Patient-specific Anatomy Research Articles

Left atrial decompression during veno-arterial extracorporeal membrane oxygenation using a single multi-stage drainage cannula with a transseptal approach: Clinical significance and medical management of LAVA ECMO

Extracorporeal Membrane Oxygenation (ECMO) is a life-support treatment used in critically ill patients that temporarily acts as the heart and lungs. It is used in numerous clinical scenarios where the patient’s heart and/or lungs are too sick to work on their own. With ECMO, a patient’s blood is removed from the body and pumped through an artificial lung, where oxygen is added and carbon dioxide is removed. There are two types of ECMO support: VV ECMO and VA ECMO. VV ECMO is used when a patient’s lungs need additional support, and VA ECMO is used when a patient’s heart and lungs need additional support. Although ECMO therapy can be life-saving, it is a supportive therapy, not a disease-modifying treatment. There are numerous techniques and strategies used to implement ECMO, all in which come with their own risks, complications, and possible emergencies. Cannulation strategy is determined by a multitude of factors, such as materials available, patient presentation, concurrent venous/arterial access, specific patient anatomy, clinical diagnosis, provider training, etc. One major complication specific to VA ECMO is left ventricular overload, which can create a lethal cascade of issues for a patient receiving this mode of support. This manuscript will discuss the products and materials needed, cannulation techniques, configurations, and clinical significance of left atrial veno-arterial extracorporeal membrane oxygenation (LAVA ECMO). We will focus on clinical scenarios that allow for LAVA ECMO and unique considerations for this complex cannulation strategy. Additionally, we will address the use of LAVA ECMO in patients where traditional left atrial venting and decompression techniques are contraindicated. Finally, current data pertaining to patient outcomes related to the use of LAVA ECMO will be discussed in length, giving a synopsis of the benefits of using a single multi-stage drainage cannula with a transseptal approach for left atrial decompression in VA ECMO

Multiphysics simulations reveal haemodynamic impacts of patient-derived fibrosis-related changes in left atrial tissue mechanics.

Stroke is a leading cause of death and disability worldwide. Atrial myopathy, including fibrosis, is associated with an increased risk of ischaemic stroke, but the mechanisms underlying this association are poorly understood. Fibrosis modifies myocardial structure, impairing electrical propagation and tissue biomechanics, and creating stagnant flow regions where clots could form. Fibrosis can be mapped non-invasively using late gadolinium enhancement magnetic resonance imaging (LGE-MRI). However, fibrosis maps are not currently incorporated into stroke risk calculations or computational electro-mechano-fluidic models. We present multiphysics simulations of left atrial (LA) myocardial motion and haemodynamics using patient-specific anatomies and fibrotic maps from LGE-MRI. We modify tissue stiffness and active tension generation in fibrotic regions and investigate how these changes affect LA flow for different fibrotic burdens. We find that fibrotic regions and, to a lesser extent, non-fibrotic regions experience reduced myocardial strain, resulting in decreased LA emptying fraction consistent with clinical observations. Both fibrotic tissue stiffening and hypocontractility independently reduce LA function, but, together, these two alterations cause more pronounced effects than either one alone. Fibrosis significantly alters flow patterns throughout the atrial chamber, and particularly, the filling and emptying jets of the left atrial appendage (LAA). The effects of fibrosis in LA flow are largely captured by the concomitant changes in LA emptying fraction except inside the LAA, where a multifactorial behaviour is observed. This work illustrates how high-fidelity, multiphysics models can be used to study thrombogenesis mechanisms in patient-specific anatomies, shedding light onto the links between atrial fibrosis and ischaemic stroke. KEY POINTS: Left atrial (LA) fibrosis is associated with arrhythmogenesis and increased risk of ischaemic stroke; its extent and pattern can be quantified on a patient-specific basis using late gadolinium enhancement magnetic resonance imaging. Current stroke risk prediction tools have limited personalization, and their accuracy could be improved by incorporating patient-specific information such as fibrotic maps and haemodynamic patterns. We present the first electro-mechano-fluidic multiphysics computational simulations of LA flow, including fibrosis and anatomies from medical imaging. Mechanical changes in fibrotic tissue impair global LA motion, decreasing LA and left atrial appendage (LAA) emptying fractions, especially in subjects with higher fibrosis burdens. Fibrotic-mediated LA motion impairment alters LA and LAA flow near the endocardium and the whole cavity, ultimately leading to more stagnant blood regions in the LAA.

