Patient-specific Anatomical Models Research Articles

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.

Utility of 3D-Printed Models in the Surgical Planning for Primary Spine Tumors: A Survey of International Spinal Oncology Experts.

Survey study. The purpose of this study was to characterize the utility of 3D printed patient specific anatomic models for the planning of complex primary spine tumor surgeries. A survey of individual members of an international study group of spinal oncology surgeons was performed. Participants were provided a clinical vignette, pathologic diagnosis, and pre-operative imaging for three primary spinal oncology cases. Study participants provided a free text surgical plan for resection and were then presented an associated 3D printed model for each case and asked to re-evaluate their surgical plan. Ten spinal oncology surgeons participated in the study, representing nine institutions across five countries. Four of the surgeons (40%) made significant changes to their surgical plan after reviewing the 3D models, including sacrifice of an additional nerve root to obtain negative margins, sparing an SI joint that was originally planned for inclusion in the en bloc resection, adjusting the location of osteotomy cuts, changes to the number of surgical stages and/or staging order, and preservation of neurology that was originally planned for sacrifice. The overall impression of the 3D models was positive, with 90% of the participants stating they found the 3D model useful in developing a surgical plan. Surgical planning for resection of primary spinal column tumors is challenging and time intensive. 3D printed patient specific surgical models may be an additional tool that can augment surgical planning and execution by improving the chance of accomplishing surgical resection goals and minimizing morbidity.

Three-dimensional-printing-guided preoperative planning of upper and lower extremity pediatric orthopedic surgeries: A systematic review of surgical outcomes.

Three-dimensional printing has evolved into a cost-effective and accessible tool. In orthopedic surgery, creating patient-specific anatomical models and instrumentation improves visualization and surgical accuracy. In pediatric orthopedics, three-dimensional printing reduces operating time, radiation exposure, and blood loss by enhancing surgical efficacy. This review compares outcomes of three-dimensional printing-assisted surgeries with conventional surgeries for upper and lower extremity pediatric surgeries. A complete search of medical literature up to August 2023, using Ovid Medline, EMBASE, Scopus, Web of Science, and Cochrane Library was conducted in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Broad search terms included "pediatrics," "orthopedic," and "3D-printing." Eligible studies were assessed for intraoperative time, blood loss, and fluoroscopy exposure. Out of 3299 initially identified articles, 14 articles met inclusion criteria. These studies included 409 pediatric patients, with ages averaging 9.51 years. The majority were retrospective studies (nine), with four prospective and one experimental study. Studies primarily utilized three-dimensional printing for navigation templates and implants. Results showed significant reductions in operative time, blood loss, and radiation exposure with three-dimensional printing. Complication occurrences were generally lower in three-dimensional printing surgeries, but there was no statistical significance. Three-dimensional printing is an emerging technology in the field of orthopedics, and it is primarily used for preoperative planning. For pediatric upper and lower extremity surgeries, three-dimensional printing leads to decreased operating room time, decreased intraoperative blood loss, and reduced radiation exposure. Other uses for three-dimensional printing include education, patient communication, the creation of patient-specific instrumentation and implants. Level III.

Exploring CT pixel and voxel size effect on anatomic modeling in mandibular reconstruction

BackgroundComputer-aided modeling and design (CAM/CAD) of patient anatomy from computed tomography (CT) imaging and 3D printing technology enable the creation of tangible, patient-specific anatomic models that can be used for surgical guidance. These models have been associated with better patient outcomes; however, a lack of CT imaging guidelines risks the capture of unsuitable imaging for patient-specific modeling. This study aims to investigate how CT image pixel size (X-Y) and slice thickness (Z) impact the accuracy of mandibular models.MethodsSix cadaver heads were CT scanned at varying slice thicknesses and pixel sizes and turned into CAD models of the mandible for each scan. The cadaveric mandibles were then dissected and surface scanned, producing a CAD model of the true anatomy to be used as the gold standard for digital comparison. The root mean square (RMS) value of these comparisons, and the percentage of points that deviated from the true cadaveric anatomy by over 2.00 mm were used to evaluate accuracy. Two-way ANOVA and Tukey-Kramer post-hoc tests were used to determine significant differences in accuracy.ResultsTwo-way ANOVA demonstrated significant difference in RMS for slice thickness but not pixel size while post-hoc testing showed a significant difference in pixel size only between pixels of 0.32 mm and 1.32 mm. For slice thickness, post-hoc testing revealed significantly smaller RMS values for scans with slice thicknesses of 0.67 mm, 1.25 mm, and 3.00 mm compared to those with a slice thickness of 5.00 mm. No significant differences were found between 0.67 mm, 1.25 mm, and 3.00 mm slice thicknesses. Results for the percentage of points deviating from cadaveric anatomy greater than 2.00 mm agreed with those for RMS except when comparing pixel sizes of 0.75 mm and 0.818 mm against 1.32 mm in post-hoc testing, which showed a significant difference as well.ConclusionThis study suggests that slice thickness has a more significant impact on 3D model accuracy than pixel size, providing objective validation for guidelines favoring rigorous standards for slice thickness while recommending isotropic voxels. Additionally, our results indicate that CT scans up to 3.00 mm in slice thickness may provide an adequate 3D model for facial bony anatomy, such as the mandible, depending on the clinical indication.

