Suitability analysis of different phantom fluids for MR image artifact measurements with a 7 T MR system

摘要

With the recent clinical application of 7 Tesla MRI in brain and joint imaging, evaluation of MR artifacts of medical implants in high field MR environments gains importance~1. The testing procedure for artifacts requires a phantom containing a liquid, which provides homogeneous signal intensity over the whole phantom. The aim of this investigation was to compare four different phantom materials in terms of their suitability for artifact size testing in 7 T MR Systems. Subjects and Methods: Measurements were performed with a 7Twholebody MRI research system (MAGNETOM 7T, Siemens Healthcare, Germany) in combination with a cross-vendor established and clinically used 1-channel transmit/32-channel receive radiofrequency (RF) head coil (Nova Medical, Wilmington, MA). Phantom materials were a coppersulfate- solution (CuSO4) according to ASTM F21191, a sodium chloride solution (NaCl), rapeseed oil and Polyvinylpyrrolidon (PVP), filled into a polyethylene phantom. Signal uniformity U was calculated according to IEC 624642. A titanium rod (length: 100 mm, diameter: 3.1 mm) was inserted perpendicular to the static magnetic field direction in the phantom. According to ASTM F2119, spin (SE) and gradient echo (GRE) images with transversal slice orientation and phase-encoding direction in both anterior-posterior (AP) and right-left (RL) direction were acquired.