Project description:We aim to facilitate phantom-based (ground truth) evaluation of dynamic, quantitative myocardial perfusion imaging (MPI) applications. Current MPI phantoms are static representations or lack clinical hard- and software evaluation capabilities. This proof-of-concept study demonstrates the design, realisation and testing of a dedicated cardiac flow phantom. The 3D printed phantom mimics flow through a left ventricular cavity (LVC) and three myocardial segments. In the accompanying fluid circuit, tap water is pumped through the LVC and thereafter partially directed to the segments using adjustable resistances. Regulation hereof mimics perfusion deficit, whereby flow sensors serve as reference standard. Seven phantom measurements were performed while varying injected activity of 99mTc-tetrofosmin (330-550 MBq), cardiac output (1.5-3.0 L/min) and myocardial segmental flows (50-150 mL/min). Image data from dynamic single photon emission computed tomography was analysed with clinical software. Derived time activity curves were reproducible, showing logical trends regarding selected input variables. A promising correlation was found between software computed myocardial flows and its reference ([Formula: see text]= - 0.98; p = 0.003). This proof-of-concept paper demonstrates we have successfully measured first-pass LV flow and myocardial perfusion in SPECT-MPI using a novel, dedicated, myocardial perfusion phantom. This proof-of-concept study focuses on the development of a novel, dedicated myocardial perfusion phantom, ultimately aiming to contribute to the evaluation of quantitative myocardial perfusion imaging applications.
Project description:Autologous fat grafting is the gold standard for treatment in patients with soft-tissue defects. However, the technique has a major limitation of unpredictable fat resorption due to insufficient blood supply in the initial phase after transplantation. To overcome this problem, we investigated the capability of a medical-grade poly L-lactide-co-poly ε-caprolactone (PLCL) scaffold to support adipose tissue and vascular regeneration. Deploying FDM 3D-printing, we produced a bioresorbable porous scaffold with interconnected pore networks to facilitate nutrient and oxygen diffusion. The compressive modulus of printed scaffold mimicked the mechanical properties of native adipose tissue. In vitro assays demonstrated that PLCL scaffolds or their degradation products supported differentiation of preadipocytes into viable mature adipocytes under appropriate induction. Interestingly, the chorioallantoic membrane assay revealed vascular invasion inside the porous scaffold, which represented a guiding structure for ingrowing blood vessels. Then, lipoaspirate-seeded scaffolds were transplanted subcutaneously into the dorsal region of immunocompetent rats (n = 16) for 1 or 2 months. The volume of adipose tissue was maintained inside the scaffold over time. Histomorphometric evaluation discovered small- and normal-sized perilipin+ adipocytes (no hypertrophy) classically organized into lobular structures inside the scaffold. Adipose tissue was surrounded by discrete layers of fibrous connective tissue associated with CD68+ macrophage patches around the scaffold filaments. Adipocyte viability, assessed via TUNEL staining, was sustained by the presence of a high number of CD31-positive vessels inside the scaffold, confirming the CAM results. Overall, our study provides proof that 3D-printed PLCL scaffolds can be used to improve fat graft volume preservation and vascularization, paving the way for new therapeutic options for soft-tissue defects.
Project description:Simulation is integral to the development and maintenance of micro- surgical skills. Several simulation models have been described ranging from bench- top to live animal models. High fidelity models are often burdened by cost and ethical issues limiting widespread implementation. This study aims to determine the feasibility of a microsurgical training platform using the Konjac noodle model.MethodsA prospective cohort study was conducted at our institution. A progressive microsurgical training curriculum was developed. A bespoke three-dimensional printed training platform was produced to enable residents to record training and assessment tasks. Microsurgical skills were blindly assessed before and after completing the training program using the University of Western Ontario Microsurgical Skills Assessment instrument.ResultsPlastic surgery residents at various stages of training were recruited (n = 10). A significant improvement in vessel preparation from a pre-training median of 3 (IQR 2 -4) versus a post-training of 4 (IQR 3 -5, P = 0.0035) and suturing with a pre-training median of 3 (IQR 2 -4) versus a post-training of 4 (IQR 3 -5, P = 0.0047) domains of the University of Western Ontario Microsurgical Skills Assessment score was demonstrated after completion of the training program. There was a significant improvement in the global rating score (3 ± 1 versus 5 ± 1, P = 0.0045). Participants felt more confident performing a microsurgical anastomosis following the training program.ConclusionThe use of the Konjac noodle model and video-based assessment using a three-dimensional printed model is an effective teaching tool that improves resident's microsurgical skills.
Project description:An interbody fusion cage is crucial in spine fusion procedures, serving to restore physiological vertebral alignment and reestablish spinal stability. However, conventional fusion cages often face challenges related to insufficient osteointegration and the requirement for substantial bone grafting, which may result in incomplete fusion and prolonged recovery periods. In this study, we harnessed the osteointegration advantages of tantalum (Ta), in conjunction with advanced 3D printing technology, to develop a novel non-window-type Ta cage. The mechanical and biological characteristics of the cage were comprehensively evaluated through mechanical testing, in vitro cellular assays, and in vivo sheep anterior cervical discectomy and fusion models. The results indicated that the 3D-printed porous tantalum (3D-pTa) cage, with mechanical properties analogous to those of trabecular bone, exhibited superior bone ingrowth and osseointegration performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. Moreover, we performed a pilot clinical trial to assess the performance of non-window-type 3D-pTa cages in single-level posterior lumbar interbody fusion. The results demonstrated that 3D-pTa achieved favorable clinical outcomes up to the 12-month follow-up period. These results highlight the significant clinical potential of the 3D-pTa cage for spinal fusion applications.