PyCEPS: A cross-platform electroanatomic mapping data to computational model conversion platform for the calibration of digital twin models of cardiac electrophysiology

Background and Objective:Data from electro-anatomical mapping (EAM) systems are playing an increasingly important role in computational modeling studies for the patient-specific calibration of digital twin models. However, data exported from commercial EAM systems are challenging to access and parse. Converting to data formats that are easily amenable to be viewed and analyzed with commonly used cardiac simulation software tools such as openCARP remains challenging. We therefore developed an open-source platform, pyCEPS, for parsing and converting clinical EAM data conveniently to standard formats widely adopted within the cardiac modeling community. Methods and Results:pyCEPS is an open-source Python-based platform providing the following functions: (i) access and interrogate the EAM data exported from clinical mapping systems; (ii) efficient browsing of EAM data to preview mapping procedures, electrograms (EGMs), and electro-cardiograms (ECGs); (iii) conversion to modeling formats according to the openCARP standard, to be amenable to analysis with standard tools and advanced workflows as used for in silico EAM data. Documentation and training material to facilitate access to this complementary research tool for new users is provided. We describe the technological underpinnings and demonstrate the capabilities of pyCEPS first, and showcase its use in an exemplary modeling application where we use clinical imaging data to build a patient-specific anatomical model. Conclusion:With pyCEPS we offer an open-source framework for accessing EAM data, and converting these to cardiac modeling standard formats. pyCEPS provides the core functionality needed to integrate EAM data in cardiac modeling research. We detail how pyCEPS could be integrated into model calibration workflows facilitating the calibration of a computational model based on EAM data.

Current trends and outlook of 3D printing in vascular surgery

BackgroundThree-dimensional (3D) printing is an additive manufacturing technique capable of the rapid prototyping of objects not feasible by other manufacturing methods. Vascular surgery has welcomed this technology and found it useful in many areas. MethodsThe integration of 3D-printed models in surgical training offers to bridge existing training gaps and increase exposure to complex pathology, while maintaining patient safety, during this time where the surgical education paradigm is shifting. Sterilizable 3D-printed models are being used to aid in the development of physician-modified endografts with excellent results. Rehearsing with patient-specific anatomic models before surgery has demonstrated evidence in improving operator confidence and decreased operative and fluoroscopy times. Research trends have demonstrated that technology such as printed custom implantable devices with tunable chemical and physical properties may be on the horizon. ResultsDespite all of this, the current use of 3D printing in vascular surgery is limited by factors such as materials, time constraints, and initial technical challenges to developing a printing protocol. All of these are areas actively being researched to improve applicability and adaptation of 3D printing. As its use continues to grow, 3D printing may find utility in meeting the global need for safe, timely, and affordable vascular surgical care. ConclusionsThe analysis delves into current uses, challenges, and future visions for this technology, emphasizing its transformative influence in the field of vascular surgery.

