Back to the basics on 2D line scan and DIANA

Prof. Jang-Yeon Park and his graduate student Jae-Youn Keum at SKKU published a two-author paper (link) in MRM on the theoretical analysis and experimental mitigation of image artifacts caused by so-called pseudo-steady-state (PSS) in gradient-echo based 2D line scan. The PSS has plagued Direct Imaging of Neuronal Activity since its inception through insidious artifacts that mimicked neuronal excitation signals. The new publication addresses the problem head-on, and can help control or eliminate such artifacts to make the line scan method more reliable. Kudos to the team of Prof. Park, whose incessant pursuit of the holy grail of MR neuroimaging continues to stimulate the field and refine methodology.

7th installation of MAGNUS in June

Somewhere in Texas, another research-dedicated 3T MAGNUS scanner was installed in June. This is the 7th in the world, and 5th in the USA. At least one more will come this year, continuing the trend of growing adoption of high-performance gradient systems for brain research. 

Helium-free MRI on the rise, and GE's compact 7T scanner

Helium-free MRI is on the rise, spurred by high helium cost as well as general awareness of resource conservation needs around the globe. GE had a very early technical lead on this front, but it is only very recent that it is devoting full efforts to commercialization of the technology for mainstream MRI scanners. In this week's ISMRM meeting, "Freelium" 1.5 T scanners were announced (again) as products-to-be of GE HealthCare. For research, a low-helium highlight was GE's Compact 7T scanner, presented by Tom Foo in a scientific oral session, as an Annual Meeting Program Committee-selected talk.

Combining high-field (7T), strong & fast gradients, and compact geometry is technically very difficult for even conventional liquid helium-filled magnets. Doing this on a helium-free system is almost insane because of the difficulty in magnet heating control. Making human 7T compact is therefore a very high-risk proposal.

The world's first such system was announced in the talk with impressive 7T brain images, achieved with minimal tailored hardware or processing for image quality. The technology might meaningfully change the 7T research landscape in the coming decade.

ISMRM annual meeting in two weeks

This year the attendance to the ISMRM annual meeting, at least from the northern Asia-Pacific region, is expected to be low. Many from the US as far as I can tell are not travelling to Cape Town, South Africa. I have two posters to present, but they will instead be covered by two of my colleagues who do travel. The way digital posters are uploaded has been changed (again!), and has received criticism. The word limitation of 750 is unreasonable, and many will simply upload ppt slides as figures, to defeat the limits. In order to make contents visible in small-screen phones, posters are now forced to be partitioned into small pieces, and while they are thus made more fluid and amorphous, it is being done in a rigid and restrictive way. At one point more attention should be paid and efforts be devoted to the picture, not the frame.

[Note added during the Conference week] As feared, many digital posters were very hard to read because many authors just uploaded their ppt slides in small figure spaces, or they did not know what to do with the word limit so the poster contents were badly fragmented and all bullet-ized. Something has to be done here.

Farewell to Dr. John Schenck

John Schenck Obituary--https://www.simplechoicescremation.com/obituaries/john-schenck-md-phd

John was a great mentor and friend to many who worked in the General Electric MRI Laboratory since its inception in the 1980s. As the obituary above describes it well, he was a true pioneer of modern MRI who invented the fingerprint gradient coils, co-invented the birdcage coil, and advocated for patient safety. His comprehensive review of the role of magnetic susceptibility in MRI (https://aapm.onlinelibrary.wiley.com/doi/abs/10.1118/1.597854) is one of the most highly regarded and frequently consulted papers on magnet safety and MRI engineering. He was the early champion of high-performance head-only MRI scanners that are now blooming within and outside the GE company. Having first met him in GE in late 2008, I perhaps only saw a late glimpse of his celebrated career. I was impressed by how he did not look like an authority that he was in the profession; being genuinely nice and approachable, considerate and sensitive, he did not impose himself to push, intercept or hijack conversations as many people in his status (e.g. certain society gold medalist) might do. I was particularly enamored by his phenomenal memory and engaging story-telling when it came to lunch time (and cake club!) gossips and small talks. I wrote a grant proposal with him in 2015, which, unfortunately, did not succeed with NIH. I nevertheless pushed for the research, on habenular imaging, when I was in Korea, and published the results in 2020 (https://doi.org/10.1038/s41598-020-75733-y) with John. After I came back to GE, John had retired but I published a belated paper on the general theory of fingerprint coil design, with John as the second and only coauthor. When it was published in Journal of Applied Physics in 2023, I wondered if this may be his last appearance in research publication. From a quick search this unfortunately appears to be the case. Thank you John for all you did and all you were! I was honored to cross paths with you!

Wisconsin in March

 

The picture above is from a dinner gathering with two Korean families during a business trip to Waukesha, Wisconsin. The future of the magnetic resonance imaging technologies that actually matter to the patients is in the hands of these hard-working and selfless engineers!

University of Iowa in February

Carver Biomedical Research Building of University of Iowa houses the world's first MAGNUS scanner installed in a non-military academic research site. It also has the latest GE Signa 7T human scanner. The investigational Signa MAGNUS 3T scanner recently got an upgrade & repair, and the 7T scanner now has a fully functional parallel transmit capability. This building must be where some of the early 7T brain images were produced, which I obtained from somebody in 2017 in order to compare GE and Siemens 7T images. The building in the picture reminds me of the other building in Korea in a parallel universe, with their expensive facilities, shiny walls, and the energy of young graduate students flocking around a cafeteria.  

