Patient-Specific Aortic Phantom With Tunable Compliance

Abstract

Validation of computational models using in vitro phantoms is a nontrivial 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 three-dimensional (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 characterized 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 behavior of the expansion, are in agreement with the literature. This novel design approach allows obtaining for the first time a phantom with tunable 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 (CVDs), and comparative Magnetic-resonance-imaging (MRI)-based computational studies.

On the Impact of Vessel Wall Stiffness on Quantitative Flow Dynamics in a Synthetic Model of the Thoracic Aorta

“…-and under-damping in the system. Other studies with comparable flow circuit setups showed similar oscillating waveform shapes 21,30,31 . Additional engineering efforts to mitigate this phenomenon may benefit analyses of pressure and flow waveform shapes in multiple vessel geometries and/or under varying boundary conditions.…”

“…Previous work with advanced MRI-compatible flow circuit setups reported similar increased (i.e. >50 mmHg) pulse pressures 21,30,31 . We note that two main factors determine successful pressure tuning: (1) P sys or P MAP can easily be elevated by increasing flow resistance distal to the capacitors for which the pulse pressure remains constant; (2) pulse pressure is governed by the available capacitance, i.e.…”

Low-Cost Fabrication of Polyvinyl Alcohol-Based Personalized Vascular Phantoms for In Vitro Hemodynamic Studies: Three Applications

“…More details about the mechanical characteristics of this phantom and its patient-specific features are described in Ref. [28]. Equally, good qualitative similarity was observed between the geometrical features of phantom 3 CT-scan and the original clinical images (e.g., TL, FL and intimal flap shape, entry-tear dimension and location).…”

Surgical Robotics: Towards Measurable Patient Benefits and Widespread Adoption

“…As shown in Fig. 1 Notable examples are in the field of soft robotics, with new materials (electroactive polymers [28], metamaterials [29] and hydrogels [30]), new structures (steerable needles [31], continuum robots [32], granular jamming [33], [34]), new surgical phantoms [35], [36], and new sensors and sensing schemes (Fibre-Bragg-Grating-based shape sensing [37], bioimpedance tomography [38], fibre-based Optical Coherence Tomography [39], Optical Doppler Flowmetry [40]), and miniaturization, a field that is still in its infancy, but that holds significant promise for the future of patient-specific, non-invasive medicine. As an example, research teams at the Hamlyn Center (Imperial College), supported by the EPSRC's Microengineering Facility for Robotics, are developing a new class of tethered and untethered microscale (grippers [41], micro-tweezers [42], microbots [43]) and nanoscale [44] robots that enable autonomous and remote manipulation of cells and drugs.…”