Impact of phase-correction of late-gadolinium enhancement images on quantification of scar metrics and in-silico VT-modelling in patients with an ischemic cardiomyopathy

Abstract Background Late gadolinium enhancement (LGE) is used to perform tissue characterization and has become the cornerstone to guide treatment of ventricular tachyarrhythmia (VT). Traditionally, LGE acquisition is reconstructed in two distinct forms: non-phase corrected magnitude (MIR) and phase-corrected inversion recovery (PSIR) images. However, the influence of MIR vs. PSIR on the quantification of scar metrics and the repercussion on estimating myocardial arrhythmogenicity have not been comprehensively explored. Aim This study investigated the influence of PSIR and MIR LGE on the quantification of scar metrics in a randomly selected cohort of patients with ischemic cardiomyopathy who had undergone imaging prior to ICD implantation and had received device therapy during follow-up. In addition, this study assessed how these image variations affect functional estimation of arrhythmogenicity using computational modelling. Methods ADAS 3D LV was used to generate scar maps from 2D PSIR and MIR LGE images in 10 patients. The extent of variation in scar-characteristics was evaluated by quantifying the borderzone (BZ), scar core, and conduction corridors. Electrical simulations were performed on the patient-specific anatomical models using the Virtual Induction and Treatment of Arrhythmias (VITA) framework. VITA was used to assess the electrical vulnerability of potential reentrant channels and provided the number of inducible VTs and their corresponding round-trip-time (RTT), an equivalent of VT cycle-length. Results Scar quantification using PSIR LGE resulted in a significantly larger BZ (22.1±23.7g vs. 6.2±2.7g, p <.001) and scar core (43.5±21.5g vs. 10.5±4g, p =.047). Furthermore, both the absolute number (6.8±4 vs. 3.4±1.5, p = .031) and weight (13±13.1g vs. 1.4±0.8g, p =.018) of conduction corridors were also higher using PSIR. VTs were inducible in 8 PSIR-models and 7 MIR-models. Despite large differences in scar characteristics, VITA metrics were not significantly different between PSIR and MIR derived models. Although, the absolute number of inducible VTs were larger for PSIR (6.2±5.4 vs. 3.4±3.1), non-parametric testing using Wilcoxon signed-rank test did not demonstrate a significant difference (Z = -1.334, p =.139). A comparable, non-significant difference was observed for mean- (117±78 vs. 79±60, p =.257) and max-RTT (181±141 vs. 120±103, p =.294) between PSIR and MIR derived models. Conclusion PSIR resulted in significantly larger BZ, scar core area, and conduction corridors. While the absolute, VITA-derived estimation of myocardial arrhythmogenicity, including inducible VTs and RTT, were higher in the PSIR-based quantification, these differences did not reach statistical significance. These results highlight important differences between two clinically applied image reconstruction techniques for the assessment of arrhythmogenic substrate, emphasizing the need for additional investigation and refinement of scar quantification techniques.

Quality assurance of 3D-printed patient specific anatomical models: a systematic review

BackgroundThe responsible use of 3D-printing in medicine includes a context-based quality assurance. Considerable literature has been published in this field, yet the quality of assessment varies widely. The limited discriminatory power of some assessment methods challenges the comparison of results. The total error for patient specific anatomical models comprises relevant partial errors of the production process: segmentation error (SegE), digital editing error (DEE), printing error (PrE). The present review provides an overview to improve the general understanding of the process specific errors, quantitative analysis, and standardized terminology.MethodsThis review focuses on literature on quality assurance of patient-specific anatomical models in terms of geometric accuracy published before December 4th, 2022 (n = 139). In an attempt to organize the literature, the publications are assigned to comparable categories and the absolute values of the maximum mean deviation (AMMD) per publication are determined therein.ResultsThe three major examined types of original structures are teeth or jaw (n = 52), skull bones without jaw (n = 17) and heart with coronary arteries (n = 16). VPP (vat photopolymerization) is the most frequently employed basic 3D-printing technology (n = 112 experiments). The median values of AMMD (AMMD: The metric AMMD is defined as the largest linear deviation, based on an average value from at least two individual measurements.) are 0.8 mm for the SegE, 0.26 mm for the PrE and 0.825 mm for the total error. No average values are found for the DEE.ConclusionThe total error is not significantly higher than the partial errors which may compensate each other. Consequently SegE, DEE and PrE should be analyzed individually to describe the result quality as their sum according to rules of error propagation. Current methods for quality assurance of the segmentation are often either realistic and accurate or resource efficient. Future research should focus on implementing models for cost effective evaluations with high accuracy and realism. Our system of categorization may be enhancing the understanding of the overall process and a valuable contribution to the structural design and reporting of future experiments. It can be used to educate specialists for risk assessment and process validation within the additive manufacturing industry.Graphical Context of the figures in this review. Center: Fig. 5+ 7; top (blue): Fig. 8; right (green): Fig. 9; bottom (yellow): Fig. 10; left (red): Fig. 11. A version in high resolution can be found online in the supplementary material.

