Since their introduction in the late 1970’s MRI systems have evolved inexorably towards higher field strengths due to the greater spin polarization, and ultimately image signal-to-noise ratio, that higher fields allow. Commensurate with the increasing field strength was the need to overcome the many technical challenges associated primarily with the higher Larmor frequencies involved, from SAR-related safety considerations and imaging sequence modifications to new radiofrequency coil design concepts. This push to higher fields led to the recent arrival of 7 Tesla MRI systems into the clinical domain. The benefits and challenges of imaging at 7 Tesla will be reviewed, both from a technical/physics perspective and that of developing clinical applications of this technology. Future prospects for this technology will be reviewed.
At the same time, advances in MR technology and imaging techniques are facilitating renewed interest in imaging at lower field strengths. The benefits that pertain to imaging at low field will be reviewed, from 0.55 Tesla all the way down into the low milliTesla regime. New applications of a 0.55 Tesla MRI system equipped with contemporary hardware and software for cardiac imaging, lung imaging and MRI-guided cardiac interventions will be discussed, together with the capabilities of this system for routine diagnostic imaging. A high performance MRI system which operates at 6.5 mT will be described, highlighting the technical innovations which facilitate diagnostic impact. The use of modern image acquisition and reconstruction methods that can be used to maintain SNR and image quality at lower fields will also be discussed.
Learning Outcomes
1. Understand the underlying physics concepts describing the benefits of MR imaging at 7 T
2. Be familiar with the technical challenges of 7 T MRI and techniques to mitigate image artifacts
3. Demonstrate a knowledge of the safety aspects of 7T MRI
4. Understand the breath and limitations of current clinical applications of 7 T MRI
5. Apply knowledge of how modern image acquisition and reconstruction methods can be used to maintain SNR and image quality at lower fields
6. Understand the benefits of imaging at lower magnetic fields
7. Understand the opportunities and limitations of potential clinical applications for low field MRI
Not Applicable / None Entered.
Not Applicable / None Entered.