A rotating phantom for the study of flow effects in MR imaging.

A common type of phantom used for the study of flow effects in MR imaging is the tube phantom, where a liquid passes through a set of tubes placed in the main magnetic field of an MR scanner. Among the disadvantages with this type of phantom are that a distribution of velocities is present in each tube, and that quantifications of flow effects using tube phantoms may be very time-consuming. In this work, we describe the design and the properties of a rotating wheel flow phantom used for quantification of the effects of flow through the imaging plane as well as in the imaging plane. The proposed phantom is constructed as a rotating gel-filled wheel, surrounded by static volumes filled with the same gel, and the evaluation of the information from rotating and static parts is made with a specially designed computer program. The phantom can be used as a plug flow phantom covering simultaneously an interchangeable velocity interval, which at present has the range -52 mm/s, +52 mm/s. It is shown that the phantom gives adequate information on the dependence of pixel content on first-order motion in MR modulus and phase images. Among the fields of application are rapid calibration of MR imaging units for flow determination using phase information, as well as testing of pulse sequence characteristics and verification of theoretical predictions concerning the flow dependence in MR images.