Application of three-dimensional printed biomodels in endoscopic spinal surgery.

Three-dimensional printing (3DP) is increasingly used to individualise surgery and may be an effective tool for representing patient anatomy. Current literature on patient-specific anatomical models (biomodels) for minimally invasive spinal surgery is a limited number of case series and cohort studies. However, studies investigating 3DP in other specialties have reported multiple benefits. This prospective study considered a series of patients (n=33) undergoing elective endoscopic spinal surgery, including combinations of microdiscectomy (n=27), foraminotomy (n=7), and laminectomy (n=3). These surgeries were conducted at vertebral levels ranging from L2/3 to L5/S1. The surgeon then recorded the impact on preoperational planning, intraoperative decision-making and accelerating the learning curve with a qualitative questionnaire. There were benefits to planning in 54.5% of cases (n=18), improved intraoperative decision-making in 60.6% of cases (n=20). These benefits were reported more frequently earlier in the cases, with improvements to learning reported in 60% of the first five cases and not in subsequent cases. The surgeon commented that the biomodels were more useful on. The rates of preoperative and intraoperative benefits are consistent with existing studies, and the early benefit to the learning curve may be suitable for applications to surgical training. Additional research is required to determine the practicality of biomodels and their impact on patient outcomes for endoscopic spinal surgery.

Use of three-dimensional printing technology for supporting the hip reconstruction surgery in paediatric patients

The use of three-dimensional (3D) printed patient-specific anatomical models is nowadays a viable strategy for improving surgical outcome in medicine. In adult surgery, 3D printing technology is commonly studied, but its use in paediatric surgery is still under development. This work presents the implementation of 3D printing technology in Orthopaedic department of the paediatric hospital “Santobono-Pausilipon” in Naples by fabricating 3D printed anatomical models of paediatric patients. The 3D printed models fabricated were used for the training of the surgical team during the preoperative planning and for carrying out a surgical simulation. The anatomical models are designed in compliance with the current European Medical Devices regulation and following the already existing guidelines in literature. The impact of the 3D printed anatomical models used, a total of seven printed anatomical models based on four patients, is then evaluated throughout a questionnaire proposed to the surgical team, composed by eight paediatric orthopaedic surgeons. Surgeons answered to a total of ten questions, six scale-based questions and four free-text questions. Results obtained from the questionnaires highlighted how 3D printed anatomical models can lead to a better understating of the treated pathologies, carrying relevant improvements in both the surgical team training and the surgical outcome.

Assessing views and attitudes toward the use of extended reality and its implications in neurosurgical education: a survey of neurosurgical trainees.

Extended reality (XR) systems, including augmented reality (AR), virtual reality (VR), and mixed reality, have rapidly emerged as new technologies capable of changing the way neurosurgeons prepare for cases. Thus, the authors sought to evaluate the perspectives of neurosurgical trainees on the integration of these technologies into neurosurgical education. A 20-question cross-sectional survey was administered to neurosurgical residents and fellows to evaluate perceptions of the use of XR in neurosurgical training. Respondents evaluated each statement using a modified Likert scale (1-5). One hundred sixteen responses were recorded, with 59.5% of participants completing more than 90% of the questions. Approximately 59% of participants reported having institutional access to XR technologies. The majority of XR users (72%) believed it was effective for simulating surgical situations, compared with only 41% for those who did not have access to XR. Most respondents (61%) agreed that XR could become a standard in neurosurgical education and a cost-effective training tool (60%). Creating patient-specific anatomical XR models was considered relatively easy by 56% of respondents. Those with XR access reported finding it easier to create intraoperative models (58%) than those without access. A significant percentage (79%) agreed on the need for technical skill training outside the operating room (OR), especially among those without XR access (82%). There was general agreement (60%) regarding the specific need for XR. XR was perceived as effectively simulating stress in the OR. Regarding clinical outcomes, 61% believed XR improved efficiency and safety and 48% agreed it enhanced resection margins. Major barriers to XR integration included lack of ample training hours and/or time to use XR amid daily clinical obligations (63%). The data presented in this study indicate that there is broad agreement among neurosurgical trainees that XR holds potential as a training modality in neurosurgical education. Moreover, trainees who have access to XR technologies tend to hold more positive perceptions regarding the benefits of XR in their training. This finding suggests that the availability of XR resources can positively influence trainees' attitudes and beliefs regarding the utility of these technologies in their education and training.

