Comparison Between Numerical and MRI Data of Ascending Aorta Hemodynamics in a Circulatory Mock Loop

Abstract

The possibility to obtain in-vitro evaluation of hemodynamic flows and pressures is of capital importance in understanding cardiovascular pathologies and validating new devices. The in-vitro approach brings different advantage including the possibility to evaluate fluid dynamic parameters non invasively and to support in-silico simulations. In this study, a patient specific mock circulatory loop is developed to reproduce the fluid dynamic physiological conditions. A full sequence of 4D flow MRI is used as a benchmark for extraction of anatomical and functional patient specific data. The anatomical MRI data were used to realize a 3D printed rigid phantom of the complete aortic branch. The phantom is realized with a single inlet at aortic root level and 4 outlets corresponding to the supra-aortic arteries and the descending aorta. The model is then inserted inside a custom mock-circulatory loop, composed by an active component and a series of passive components to model the systemic resistances and compliances at each branch. The active component is responsible for the imposition of the flow rate waveform at the inlet section and it is constituted by a custom speed-controlled piston pump. The inlet flow rate is set by automatically interpolating the patient specific aortic flow from MRI data. The functional MRI data were used to validate the flow condition at each outlet branch. In the present work the preliminary results of the circulatory mock loop are compared with MRI data and with the results of numerical simulations carried out for the considered aorta geometry and inlet flow rate by using Simvascular. The in-vitro flow profiles are compared with the in-vivo and the numerical ones in the descending aorta and at each outlet branch. The reproduction of the flow rate is successful, with errors at systolic peaks of 5 cc/s and 1.66 cc/s for the supra-aortic and the descending aorta level respectively. Also the physiological pressure range is rather well reproduced in the in-vitro experiments.