Hendrik de Leeuw1, Peter R. Seevinck1, Chris J.G. Bakker1
1Image Sciences Institute, Utrecht, Netherlands
Accurate localization of field perturbing objects e.g. needles, catheters and brachytherapy seeds, is difficult with MRI since induced signal voids are non-specific and distorted. Center-out Radial Sampling with Off-Resonance reception (co-RASOR) has been shown to locate perturbers accurately with high positive contrast, by selecting the optimum from many off-resonance acquisitions. Herein the efficiency and flexibility is significantly increased by making multiple off-resonance reconstructions from one on-resonance acquisition and automatically extracting the optimal frequency offset. The equivalence in accuracy of co-RASOR and CT is demonstrated by a phantom experiment, its flexibility with an arbitrarily oriented biopsy needle in inhomogeneous porcine tissue.