Role of Three-Dimensional Printing in Treatment Planning for Orthognathic Surgery: A Systematic Review.

Three-dimensional (3D) printing refers to a wide range of additive manufacturing processes that enable the construction of structures and models. It has been rapidly adopted for a variety of surgical applications, including the printing of patient-specific anatomical models, implants and prostheses, external fixators and splints, as well as surgical instrumentation and cutting guides. In comparison to traditional methods, 3D-printed models and surgical guides offer a deeper understanding of intricate maxillofacial structures and spatial relationships. This review article examines the utilization of 3D printing in orthognathic surgery, particularly in the context of treatment planning. It discusses how 3D printing has revolutionized this sector by providing enhanced visualization, precise surgical planning, reduction in operating time, and improved patient communication. Various databases, including PubMed, Google Scholar, ScienceDirect, and Medline, were searched with relevant keywords. A total of 410 articles were retrieved, of which 71 were included in this study. This article concludes that the utilization of 3D printing in the treatment planning of orthognathic surgery offers a wide range of advantages, such as increased patient satisfaction and improved functional and aesthetic outcomes.

The Inaugural "Century" of Mixed Reality in Cranial Surgery: Virtual Reality Rehearsal/Augmented Reality Guidance and Its Learning Curve in the First 100-Case, Single-Surgeon Series.

Virtual reality (VR) refers to a computer-generated three-dimensional space in which a surgeon can interact with patient-specific anatomic models for surgical planning. Augmented reality (AR) is the technology that places computer-generated objects, including those made in VR, into the surgeon's visual space. Together, VR and AR are called mixed reality (MxR), and it is gaining importance in neurosurgery. MxR is helpful for selecting and creating templates for an optimal surgical approach and identifying key anatomic landmarks intraoperatively. By reporting our experience with the first 100 consecutive cases planned with VR and executed with AR, our objective is to detail the learning curve and encountered obstacles while adopting the new technology. This series includes the first 100 consecutive complex cranial cases of a single surgeon for which MxR was intended for use. Effectiveness of the VR rehearsal and AR guidance was analyzed for four specific contributions: (1) opening size, (2) precise craniotomy placement, (3) guidance toward anatomic landmarks or target, and (4) antitarget avoidance. Seventeen cases in the study cohort were matched with historical non-MxR cases for comparison of outcome parameters. The cases in which MxR failed were plotted over time to determine the nature of the "learning curve." AR guidance was abandoned in eight operations because of technical problems, but problem-free application of MxR increased between the 44th and 63rd cases. This provides some evidence of proficiency acquisition in between. Comparing the 17 pairs of matched MxR and non-MxR cases, no statistically significant differences exist in the groups regarding blood loss, length of stay nor duration of surgery. Cases where MxR had above-expectation performances are highlighted. MxR is a powerful tool that can help tailor operations to patient-specific anatomy and provide efficient intraoperative guidance without additional time for surgery or hospitalization.

Trends and Challenges in the Development of 3D-Printed Heart Valves and Other Cardiac Implants: A Review of Current Advances.

This article provides a comprehensive review of the current trends and challenges in the development of 3D-printed heart valves and other cardiac implants. By providing personalized solutions and pushing the limits of regenerative medicine, 3D printing technology has revolutionized the field of cardiac healthcare. The use of several organic and synthetic polymers in 3D printing heart valves is explored in this article, with emphasis on both their benefits and drawbacks. In cardiac tissue engineering, stem cells are essential, and their potential to lessen immunological rejection and thrombogenic consequences is highlighted. In the clinical applications section, the article emphasizes the importance of 3D printing in preoperative planning. Surgery results are enhanced when surgeons can visualize and assess the size and placement of implants using patient-specific anatomical models. Customized implants that are designed to match the anatomy of a particular patient reduce the likelihood of complications and enhance postoperative results. The development of physiologically active cardiac implants, made possible by 3D bioprinting, shows promise by eliminating the need for artificial valves. In conclusion, this paper highlights cutting-edge research and the promise of 3D-printed cardiac implants to improve patient outcomes and revolutionize cardiac treatment.

The Role of 3D Printing in Treatment Planning of Spine and Sacral Tumors.

