High Field MRI: What Are the Special Safety Risks at Higher Fields?

Introduction In the last 10 years the use of MR-scanners with a magnetic field stronger than 3 Tesla (“Ultra-high field MRI”, ie. UHF-MRI, defined as 7 9.4 Tesla in this presentation) has increased sharply, mainly driven by the fact that the three main manufacturers decided to develop 7Tesla MRI scanners for research purposes. More recently, also human 9.4 Tesla research MRI scanners are offered commercially. Over the last ten years, important improvements in hardware and imaging sequences at 7Tesla have led to a quality of fMRI, anatomical neuroimaging, cerebral angiography and spectroscopy clearly surpassing the quality routinely obtained at 3Tesla. This improved performance has resulted in the use of UHF-MRI not only in normal, young volunteers but also for clinical research in patients. When using UHF-MRI scanners in patient populations the amount of subjects having implants or a history of surgery increases sharply, resulting in a more urgent need of safety testing of common implants as well as a strong local implementation of safety procedures. In this presentation, the safety aspects of UHF-MRI will be discussed, both regarding normal volunteers, patients and workers.