Motion Phantom Development for MRI

Abstract

The development of magnetic resonance imaging (MRI) has enabled health care professionals to non-invasively visualize subjects' soft tissue for medical diagnosis. Since it's conception, artifacts due to patients' movement have shown themselves to be an issue and an assortment of tools and methods have been developed to help mitigate the effect of motion on MRI but such mitigation methods are generally only applicable on a case by case basis depending on the specific type of motion. As such, additional research is required to develop novel methods and a standardized method of testing, validating, and ultimately comparing mitigation strategies.

This work provides a design to develop a motion stage as well as build instructions for the Martinos head phantom which moves in four degrees of freedom (linear translation in the plane parallel to the floor, a head shaking "no" motion, and a head nodding "yes" motion) independently of one another to limited success. Only the translation in direction (into and out of the bore hole, along the z-axis) worked as expected, while the translation perpendicular to it (x-axis) did not. The total range of motion that head phantom was capable of turning in the head shaking/"no" motion was approximately 19 degrees, though the torque required is on the higher end (on the order of 0.06 N*m) and the position of the rotational actuator needs some reexamination. The head nodding/"yes" mechanism is more promising, allowing for a tilt downwards of 1 degrees and upwards of 2 degrees, but requires actuators capable of exerting 6N of force or more.