“Frontal Sinus Setback in Facial Feminization Surgery: Emphasizing Anatomical Landmarks Over Virtual Planning and Cutting Guides”

Background: Demand for facial feminization surgery (FFS) is growing amidst increasing recognition of its significant impact on gender affirmation. Forehead contouring via frontal sinus setback is a powerful procedure for feminizing the upper facial skeleton. While Virtual Surgical Planning (VSP) has been described as a useful tool in these surgeries, the associated cost may limit access for patients seeking these transformative interventions, especially those who lack insurance coverage for FFS. This study challenges the emerging notion that VSP is critical for the successful execution of frontal sinus setbacks. Methods: We present a technique that relies on well-defined anatomical landmarks of the frontal sinus and standard maxillofacial CT imaging for pre-operative planning, eliminating the need for expensive, pre-operatively prepared cutting guides. Key steps in this technique include obtaining detailed measurements of the frontal sinus dimensions and contour, visualizing the nasofrontal junction, reshaping the frontal sinus, resecting the corrugator muscle, and finally, performing a direct browlift. Results: In our cohort of 13 patients, including a 65-year-old transgender female with significant forehead prominence, this approach consistently achieved satisfactory outcomes without complications. Conclusion: By demonstrating that high-quality results can be achieved without VSP, we present a cost-conscious approach to FFS for a more inclusive and equitable provision to gender-affirming care. Surgical expertise and understanding of patient-specific anatomy are crucial in achieving these results, emphasizing the importance of skill over reliance on technology.

Ostial LCx: Achilles Heel of Left Main Bifurcation Angioplasty and How We Evolved in Its Management

In-stent restenosis (ISR) within bifurcation lesions of the left main (LM) coronary artery (LMCA) is challenging due to its complex anatomy and critical function. This case series highlights 3 patients with LM bifurcation ISR (Medina 1,1,1) post-index intervention using different stent strategies as follows: Case 1: A 58-year-old male developed distal LM bifurcation stenosis after ostial left anterior descending artery (LAD) stenting. Mini-culotte bifurcation angioplasty effectively managed this. Case 2: A 62-year-old male presented with neo-atherosclerosis-induced distal LM bifurcation ISR post-provisional LM-left anterior descending artery (LAD) stenting. A single-stent crossover with a drug-coated balloon in a large side branch achieved optimal flow restoration. Case 3: A chronic total occlusion in the right coronary artery and distal LM bifurcation ISR due to stent overhang into LMCA in a 72-year-old male was resolved with a string culotte technique. These cases underscore ISR management strategies tailored to patient-specific anatomy and clinical needs, advocating advanced imaging techniques like intravascular ultrasound and optical coherence tomography for procedural precision and safety.

Thrombogenic Risk Assessment of Transcatheter Prosthetic Heart Valves Using a Fluid-Structure Interaction Approach

Background and ObjectiveProsthetic heart valve interventions such as TAVR have surged over the past decade, but the associated complication of long-term, life-threatening thrombotic events continues to undermine patient outcomes. Thus, improving thrombogenic risk analysis of TAVR devices is crucial. In vitro studies for thrombogenicity are typically difficult to perform. However, revised ISO testing standards include computational testing for thrombogenic risk assessment of cardiovascular implants. We present a fluid-structure interaction (FSI) approach for assessing thrombogenic risk of transcatheter aortic valves. MethodsAn FSI framework was implemented via the incompressible computational fluid dynamics multi-physics solver of the ANSYS LS-DYNA software. The numerical modeling approach for flow analysis was validated by comparing the derived flow rate of the 29 mm CoreValve device from benchtop testing and orifice areas of commercial TAVR valves in the literature to in silico results. Thrombogenic risk was analyzed by computing stress accumulation (SA) on virtual platelets seeded in the flow fields via ANSYS EnSight. The integrated FSI-thrombogenicity methodology was subsequently employed to examine hemodynamics and thrombogenic risk of TAVR devices with two approaches: 1) engineering optimization and 2) clinical assessment. ResultsSimulated effective orifice areas for commercial valves were in reported ranges. In silico cardiac output and flow rate during the positive pressure differential period matched experimental results by approximately 93 %. The approach was used to analyze the effect of various TAVR leaflet designs on hemodynamics, where platelets experienced instantaneous stresses reaching around 10 Pa. Post-TAVR deployment hemodynamics in patient-specific bicuspid aortic valve anatomies revealed varying degrees of thrombogenic risk with the highest median SA around 70 dyn·s/cm2 - nearly double the activation threshold - despite those being clinically classified as “mild” paravalvular leaks. ConclusionsOur methodology can be used to improve the thromboresistance of prosthetic valves from the initial design stage to the clinic. It allows for unparalleled optimization of devices, uncovering key TAVR leaflet design parameters that can be used to mitigate thrombogenic risk, in addition to patient-specific modeling to evaluate device performance. This work demonstrates the utility of advanced in silico analysis of TAVR devices that can be utilized for thrombogenic risk assessment of other blood recirculating devices.

