Standing-wave artefact in high-field MRI systems

Magnetic resonance imaging (MRI) scanners with 3.0 Tesla (T) were introduced in clinical settings in the early 2000s to improve diagnostic performances of previous MRI generations. By switching from 1.5T to 3.0T MRI scanners, there is a double increase in the number of hydrogen protons, and so there is a double increase in the signal-to-noise ratio and better spatial and temporal resolutions¹. Though unexpected, several technical challenges have been discovered after the transition, including an increase in specific absorption rates (SAR), chemical shifts and T1 relaxation times². At scanners with higher magnetic fields, the inhomogeneity of the secondary magnetic field (B1) causes an unpredictable and challenging imaging artefact, which is called the “standing-waves effect”. As a result of this artefact, signals in the region of interest (ROI) are void, which compromises the diagnostic performance of this modality. However, various reduction strategies...