Evaluation of a Desktop 3D Printed Rigid Refractive-Indexed-Matched Flow Phantom for PIV Measurements on Cerebral Aneurysms

W H Ho,I J Tshimanga,M C Jermy,M N Ngoepe,P H Geoghegan

doi:10.1007/s13239-019-00444-z

Abstract

PurposeFabrication of a suitable flow model or phantom is critical to the study of biomedical fluid dynamics using optical flow visualization and measurement methods. The main difficulties arise from the optical properties of the model material, accuracy of the geometry and ease of fabrication.MethodsConventionally an investment casting method has been used, but recently advancements in additive manufacturing techniques such as 3D printing have allowed the flow model to be printed directly with minimal post-processing steps. This study presents results of an investigation into the feasibility of fabrication of such models suitable for particle image velocimetry (PIV) using a common 3D printing Stereolithography process and photopolymer resin.ResultsAn idealised geometry of a cerebral aneurysm was printed to demonstrate its applicability for PIV experimentation. The material was shown to have a refractive index of 1.51, which can be refractive matched with a mixture of de-ionised water with ammonium thiocyanate (NH4SCN). The images were of a quality that after applying common PIV pre-processing techniques and a PIV cross-correlation algorithm, the results produced were consistent within the aneurysm when compared to previous studies.ConclusionsThis study presents an alternative low-cost option for 3D printing of a flow phantom suitable for flow visualization simulations. The use of 3D printed flow phantoms reduces the complexity, time and effort required compared to conventional investment casting methods by removing the necessity of a multi-part process required with investment casting techniques.

Highlights

An aneurysm is a balloon-like bulge that forms on a blood vessel as a result of weakened vessel wall layers
We investigate the direct printing of flow phantoms from a less expensive material (FLGPCLXX resin from Formlabs), printed with the SLA technique on a desktop Form 2 printer
These images provide an indication of the ‘‘quality’’ that can be achieved with this printed flow phantom

Summary

Introduction

An aneurysm is a balloon-like bulge that forms on a blood vessel as a result of weakened vessel wall layers. The most dangerous aneurysms are found in the Circle of Willis and on the abdominal aorta. The main challenge is that when rupture occurs, there is subsequent morbidity or mortality. Cerebral aneurysms can be treated by surgical or endovascular techniques, such as coils, flow diverters and stents. One of the main challenges relating to treatment is that advances in medical imaging technology have led to an increase in accidental sighting of un-ruptured aneurysms during routine scans for other conditions.[39,42,46]. Given the patient-specific nature of the disease, clinicians are presented with a dilemma as the decision to treat an aneurysm, which would have remained asymptomatic exposes the individual to iatrogenic risk. The decision not to treat could later prove fatal should the aneurysm rupture

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Conclusion