Use of Mixed Reality Technologies by Orthopedic Surgery Residents: A Cross-Sectional Study of Trainee Perceptions

Introduction Recently within surgical education, the development of extended reality (XR) devices has become a topic of interest to improve trainees’ surgical technique outside of the operating room. There is a growing body of literature which supports the use of XR, and it is important to understand the perceptions of orthopedic surgery trainees on the use of XR as an adjunct during training. Purpose Understand the perceptions of orthopedic trainees on the use of XR as an adjunctive surgical training tool. Methods An internally validated 18-question survey was sent to all US orthopedic residency program coordinators with the intent for distribution to each program’s respective residents. Responses with ≥ 70% completion were considered complete. Results Overall, 33% and 18% of residents agreed XR is needed, and all programs should offer XR, respectively. There was overall agreement (67%) for XR’s ability to improve procedural confidence and improve skill progression (65% agreed). Only 25% of respondents felt XR could accurately simulate orthopedic procedures and 36% agreed it could effectively model patient-specific anatomy for preoperative planning. Regarding XR’s ability to reduce intraoperative navigational error, 45% of respondents agreed. However, responses were more neutral for XR’s ability to reduce inpatient length of stay (40%) and ability to improve the accuracy of hardware/prosthetic placement (31%). Finally, 53% of respondents agreed that the largest barrier to integration of XR is cost, while 35% felt that a lack of dedicated time to use the technology during their training program was a major barrier. Conclusion The need for adjunctive surgical training outside of the operating room is clearly demonstrated from our results. Although it is unclear if XR will become a standard tool across all residency programs, orthopedic surgery residents do feel that the technology is useful in terms of skills progression and operative confidence. Thus, this study provides a preliminary framework which suggests a potential role for XR in orthopedic surgery training and the need for further study to address barriers to widespread integration.

High accuracy of component positioning and restoration of lower limb alignment using robotic medial unicompartmental knee arthroplasty.

Unicondylar arthroplasty was performed using robotic medial unicompartmental knee arthroplasty (R-mUKA) and gap-balancing instrumentation. Our hypothesis was that robotic unicondylar knee arthroplasty accurately restores component positioning and lower limb alignment when compared to preoperative planning with actual implantation throughout the range of knee motion due to proper knee balancing. Data were collected prospectively and were analysed for patients undergoing RM-UKA. A cemented UKA was implanted using the MAKO® robotic system. Lower limb alignment at 0°, 30°, 45°, 60° and 90° of flexion was recorded of the native knee, with the trial components in place and finally after component implantation. A spacer according to the femorotibial gap was introduced and the alignment was measured. The position of the final component was planned based on three-dimensional computed tomography images before making the bone cuts. The positioning of the femoral and tibial components was analysed in all three planes. A total of 52 patients were included (mean age 66.3 ± 6.7 years; 34 males, 18 females). The difference in femoral component position after planning and final implantation was 0.04° ± 0.58° more valgus in the coronal plane (p = 0.326) and 0.6° ± 1.4° more flexion relative to the sagittal plane (p = 0.034). The tibial component was placed in the coronal plane in 0.3° ± 0.8° of more varus (p = 0.113) and in the sagittal plane in 0.6° ± 1.2° of more posterior tibial slope (p = 0.001). Lower limb alignment of the native knee in extension was 5.8° ± 2.6° of varus and changed to 3° ± 2.1° varus after UKA (p ≤ 0.01). R-mUKA helps to achieve the target of alignment and component position without any significant differences to the planning. Ligament balancing causes non-significant changes in component position. It allows optimal component position even for off-the-shelf implants respecting the patient's specific anatomy. II.

