Prof. Daehyun Yoon is one of our newest faculty in Radiology and Biomedical Imaging, and presented on one of his major areas of expertise - MRI Techniques for Artifact Suppression Near Metal. Daehyun previously worked closely with Brian Hargreaves at Stanford, who has been a pioneer of these methods in the last decade.

Fortunately, now all major MRI vendors off some reasonable solutions for imaging near metal implants, and these are based on some form of multi-spectral imaging (MSI). This techinque corrects for both in-plane and through-plane artifacts that arise from the large shifts in the magnetic field ($B_0$) at the interface of metal and tissue.

The tradeoff between imaging speed and spatial resolution remains a challenge for these techniques, as they require additional time compared to conventional sequences. Prof. Yoon showed that compressed sensing is particularly appealing to accelerate these methods due to lots of sparse and redundant signal content.

Achieving quantitative imaging and additional contrast is another challenge, but there were good examples of T2, T1, and ADC mapping attempting to address these challenges.

Low/mid-field MRI systems are quite appealing for patients with implants, as the magnetic field shifts are proportionally reduced as well. Both Prof. Yoon and Prof. Michael Hoff are pursuing this for the 0.55 T Free.MAX system. Daehyun is enthusiastic about using UTE MRI sequences at this field strength as well, and brought up what are to me some clear advantages of high excitation bandwidths as well as spectral encoding and ability for multi-frequency reconstructions for the non-Cartesian k-space trajectories.

Thanks Daehyun for the presentation, and I will be excited to see what you can accomplish in improveing MRI near metal!

Check out more info on Prof. Yoon: https://profiles.ucsf.edu/daehyun.yoon