Fresh concepts could speed up MRI

Novel concepts and approaches are essential to speed up MRI examinations. Furthermore, pushing speed limits does not just mean doing the same things quicker - new application areas must also be found.

These are the opinions of Prof. Jürgen Hennig, cochair and scientific director of the department of radiology and medical physics at Freiburg University Hospital in Germany. Henning gave the Wilhelm Conrad Röntgen Honorary Lecture on Saturday.

Users are benefiting from a growing number of tools for fast imaging, he said. In addition to improved sequences, such as echo planar imaging and RARE (rapid acquisition with relaxation enhancement), there are stronger and faster gradients. Parallel imaging, which is already well established in 2D imaging, is also playing a role.

Speed in MR is a compromise among spatial resolution, signal-to-noise ratio, volume coverage, image quality, and image contrast. Pushing the speed limit is linked to improving SNR by using more and better coils and higher fields plus implementing other measures like hyperpolarization, Hennig said.

State-of-the-art methods allow users to optimize imaging efficiency within predefined time constraints. Users should select the available time window and define the best approach, not just select the imaging protocol and hope for the best, he said.

Major increases in imaging speed in 3D examinations and/or in repetitive examinations such as cine imaging are evolving and will lead to further progress as coil design and reconstruction algorithms develop, according to Hennig.

In the bigger picture of optimizing patient care, users must remember that reliable diagnosis leading to correct and curative therapy is the top priority, he said. It is important to stress that more imaging reduces time to recovery.

Delegates particularly enjoyed Hennig's humorous slide that showed a photo of himself in a red sports car being pursued by an evil-looking "k-space police" vehicle. The officer asked Hennig if he knew he was traveling at n³ times the Nyquist speed limit.