Leveraging digital twins for improved orthopaedic evaluation and treatment.

The purpose of this article is to explore the potential of digital twin technologies in orthopaedics and to evaluate how their integration with artificial intelligence (AI) and deep learning (DL) can improve orthopaedic evaluation and treatment. This review addresses key applications of digital twins, including surgical planning, patient-specific outcome prediction, augmented reality-assisted surgery and simulation-based surgical training. Existing studies on digital twins in various domains, including engineering, biomedical and orthopaedics are reviewed. We also reviewed advancements in AI and DL relevant to digital twins. We focused on identifying key benefits, challenges and future directions for the implementation of digital twins in orthopaedic practice. The review highlights that digital twins offer significant potential to revolutionise orthopaedic care by enabling precise surgical planning, real-time outcome prediction and enhanced training. Digital twins can model patient-specific anatomy using advanced imaging techniques and dynamically update with real-time data, providing valuable insights during surgery and postoperative care. However, challenges such as the need for large-scale data sets, technological limitations and integration issues must be addressed to fully realise these benefits. Digital twins represent a promising frontier in orthopaedic research and practice, with the potential to improve patient outcomes and enhance surgical precision. To enable widespread adoption, future research must focus on overcoming current challenges and further refining the integration of digital twins with AI and DL technologies. Level V.

Validation evidence with experimental and clinical data to establish credibility of TAVI patient-specific simulations

PurposeThe objective of this study is to validate a novel workflow for implementing patient-specific finite element (FE) simulations to virtually replicate the Transcatheter Aortic Valve Implantation (TAVI) procedure. MethodsSeven patients undergoing TAVI were enrolled. Patient-specific anatomical models were reconstructed from pre-operative computed tomography (CT) scans and subsequentially discretized, considering the native aortic leaflets and calcifications. Moreover, high-fidelity models of CoreValve Evolut R and Acurate Neo2 valves were built. To determine the most suitable material properties for the two stents, an accurate calibration process was undertaken. This involved conducting crimping simulations and fine-tuning Nitinol parameters to fit experimental force-diameter curves. Subsequently, FE simulations of TAVI procedures were conducted. To validate the reliability of the implemented implantation simulations, qualitative and quantitative comparisons with post-operative clinical data, such as angiographies and CT scans, were performed. ResultsFor both devices, the simulation curves closely matched the experimental data, indicating successful validation of the valves mechanical behaviour. An accurate qualitative superimposition with both angiographies and CTs was evident, proving the reliability of the simulated implantation. Furthermore, a mean percentage difference of 1,79 ± 0,93 % and 3,67 ± 2,73 % between the simulated and segmented final configurations of the stents was calculated in terms of orifice area and eccentricity, respectively. ConclusionThis study shows the successful validation of TAVI simulations in patient-specific anatomies, offering a valuable tool to optimize patients care through personalized pre-operative planning. A systematic approach for the validation is presented, laying the groundwork for enhanced predictive modeling in clinical practice.

Development and assessment of case-specific physical and augmented reality simulators for intracranial aneurysm clipping

