Q&A with Filip Szczepankiewicz and Markus Nilsson

In today’s interview, we highlight the latest paper by first author Filip Szczepankiewicz, from Brigham and Women’s Hospital in Boston, and last author Markus Nilsson, from Lund University in Sweden. Their paper is titled “Maxwell-compensated design of asymmetric gradient waveforms for tensor-valued diffusion encoding”.

For those who would like to get a quick overview of our discussion, below is an annotation of the interview. Clicking on the timestamp will take you to the exact video location where the topic is discussed.
0:00 Intro: We catch up with the authors about their backgrounds, and Filip answers once and for all the question that has surely popped into the mind of many colleagues: how to pronounce his last name.

3:34 Filip gives his take on concomitant gradients. He likens them to the “Baba Yaga” of MRI: something that’s always in the background and can cause trouble.

6:05 Audioslides: All gradients create concomitant gradients, and for asymmetric gradient designs (i.e. before and after the 180 degree pulse) they may not cancel. The authors developed a design scheme that can correct for this effect, and shared an open source framework for optimization and analysis of concomitant fields.

13:14 Asked about how easy it would be to implement this correction, Filip clarifies that we shouldn’t see this primarily as a correction. It could be one, but you would need to know your experiment extremely well. Instead, he sees this more as a way to estimate the magnitude of the error to help better design your waveforms.

15:23 The effects of uncorrected concomitant gradients increase with gradient strength. The authors are currently looking into gradient nonlinearity corrections.

17:11 For multiband imaging, this technique solves the problem better than alternative corrections like shifting the isocenter.<br />

18:43 After releasing their code online, the authors have been assisting new users to use it in their own projects.

20:40 Markus has been making a conscious effort to build an open-source code base not just in his own lab, but in collaboration with other labs. As a reviewer, he would also like to see more people sharing their code to have more transparency about their work.

22:03 Nikola hints at some upcoming changes regarding MRM Highlights beginning in 2020.