Tagged MR imaging in a deforming phantom: Photographic validation

PURPOSE: To validate cine magnetic resonance (MR) image tagging measurements of a deforming object by means of a precise photographic method. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: The validated tagging method can now be used to evaluate MR imaging motion estimation techniques.