BackgroundMicrosurgical clipping is a delicate neurosurgical procedure used to treat complex Unruptured Intracranial Aneurysms (UIAs) whose outcome is dependent on surgeon’s experience. Simulations are emerging as excellent complements to standard training, but their adoption is limited by the realism they provide. The aim of this study was to develop and validate a microsurgical clipping simulator platform.MethodsPhysical and holographic simulators of UIA clipping have been developed. The physical phantom consisted of a 3D printed hard skull and five (n = 5) rapidly interchangeable, perfused and fluorescence compatible 3D printed aneurysm silicone phantoms. The holographic clipping simulation included a real-time finite-element-model of the aneurysm sac, allowing interaction with a virtual clip and its occlusion. Validity, usability, usefulness and applications of the simulators have been assessed through clinical scores for aneurysm occlusion and a questionnaire study involving 14 neurosurgical residents (R) and specialists (S) for both the physical (p) and holographic (h) simulators by scores going from 1 (very poor) to 5 (excellent).ResultsThe physical simulator allowed to replicate successfully and accurately the patient-specific anatomy. UIA phantoms were manufactured with an average dimensional deviation from design of 0.096 mm and a dome thickness of 0.41 ± 0.11 mm. The holographic simulation executed at 25–50 fps allowing to gain unique insights on the anatomy and testing of the application of several clips without manufacturing costs. Aneurysm closure in the physical model evaluated by fluorescence simulation and post-operative CT revealed Raymond 1 (full) occlusion respectively in 68.89% and 73.33% of the cases. For both the simulators content validity, construct validity, usability and usefulness have been observed, with the highest scores observed in clip selection usefulness Rp=4.78, Sp=5.00 and Rh=4.00, Sh=5.00 for the printed and holographic simulators.ConclusionsBoth the physical and the holographic simulators were validated and resulted usable and useful in selecting valid clips and discarding unsuitable ones. Thus, they represent ideal platforms for realistic patient-specific simulation-based training of neurosurgical residents and hold the potential for further applications in preoperative planning.

Intracranial bypass for giant aneurysms treatment assessed by computational fluid dynamics (CFD) analysis

Unruptured giant intracranial aneurysms (GIA) are those with diameters of 25 mm or greater. As aneurysm size is correlated with rupture risk, GIA natural history is poor. Parent artery occlusion or trapping plus bypass revascularization should be considered to encourage intra-aneurysmal thrombosis when other treatment options are contraindicated. The mechanistic background of these methods is poorly studied. Thus, we assessed the potential of computational fluid dynamics (CFD) and fluid–structure interaction (FSI) analyses for clinical use in the preoperative stage. A CFD investigation in three patient-specific flexible models of whole arterial brain circulation was performed. A C6 ICA segment GIA model was created based on CT angiography. Two models were then constructed that simulated a virtual bypass in combination with proximal GIA occlusion, but with differing middle cerebral artery (MCA) recipient vessels for the anastomosis. FSI and CFD investigations were performed in three models to assess changes in flow pattern and haemodynamic parameters alternations (wall shear stress (WSS), oscillatory shear index (OSI), maximal time averaged WSS (TAWSS), and pressure). General flow splitting across the entire domain was affected by virtual bypass procedures, and any deficiency was partially compensated by a specific configuration of the circle of Willis. Following the implementation of bypass procedures, a reduction in haemodynamic parameters was observed within the aneurysm in both cases under analysis. In the case of the temporal MCA branch bypass, the decreases in the studied parameters were slightly greater than in the frontal MCA branch bypass. The reduction in the magnitude of the chosen area-averaged parameters (averaged over the aneurysm wall surface) was as follows: WSS 35.7%, OSI 19.0%, TAWSS 94.7%, and pressure 24.2%. FSI CFD investigation based on patient-specific anatomy models with subsequent stimulation of virtual proximal aneurysm occlusion in conjunction with bypass showed that this method creates a pro-thrombotic favourable environment whilst reducing intra-aneurysmal pressure leading to shrinking. MCA branch recipient selection for optimum haemodynamic conditions should be evaluated individually in the preoperative stage.

Virtual Reality as an Adjunct to Traditional Patient Counseling in Patients With Newly Diagnosed Localized Prostate Cancer

ObjectivesTo determine the utility of a virtual reality (VR) model constructed using patient-derived clinical imaging to improve patient understanding of localized prostate cancer (PCa) diagnosis and surgical plan. MethodsPatients undergoing robotic radical prostatectomy were selected and demographic data recorded. Patients completed a questionnaire to assess baseline knowledge of their diagnosis after consultation and shared-decision making with their surgeon. A trained non-clinical staff member then guided the patient through a VR experience to view patient-specific anatomy in a 3-dimensional space. Patients then completed the same questionnaire, followed by an additional post-VR questionnaire evaluating patient satisfaction. Questions 1-7 (patient understanding of prostate cancer and treatment plan) and 11-17 (patient opinion of VR) used a standard Likert scale and Questions 8-10 were multiple choice with 1 correct answer. ResultsIn total, 15 patients were included with an average age of 64.1 years. 6 of 7 questions showed an improvement after VR (p<0.001). The percentage of correct responses on Questions 8-10 were higher after VR but not statistically significant (p>0.13). Mean responses range from 4.3 to 4.8 (Likert scale, 1 through 5) for the post-VR questionnaire, with a mean total of 31.9 out of 35. ConclusionThis small preliminary investigation of a novel technology to improve the patient experience showed potential as an adjunct to traditional patient counseling. However, due the small sample size and study design, further research is needed to determine the value VR adds to prostate cancer surgical counselling.

