the proposed evaluation function (P < 0.05). The WKA-1R robot was designed to quantitatively acquire information on the performances of trainees during intubation procedures. From the experimental results, we could objectively determine operator effectiveness while providing quantitative task assessments.

Right-Angle Dental Radiography

Instruments have been designed which simplify and standardize the bisecting-angle and right-angle techniques for periapical radiography. Both can now be readily used in any office and easily taught to auxiliary personnel. Dimensional distortion is an unavoidable characteristic of bisecting-angle radiographs which may hinder an accurate interpretation and diagnosis. This is minimized in the right-angle technique, which produces radiographs of high anatomic fidelity. The right-angle technique is therefore recommended as the technique of choice.