Tagged MR imaging in a deforming phantom: photographic validation.

Abstract

To validate cine magnetic resonance (MR) image tagging measurements of a deforming object by means of a precise photographic method. A piece of silicone rubber that acted as a phantom was stretched in a cyclical fashion inside a plastic clamp driven by a respirator pump. Deformation as a function of time was measured with a rapid gradient-echo cine tagging sequence and with sequential stroboscopic photographs. Deformations from 1.0 to 1.2 (0% to 20% stretch) in the readout direction were measured over a 7-cm region of the phantom, which had a maximum standard error of +/- 0.001 with photography and a maximum standard error of +/- 0.003 with MR imaging. The deformation versus time values measured with MR imaging had a standard error of 0.002 about a straight line fit to the photographic deformation versus time data. These results demonstrate that the MR imaging deformation estimates were accurate and precise. The validated tagging method can now be used to evaluate MR imaging motion estimation techniques.