Development of a patient-specific model of the human coronary system for percutaneous transluminal coronary angioplasty balloon catheter training and testing

BackgroundTo treat stenosed coronary arteries, percutaneous transluminal coronary angioplasty (PTCA) balloon catheters must combine pushability, trackability, crossability, and rewrap behavior. The existing anatomic track model (ASTM F2394) for catheter testing lacks 3D morphology, vessel tortuosity, and compliance, making evaluating performance characteristics difficult. This study aimed to develop a three-dimensional patient-specific phantom (3DPSP) for device testing and safe training for interventional cardiologists.MethodsA range of silicone materials with different shore hardnesses (00–30–45 A) and wall thicknesses (0.5 mm, 1 mm, 2 mm) were tested to determine compliance for creating coronary vessel phantoms. Compliance was assessed using optical coherence tomography (OCT) and compared to values in the literature. Stenosis was induced using multilayer casting and brushing methods, with gypsum added for calcification. The radial tensile properties of the samples were investigated, and the relationship between Young’s modulus and compliance was determined. Various methods have been introduced to approximate the friction between silicone and real coronary vessel walls. Computerized tomography (CT) scans were used to obtain patient-specific anatomy from the femoral artery to the coronary arteries. Artery lumens were segmented from the CT scans to create dissolvable 3D-printed core models.ResultsA 15A shore hardness silicone yielded an experimental compliance of 12.3–22.4 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document} for stenosed tubes and 14.7–57.9 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document} for uniform tubes, aligning closely with the literature data (6.28–40.88 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document}). The Young’s modulus ranged from 43.2 to 75.5 kPa and 56.6–67.9 kPa for the uniform and calcified materials, respectively. The dependency of the compliance on the wall thickness, Young’s modulus, and inner diameter could be shown. Introducing a lubricant reduced the silicone friction coefficient from 0.52 to 0.13. The 3DPSP was successfully fabricated, and comparative analyses were conducted among eight commercially available catheters.ConclusionThis study presents a novel method for crafting 3DPSPs with realistic mechanical and frictional properties. The proposed approach enables the creation of comprehensive and anatomically precise setups spanning the right femoral artery to the coronary arteries, highlighting the importance of such realistic environments for advancing medical device development and fostering safe training conditions.

The Use of 3D Printing in Fetal Surgery for Surgical Planning: A Scoping Review.

Objectives: We sought to identify in which clinical scenarios 3D printed models are used to plan for fetal surgeries as well as the main purpose and the imaging method utilized for the models. In addition, we describe benefits and shortcomings of the models, as well as potential future improvements. Methods: In this scoping review, data were collected retrospectively from scientific databases (PubMed, Embase, Cochrane CENTRAL, CINAHL, Scopus, and the Web of Science platform) and screened by title, abstract, and full text against strict criteria. The inclusion criteria required the study be performed on a live fetus and involve 3D models used for fetal surgery. The models must have been designed from diagnostic imaging modalities such as CT, MRI, or ultrasound. The articles considered include clinical trials, review articles, cohort studies, case series, case reports, and conference abstracts. Results: Of the initial 742 articles collected, six met the inclusion criteria. Spina bifida and EXIT procedures were the most frequent use cases that inspired surgeons to print models for surgical planning. The ability to view patient-specific anatomy in a 3D handheld model was often touted as providing a great benefit to the surgical team's ability to anticipate intraoperative challenges. Conclusions: Three-dimensional printing models have been applied to plan for fetal surgeries, more specifically, for EXIT procedures and fetoscopic surgical repair of spina bifida. The potential benefits of 3D printing in fetal surgery are enormous.

