Three patent applications were published in July, that are all related to what is called concomitant gradient correction. This refers to magnetic field vector components that are unwanted but occurring as a byproduct of the desired magnetic fields in MRI. The three patents each address measurement, hardware-based correction, and software correction. The problem of concomitant field first came to me in early 2000s when I was a graduate student working on microTesla MRI with superconducting sensors. That work was reported here in a JMR article: https://pubmed.ncbi.nlm.nih.gov/19664947/. At that time the issue was too weak a main magnetic field; now the problem is due to too strong a gradient field. Different regime, but the same physics.
Seungkyun's Magnetic Resonance Life Blog
Friday, October 18, 2024
Wednesday, September 11, 2024
Three papers of summer of 2024
I was silent for 3 months! In those summer months, 3 papers of mine came out, in Journal of Applied Physics, IEEE Transactions on Magnetics, and Magnetic Resonance Imaging. They report studies related to, and motivated by, MRI gradient coils. The three papers, respectively, provide a first systematic mathematical formulation of magneto-mechanical coupling, derive a versatile, surface eddy current equation, and describe a practical method to reduce acoustic noise in high-performance MRI. They all center around solving critical engineering problems in high-field, high-gradient MRI, in order to make strong magnetic fields more accessible and exploitable for advanced brain imaging. Apart from the subject matter, a not-so-coincidental feature that is common to all three papers is that they have a non-sectioned, single-paragraph abstract! They are also in journals where authors don't have to pay to publish.
Saturday, June 8, 2024
Head-only then and now
Saturday, April 20, 2024
Digital posters for ISMRM 2024
Tuesday, April 16, 2024
DIANA questions, raised scientifically
A first scientific counterargument against DIANA was published recently in an open-access journal: A different interpretation of the DIANA fMRI signal | Science Advances. The three main points are the following: (1) The authors did reproduce the original MRI data and therefore the original report by Toi et al. in Science is likely true on observed facts. (2) On the other hand, the authors could explain their own observations better without invoking neuronal response, but rather based on instrumental artifacts and coincidental circumstances. (3) Regarding membrane potential-induced T2 change, the authors believe that the originally reported in-vitro T2 change is rather caused by cell swelling than membrane potential. The authors did leave several questions unanswered that need to be answered in order to reconcile their assertion with the large amount of experimental data reported in Toi et al.
It is notable that the authors humbly titled their paper as "A different interpretation of DIANA fMRI" and showed reservation of judgment and desire to be constructive. The paper ends with a respectable remark, "Although the goal of probing neural activity with millisecond temporal resolution using fMRI remains unmet, we hope that the contribution of Toi et al. will inspire further efforts to achieve this ambitious and worthy objective."
The questions raised by this paper are certainly serious and substantial. But they were brought up in a way to allow professional debate and objective mutual verification. I hope this development, along with the growing body of positive data from Prof. Park's team, will soon bring clarity to this tantalizing DIANA puzzle.