Three-dimensional (3D) printing technology has proven to have many advantages in spine and sacrum surgery. 3D printing allows the manufacturing of life-size patient-specific anatomic and pathologic models to improve preoperative understanding of patient anatomy and pathology. Additionally, virtual surgical planning using medical computer-aided design software has enabled surgeons to create patient-specific surgical plans and simulate procedures in a virtual environment. This has resulted in reduced operative times, decreased complications, and improved patient outcomes. Combined with new surgical techniques, 3D-printed custom medical devices and instruments using titanium and biocompatible resins and polyamides have allowed innovative reconstructions.

Recent Advancements in 3-D Printing in Medical Applications

The field of three-dimensional (3D) printing has witnessed significant advancements in recent years, and its potential for revolutionizing medical applications is rapidly emerging. This review aims to provide an overview of the current state and scope of 3D printing in the medical field. The review begins by highlighting the various 3D printing technologies currently employed in healthcare settings, including stereolithography, selective laser sintering, fused deposition modeling, and inkjet printing. Each technology's advantages and limitations are discussed, shedding light on their suitability for different medical applications. Next, the review delves into the diverse range of medical applications where 3D printing has shown promise. These applications include the fabrication of patient-specific anatomical models for preoperative planning, surgical guides and tools, customized implants and prosthetics, tissue engineering scaffolds, and drug delivery systems. The potential benefits of using 3D printing in these areas, such as enhanced surgical accuracy, improved patient outcomes, reduced surgery time, and personalized medicine, are explored. Furthermore, the review addresses the challenges and limitations associated with implementing 3D printing in medical settings. These challenges include regulatory concerns, standardization of processes, material biocompatibility, cost-effectiveness, and scalability. The ongoing efforts to overcome these barriers and the future directions of 3D printing in medicine are also discussed. In conclusion, 3D printing holds immense potential for transforming various aspects of medical practice. While considerable progress has been made, there are still challenges to be addressed before widespread adoption can be achieved. With continued research and development, coupled with regulatory support and collaboration between academia, industry, and healthcare professionals, 3D printing is poised to International Journal of Scientific Research in Engineering and Management (IJSREM) Volume: 07 Issue: 07 | July - 2023 SJIF Rating: 8.176 ISSN: 2582-3930 © 2023, IJSREM | www.ijsrem.com DOI: 10.55041/IJSREM24845 | Page 2 make a substantial impact in the field of medicine, improving patient care and treatment outcomes. Key words: Additive manufacturing (AM); Bio-medical; Fused Deposition Modelling (FDM); Selective Laser Sintering (SLS); Stereolithography (SLA); Digital Light Processing (DLP); Binder Jetting; Material Jetting; Direct Energy Deposition (DED).

Optimization of laser dosimetry based on patient-specific anatomical models for the ablation of pancreatic ductal adenocarcinoma tumor

Laser-induced thermotherapy has shown promising potential for the treatment of unresectable primary pancreatic ductal adenocarcinoma tumors. Nevertheless, heterogeneous tumor environment and complex thermal interaction phenomena that are established under hyperthermic conditions can lead to under/over estimation of laser thermotherapy efficacy. Using numerical modeling, this paper presents an optimized laser setting for Nd:YAG laser delivered by a bare optical fiber (300 µm in diameter) at 1064 nm working in continuous mode within a power range of 2–10 W. For the thermal analysis, patient-specific 3D models were used, consisting of tumors in different portions of the pancreas. The optimized laser power and time for ablating the tumor completely and producing thermal toxic effects on the possible residual tumor cells beyond the tumor margins were found to be 5 W for 550 s, 7 W for 550 s, and 8 W for 550 s for the pancreatic tail, body, and head tumors, respectively. Based on the results, during the laser irradiation at the optimized doses, thermal injury was not evident either in the 15 mm lateral distances from the optical fiber or in the nearby healthy organs. The present computational-based predictions are also in line with the previous ex vivo and in vivo studies, hence, they can assist in the estimation of the therapeutic outcome of laser ablation for pancreatic neoplasms prior to clinical trials.

Cell to whole organ global sensitivity analysis on a four-chamber heart electromechanics model using Gaussian processes emulators.