Evaluation of the superior pubic ramus and supra acetabular corridors using statistical shape modelling.

The incidence of osteoporotic pelvic fractures is increasing. The broken anterior pelvic ring is preferentially fixed with long intramedullary screws, which require a good understanding of the patient-specific anatomy to prevent joint perforation. The aim of this study was to assess the variability of the superior pubic ramus and the supra acetabular corridors' length and width using statistical shape modelling. A male and female statistical shape model was made based on 59 forensic CT scans. For the superior pubic ramus and the supra acetabular corridor the longest and widest completely fitting cylinder was created for the first 5 principal components (PC) of both models, male and female pelvises separately. A total of 59 pelvises were included in this study of which 36 male and 23 female. The first 5 principal components explained 75% and 79% of the pelvic variation in males and females, respectively. Within 3 PCs of the female statistical shape model (SSM) a superior pubic ramus corridor of < 7.3mm was found, 5.5mm being the narrowest linear corridor measured. Both corridors in all PCs of the male SSM measured > 7.3mm. Within females a 7.3mm and 6.5mm screw won't always fit in the superior pubic ramus corridor, especially if a flat sacrum, a small pelvis or a wide subpubic angle are present. The supra acetabular corridor did not seem to have sex-specific differences. In the supra-acetabular corridor there was always enough space to accommodate a 7.3mm screw, both in males and females.

4-Dimensional Right Ventricular Outflow Tract Segmentation to Evaluate Candidacy for Transcatheter Pulmonary Valve Replacement.

Candidacy for transcatheter pulmonary valve replacement utilizing newer valve platforms is aided by industry-driven fit analyses. We report augmentation of this decision-making process by visualization of 4-dimensional cine imaging of patient-specific right ventricular outflow tract anatomy and a virtual valve model within a virtual reality platform.

Leveraging the Apple Ecosystem: Easy Viewing and Sharing of Three-dimensional Perforator Visualizations via iPad/iPhone-based Augmented Reality

Summary: We introduce a novel technique using augmented reality (AR) on smartphones and tablets, making it possible for surgeons to review perforator anatomy in three dimensions on the go. Autologous breast reconstruction with abdominal flaps remains challenging due to the highly variable anatomy of the deep inferior epigastric artery. Computed tomography angiography has mitigated some but not all challenges. Previously, volume rendering and different headsets were used to enable better three-dimensional (3D) review for surgeons. However, surgeons have been dependent on others to provide 3D imaging data. Leveraging the ubiquity of Apple devices, our approach permits surgeons to review 3D models of deep inferior epigastric artery anatomy segmented from abdominal computed tomography angiography directly on their iPhone/iPad. Segmentation can be performed in common radiology software. The models are converted to the universal scene description zipped format, which allows immediate use on Apple devices without third-party software. They can be easily shared using secure, Health Insurance Portability and Accountability Act–compliant sharing services already provided by most hospitals. Surgeons can simply open the file on their mobile device to explore the images in 3D using “object mode” natively without additional applications or can switch to AR mode to pin the model in their real-world surroundings for intuitive exploration. We believe patient-specific 3D anatomy models are a powerful tool for intuitive understanding and communication of complex perforator anatomy and would be a valuable addition in routine clinical practice and education. Using this one-click solution on existing devices that is simple to implement, we hope to streamline the adoption of AR models by plastic surgeons.

Stability of Dexamethasone during Hot-Melt Extrusion of Filaments based on Eudragit® RS, Ethyl Cellulose and Polyethylene Oxide

Hot-melt extrusion (HME) potentially coupled with 3D printing is a promising technique for the manufacturing of dosage forms such as drug-eluting implants which might even be individually adapted to patient-specific anatomy. However, these manufacturing methods involve the risk of thermal degradation of incorporated drugs during processing. In this work, the stability of the anti-inflammatory drug dexamethasone (DEX) was studied during HME using the polymers Eudragit® RS, ethyl cellulose and polyethylene oxide. The extrusion process was performed at different temperatures. Furthermore, the influence of accelerated screw speed, the addition of the plasticizers triethyl citrate and polyethylene glycol 6000 or the addition of the antioxidants butylated hydroxytoluene and tocopherol in two concentrations were studied. The DEX recovery was analyzed by a high performance liquid chromatography method suitable for the detection of thermal degradation products. The strongest impact on the drug stability was found for the processing temperature, which was found to reduce the DEX recovery to <20% for certain processing conditions. In addition, differences between tested polymers were observed, whereas the use of additives did not result in remarkable changes in drug stability. In conclusion, suitable extrusion parameters were identified for the processing of DEX with high drug recovery rates for the tested polymers. Moreover, the importance of a suitable analysis method for drug stability during HME that is influenced by several parameters was highlighted.

