MR-compatible Pump for Validation of PC-MRI Flows

The measurement of flows in MRI is also called phase-contrast MRI (PC-MRI) and enables non-contact flow measurement of blood or cerebrospinal fluid. Conclusions about pathological changes can help to diagnose diseases (e.g. normal pressure hydrocephalus). Although measurements have been performed on both healthy subjects and patients for many years and significant changes have been seen, the PC-MRI method has been criticized for its accuracy. In order to be able to quantify the accuracy of the measurement method, an MR-compatible pump was developed at the department. The challenges were mainly the pump drive and the material selection. The drive was realized by a pneumatically driven pump using only rapid prototyping. The pump drives a cam plate via a defined gear ratio. The cam disk is connected to a movable element on a linear guiding, which converts the rotational motion into a translational motion. This element pushes and pulls the fixed bellows, producing a defined flow in a tube section, which can be measured in PC-MRI. The entire setup is made of polymers so that no artifacts are produced in the MRI. In addition, the speed can be adjusted by the air pressure and the flow can be modified by the cam geometry.