Low Cost Fabrication of PVA Based Personalized Vascular Phantoms for in Vitro Haemodynamic Studies: Three Applications

Vascular phantoms mimicking human vessels are commonly used to perform in vitro haemodynamic studies for a number of bioengineering applications, such as medical device testing, clinical simulators and medical imaging research. Simplified geometries are useful to perform parametric studies, but accurate representations of the complexity of the in vivo system are essential in several applications as personalised features have been found to play a crucial role in the management and treatment of many vascular pathologies. Despite numerous studies employing vascular phantoms produced through different manufacturing techniques, an economically viable technique, able to generate large complex patient-specific vascular anatomies, still needs to be identified. In this work, a manufacturing framework to create personalised and complex phantoms with easily accessible and affordable materials is presented. In particular, 3D printing with polyvinyl alcohol (PVA) is employed to create the mould, and lost core casting is performed to create the physical model. The applicability and flexibility of the proposed fabrication protocol is demonstrated through three phantom case studies - an idealised aortic arch, a patient-specific aortic arch, and a patient-specific aortic dissection model. The phantoms were successfully manufactured in a rigid silicone, a compliant silicone and a rigid epoxy resin, respectively; using two different 3D printers and two casting techniques, without the need of specialist equipment

Patient-Specific Aortic Phantom with Tuneable Compliance

Validation of computational models using in vitro phantoms is a non-trivial task, especially in the replication of the mechanical properties of the vessel walls which varies with age and pathophysiological state. In this paper, we present a novel aortic phantom reconstructed from patient-specific data with variable wall compliance that can be tuned without recreating the phantom. The 3D geometry of an aortic arch was retrieved from a Computed Tomography Angiography scan. A rubber-like silicone phantom was manufactured and connected to a compliance chamber in order to tune its compliance. A lumped resistance was also coupled with the system. The compliance of the aortic arch model was validated using the Young's modulus and characterised further with respect to clinically relevant indicators. The silicone model demonstrates that compliance can be finely tuned with this system under pulsatile flow conditions. The phantom replicated values of compliance in the physiological range. Both, the pressure curves and the asymmetrical behaviour of the expansion, are in agreement with the literature. This novel design approach allows obtaining for the first time a phantom with tuneable compliance. Vascular phantoms designed and developed with the methodology proposed in this paper have high potential to be used in diverse conditions. Applications include training of physicians, pre-operative trials for complex interventions, testing of medical devices for cardiovascular diseases and comparative MRI-based computational studies