Image2Flow: A proof-of-concept hybrid image and graph convolutional neural network for rapid patient-specific pulmonary artery segmentation and CFD flow field calculation from 3D cardiac MRI data.

Computational fluid dynamics (CFD) can be used for non-invasive evaluation of hemodynamics. However, its routine use is limited by labor-intensive manual segmentation, CFD mesh creation, and time-consuming simulation. This study aims to train a deep learning model to both generate patient-specific volume-meshes of the pulmonary artery from 3D cardiac MRI data and directly estimate CFD flow fields. This proof-of-concept study used 135 3D cardiac MRIs from both a public and private dataset. The pulmonary arteries in the MRIs were manually segmented and converted into volume-meshes. CFD simulations were performed on ground truth meshes and interpolated onto point-point correspondent meshes to create the ground truth dataset. The dataset was split 110/10/15 for training, validation, and testing. Image2Flow, a hybrid image and graph convolutional neural network, was trained to transform a pulmonary artery template to patient-specific anatomy and CFD values, taking a specific inlet velocity as an additional input. Image2Flow was evaluated in terms of segmentation, and the accuracy of predicted CFD was assessed using node-wise comparisons. In addition, the ability of Image2Flow to respond to increasing inlet velocities was also evaluated. Image2Flow achieved excellent segmentation accuracy with a median Dice score of 0.91 (IQR: 0.86-0.92). The median node-wise normalized absolute error for pressure and velocity magnitude was 11.75% (IQR: 9.60-15.30%) and 9.90% (IQR: 8.47-11.90), respectively. Image2Flow also showed an expected response to increased inlet velocities with increasing pressure and velocity values. This proof-of-concept study has shown that it is possible to simultaneously perform patient-specific volume-mesh based segmentation and pressure and flow field estimation using Image2Flow. Image2Flow completes segmentation and CFD in ~330ms, which is ~5000 times faster than manual methods, making it more feasible in a clinical environment.

Advancements in surgical education: exploring animal and simulation models in fetal and neonatal surgery training.

Surgical education is undergoing a transformation, moving away from traditional models towards more modern approaches that integrate experiential and didactic methods. This shift is particularly pertinent in the realm of fetal and neonatal surgery, where specialized training is crucial. Historical training methods, such as cadaveric dissection, have been prevalent for centuries, but newer innovations, including animal and non-animal simulation models, are gaining prominence. This manuscript aims to explore the use of both animal and non-animal models in surgical education, with a specific focus on fetal and neonatal surgery. The use of animal models in surgical training has a long history, dating back to Halsted's introduction in 1889. These models, often utilizing large animals like swine and dogs, offer valuable insights into fetal and neonatal surgeries. They allow for the study of long-term outcomes and the simulation of various diseases and anomalies, providing essential training experiences not readily available in human surgeries. However, there are notable limitations, including anatomical and physiological differences from humans, ethical considerations, and substantial infrastructure and maintenance costs. Simulation-based training offers several benefits, including standardized and safe learning environments without risks to real patients. Bench models, using synthetic materials or non-living animal tissue, provide cost-effective options for skills development. Virtual reality and 3-D printing technologies further enhance simulation experiences, allowing for the replication of complex clinical scenarios and patient-specific anatomies. While these models offer significant advantages, they lack the complexity of biological systems found in animal models. In conclusion, both animal and non-animal simulation models play crucial roles in enhancing surgical education, particularly in fetal and neonatal surgery. While advancements in non-animal technologies are important for ethical reasons, the continued necessity of animal models in certain areas should be acknowledged. By responsibly integrating these models into training programs, surgical education can be further enriched while upholding ethical standards and ensuring optimal patient outcomes.