Prepolarized magnetic resonance imaging around metal orthopedic implants

作者：Ross Venook, Nathaniel I. Matter, Meena Ramachandran, Sharon E. Ungersma, Garry E. Gold, Nicholas J. Giori, Albert Macovski, Greig Scott, Steven Conolly · 发表于：Magnetic Resonance in Medicine · 年份：2006 · DOI：10.1002/mrm.20927 · 被引用次数：81 · 研究领域：Advanced MRI Techniques and Applications、Atomic and Subatomic Physics Research、Electrical and Bioimpedance Tomography

A prepolarized MRI (PMRI) scanner was used to image near metal implants in agar gel phantoms and in in vivo human wrists. Comparison images were made on 1.5- and 0.5-T conventional whole-body systems. The PMRI experiments were performed in a smaller bore system tailored to extremity imaging with a prepolarization magnetic field of 0.4 T and a readout magnetic field of 27-54 mT (1.1-2.2 MHz). Scan parameters were chosen with equal readout gradient strength over a given field of view and matrix size to allow unbiased evaluation of the benefits of lower readout frequency. Results exhibit substantial reduction in metal susceptibility artifacts under PMRI versus conventional scanners. A new artifact quantification technique is also presented, and phantom results confirm that susceptibility artifacts improve as expected with decreasing readout magnetic field using PMRI. This proof-of-concept study demonstrates that prepolarized techniques have the potential to provide diagnostic cross-sectional images for postoperative evaluation of patients with metal implants.