A cardiac phantom and pulsatile flow pump for magnetic resonance imaging studies.

Abstract

Fast scan magnetic resonance imaging (MRI) acquisitions are a rapid noninvasive means of evaluating the cardiovascular system. Because the appearance of flowing blood is highly variable, the interpretation of these images is sometimes difficult. A nonferromagnetic phantom that could generate lifelike pulsatile flow and also simulate the motions of the beating heart would facilitate image interpretation. This paper describes an MRI-compatible cardiovascular phantom that mimics the motions of the heart and also creates physiologic pulsatile flow. The phantom consists of a ventricle and an air pump that drives it. The pump is connected to the ventricle with seven meters of air hose so that the pump (which has ferromagnetic parts) can be placed outside the magnet room. The ventricle is placed in an airtight Plexiglas cylinder and the pump alternately pressurizes and depressurizes the cylinder, driving fluid in and out of the ventricle. The motions of the ventricular wall simulate the motions of the heart, and the pulsatile flow generated is of physiologic velocities and volumes. This phantom also can be used with other methods of evaluating cardiovascular function, such as MUGAS, angiography, and Doppler, allowing correlation between MRI and other modalities. Finally, the phantom can be used to study almost any aspect of cardiovascular function from pulsatile flow velocity to ventricular studies (ejection fractions, cardiac output, wall motion) and even studies of stenotic or regurgitant valves.