Project description:Application of in-shoe multi-segment foot kinematic analyses currently faces a number of challenges, including: (i) the difficulty to apply regular markers onto the skin, (ii) the necessity for an adequate shoe which fits various foot morphologies and (iii) the need for adequate repeatability throughout a repeated measure condition. The aim of this study therefore was to design novel magnet based 3D printed markers for repeated in-shoe measurements while using accordingly adapted modified shoes for a specific multi-segment foot model.Multi-segment foot kinematics of ten participants were recorded and kinematics of hindfoot, midfoot and forefoot were calculated. Dynamic trials were conducted to check for intra and inter-session repeatability when combining novel markers and modified shoes in a repeated measures design. Intraclass correlation coefficients were calculated to determine reliability.Both repeatability and reliability were proven to be good to excellent with maximum joint angle deviations of 1.11° for intra-session variability and 1.29° for same-day inter-session variability respectively and ICC values of >0.91.The novel markers can be reliably used in future research settings using in-shoe multi-segment foot kinematic analyses with multiple shod conditions.
Project description:Studying seismic wave propagation through complex media is crucial to numerous aspects of geophysics and engineering including seismic hazard assessment. In particular, small-scale structure such as sedimentary basins and their edges can have significant effects on high-frequency earthquake ground motion, which is the main cause for the damage to buildings and infrastructure. However, such structural effects are poorly understood due to limitations in numerical and analytical methods. To overcome this challenge, for the first time, we utilize the 3D printing technique to build a scaled-down physical representation of geological structure and perform lab-scale seismic experiments on it. Specifically, a physical model based on the Los Angeles Basin is printed and used as synthetic medium to propagate ultrasonic waves, to mimic seismic wave propagation from local earthquakes. Our results show clear body and surface waves recorded at expected time and locations, as well as waves that are scattered from the basin edges. We find that high-frequency energies are significantly reduced at the basin, which is at odds with the conventional view of basins as ground motion amplifiers. This novel waveform modeling approach with 3D printed Earth models is largely automated and provides an effective means to tackle geophysical problems of significance.
Project description:Central line placement, cricothyroidotomy, and lumbar epidural placement are common procedures for which there are simulators to help trainees learn the procedures. However, a model or a simulator for thoracic epidurals is not commonly used by anesthesia training programs to help teach the procedure. This brief technical report aims to share the design and fabrication process of a low-cost and do-it-yourself (DIY) 3D-printed thoracic spine model. Ten expert anesthesiology attendings and fifteen novice anesthesiology residents practiced with the model and were subsequently surveyed to assess their attitudes towards its fidelity and usefulness as a teaching tool. Responses were recorded with a Likert scale and found to be positive for both groups. Design files and an assembly manual were developed and made public through an open-source website.
Project description:Functional heterogeneity is a skeletal muscle's ability to generate diverse force vectors through localised motor unit (MU) recruitment. Existing 3D macroscopic continuum-mechanical finite element (FE) muscle models neglect MU anatomy and recruit muscle volume simultaneously, making them unsuitable for studying functional heterogeneity. Here, we develop a method to incorporate MU anatomy and information in 3D models. Virtual fibres in the muscle are grouped into MUs via a novel "virtual innervation" technique, which can control the units' size, shape, position, and overlap. The discrete MU anatomy is then mapped to the FE mesh via statistical averaging, resulting in a volumetric MU distribution. Mesh dependency is investigated using a 2D idealised model and revealed that the amount of MU overlap is inversely proportional to mesh dependency. Simultaneous recruitment of a MU's volume implies that action potentials (AP) propagate instantaneously. A 3D idealised model is used to verify this assumption, revealing that neglecting AP propagation results in a slightly less-steady force, advanced in time by approximately 20 ms, at the tendons. Lastly, the method is applied to a 3D, anatomically realistic model of the masticatory system to demonstrate the functional heterogeneity of masseter muscles in producing bite force. We found that the MU anatomy significantly affected bite force direction compared to bite force magnitude. MU position was much more efficacious in bringing about bite force changes than MU overlap. These results highlight the relevance of MU anatomy to muscle function and joint force, particularly for muscles with complex neuromuscular architecture.
Project description:PurposeTo investigate the potential reconstruction of complex maxillofacial defects using computer-aided design 3D-printed polymeric scaffolds by defining the production process, simulating the surgical procedure, and explore the feasibility and reproducibility of the whole algorithm.MethodsThis a preclinical study to investigate feasibility, reproducibility and efficacy of the reconstruction algorithm proposed. It encompassed 3 phases: (1) scaffold production (CAD and 3D-printing in polylactic acid); (2) surgical simulation on cadaver heads (navigation-guided osteotomies and scaffold fixation); (3) assessment of reconstruction (bone and occlusal morphological conformance, symmetry, and mechanical stress tests).ResultsSix cadaver heads were dissected. Six types of defects (3 mandibular and 3 maxillary) with different degree of complexity were tested. In all case the reconstruction algorithm could be successfully completed. Bone morphological conformance was optimal while the occlusal one was slightly higher. Mechanical stress tests were good (mean value, 318.6 and 286.4 N for maxillary and mandibular defects, respectively).ConclusionsOur reconstructive algorithm was feasible and reproducible in a preclinical setting. Functional and aesthetic outcomes were satisfactory independently of the complexity of the defect.