Cardiac pump function arises from a series of highly orchestrated events across multiple scales. Computational electromechanics can encode these events in physics-constrained models. However, the large number of parameters in these models has made the systematic study of the link between cellular, tissue, and organ scale parameters to whole heart physiology challenging. A patient-specific anatomical heart model, or digital twin, was created. Cellular ionic dynamics and contraction were simulated with the Courtemanche-Land and the ToR-ORd-Land models for the atria and the ventricles, respectively. Whole heart contraction was coupled with the circulatory system, simulated with CircAdapt, while accounting for the effect of the pericardium on cardiac motion. The four-chamber electromechanics framework resulted in 117 parameters of interest. The model was broken into five hierarchical sub-models: tissue electrophysiology, ToR-ORd-Land model, Courtemanche-Land model, passive mechanics and CircAdapt. For each sub-model, we trained Gaussian processes emulators (GPEs) that were then used to perform a global sensitivity analysis (GSA) to retain parameters explaining 90% of the total sensitivity for subsequent analysis. We identified 45 out of 117 parameters that were important for whole heart function. We performed a GSA over these 45 parameters and identified the systemic and pulmonary peripheral resistance as being critical parameters for a wide range of volumetric and hemodynamic cardiac indexes across all four chambers. We have shown that GPEs provide a robust method for mapping between cellular properties and clinical measurements. This could be applied to identify parameters that can be calibrated in patient-specific models or digital twins, and to link cellular function to clinical indexes.

Higher Computed Tomography (CT) Scan Resolution Improves Accuracy of Patient-specific Mandibular Models When Compared to Cadaveric Gold Standard

3D-printed patient-specific anatomical models are becoming an increasingly popular tool for planning reconstructive surgeries to treat oral cancer. Currently there is a lack of information regarding model accuracy, and how the resolution of the computed tomography (CT) scan affects the accuracy of the final model. The primary objective of this study was to determine the CT z-axis resolution necessary in creating a patient specific mandibular model with clinically acceptable accuracy for global bony reconstruction. This study also sought to evaluate the effect of the digital sculpting and 3D printing process on model accuracy. This was a cross-sectional study using cadaveric heads obtained from the Ohio State University Body Donation Program. The first independent variable is CT scan slice thickness of either 0.675, 1.25, 3.00, or 5.00mm. The second independent variable is the three produced models for analysis (unsculpted, digitally sculpted, 3D printed). The degree of accuracy of a model as defined by the root mean square (RMS) value, a measure of a model's discrepancy from its respective cadaveric anatomy. All models were digitally compared to their cadaveric bony anatomy using a metrology surface scan of the dissected mandible. The RMS value of each comparison evaluates the level of discrepancy. One-way ANOVA tests (P<.05) were used to determine statistically significant differences between CT scan resolutions. Two-way ANOVA tests (P<.05) were used to determine statistically significant differences between groups. CT scans acquired for 8 formalin-fixed cadaver heads were processed and analyzed. The RMS for digitally sculpted models decreased as slice thickness decreased, confirming that higher resolution CT scans resulted in statistically more accurate model production when compared to the cadaveric gold standard. Furthermore, digitally sculpted models were significantly more accurate than unsculpted models (P<.05) at each slice thickness. Our study demonstrated that CT scans with slice thicknesses of 3.00mm or smaller created statistically significantly more accurate models than models created from slice thicknesses of 5.00mm. The digital sculpting process statistically significantly increased the accuracy of models and no loss of accuracy through the 3D printing process was observed.

A state-of-the-art guide about the effects of sterilization processes on 3D-printed materials for surgical planning and medical applications: A comparative study.

Surgeons use different medical devices in the surgery, such as patient-specific anatomical models, cutting and positioning guides, or implants. These devices must be sterilized before being used in the operation room. There are many sterilization processes available, with autoclave, hydrogen peroxide, and ethylene oxide being the most common in hospital settings. Each method has both advantages and disadvantages in terms of mechanics, chemical interaction, and post-treatment accuracy. The aim of the present study is to evaluate the dimensional and mechanical effect of the most commonly used sterilization techniques available in clinical settings, i.e., Autoclave 121, Autoclave 134, and hydrogen peroxide (HPO), on 11 of the most used 3D-printed materials fabricated using additive manufacturing technologies. The results showed that the temperature (depending on the sterilization method) and the exposure time to that temperature influence not only the mechanical behavior but also the original dimensioning planned on the 3D model. Therefore, HPO is a better overall option for most of the materials evaluated. Finally, based on the results of the study, a recommendation guide on sterilization methods per material, technology, and clinical application is presented.