King's College London published article on Magnus

King's College London published an on-line news article on the newly installed MAGNUS scanner and its many promising applications. Prof. Steve Williams of the Center for Neuroimaging Sciences (not the other way as in Korea) appeared in a video, along with Dr. Flavio Dell'Acqua, to explain how the scanner is poised to open new fronts in human neuroimaging research.

High (gradient) performance neuroimaging conference in London

This was the 4th annual meeting on high-performance brain MRI, held in King's College London on Dec 10th and 11th. The first meeting in 2022, at GE Research Center in Niskayuna, NY, was mainly for MAGNUS users but the scope is now expanded to all scanners and all applications. This year's speaker lineup was quite impressive, reflecting large interest from the brain imaging community, and also the concentration of top-notch researchers in UK and Europe. Early internet media posts are found here and here. The official program can be found in https://lnkd.in/gWqkMnKK. 

MAGNUS gradient coil gaining ground

An important milestone was reached in October in high-performance human head MRI. The first installation of the MAGNUS 3T research scanners outside the US happened at two places almost at the same time -- in King's College London, UK, and in West China Hospital in China. The scanner is the world's most powerful human neuroimaging machine on the path for commercialization. Now there are a total of 6 research MAGNUS systems in the world, and more are promised to come in 2026. I have so far been at all the installation sites except for in China.

Congratulations, John!

In 1962, in the old Cavendish Lab in Cambridge, UK, Brian Josephson discovered the Josephson effect and was honored by the 1973 Nobel Prize in Physics, shared with Ivar Giaever of GE Global Research (and a 3rd person, Leo Esaki). John Clarke, who went to Cambridge after Josephson, picked up the discovery and greatly advanced the effect's scientific understanding and applications. One of which was,  so it happened, to the detection of magnetic field signals in NMR in the early 2000's. That's when I learned, as his PhD student, the prominent medical imaging modality of MRI. Last week, John was announced to be one of the three physicists to share the 2025 Physics Nobel Prize, and to anyone who knows him, this is a proper, well-made decision. Not only for his scholarly achievements, but for the humble, curious, and example-setting leadership that he has displayed as a teacher, researcher, and a true academic over the decades. We need more people like him in today's world and today's academia.

Retraction to rebound: DIANA paper

Much controversy has emerged since the first appearance of the DIANA paper in the popular literature. Due to the high status of the journal and the high stakes of the claims, a flurry of activities followed to replicate the results which turned out to be elusive. Now, in a nod to the first scientific rebuttal of the paper (Phi Van 2024, A different interpretation of the DIANA fMRI signal), Prof. J.-Y. Park put out a pre-print discussing possibility of contamination of the DIANA signal by artifacts in spoiled gradient-echo imaging. The team, now with a new, rising graduate student (J.-Y. Keum) in the lead, observed non-biological signals akin to DIANA under certain conditions, and concluded that such conditions were likely present in the original experiments. See: Update on the reproduction and interpretation of DIANA fMRI. Given this revelation, the team decided to retract the paper from the journal Science while investigating the exact role that such artifacts played in the initial results. Does this mean the end of DIANA? Unlikely. First, the original paper triggered massive interest in line scan-based fast fMRI which will likely continue in some form. Second, the sheer amount of positive data on detailed association between the DIANA signal and neuronal activities (Keum 2024, Direct imaging of neural activity reveals neural circuits via spatiotemporal activation mapping) cannot possibly be all coincidental. We may still be chasing the signal mechanism. Practically, at any rate, this development underlined the difficulty of separating out a neuronal signal from non-biological artifacts when the former has a low SNR on the order of 0.1%.

MRI research lab featured in public blog

The MRI research lab in NY is featured in the company's public blog, highlighting the lab's history of innovation and recent neuroimaging emphasis. See here.

In a separate news, the King's College in London, UK has announced the 4th High-Performance Neuroimaging Symposium to be held in December (link). This two-day meeting will prominently feature the Lab's 3T head-only scanner development and applications.

Connecting with former students

 

Former members of the SKKU MRI laboratory had a great time in a get-together dinner meeting during my Korea visit in May. Shown in the picture are (from the right) Byung-Pan Song, who will be married in June 2026; Hyeong-Seop Kim (with V), who is working in the healthcare industry, and Jun-Ho Kim who is cheerfully preparing for life after school. I am also working on a presentation for Kibaek Kim, who was a former undergrad student at GBME and who is now organizing a special seminar for his current school he is graduating from. My best wishes to all!

Much happened in Honolulu too.

I delivered three talks on Monday, Wednesday, and Thursday. The Wednesday talk was as a substitute speaker for Prof. Jang-Yeon Park, on the basics of MRI, in particular on the k-space. The talks are all recorded for later views for the meeting registrants. For example, the educational talk is at https://ismrm2025.blazestreaming.com/sessions/ismrm-2025-w-04 (Starting at 40 min mark).

Thanks to the remote registration option, even on-site attendees can now watch most oral sessions from the hotel room, with the benefit of unobstructed, high-resolution view of all the slides. So if one is not particularly interested in seeing the speaker, nor in asking live questions, this was a handsome option not only for convenience but also for quick hopping among many parallel sessions.

One caveat for my future reference: Uploaded talk slides may have automatic slide advance turned on -- make sure this be turned off. 

On the exhibition floor, Chinese companies are clearly gaining ground, with one company displaying an impressive model of rotating whole-body 1.5 T scanner for multi-orientation scans. Notably, Hyperfine missed the show, presumably for financial reasons. To all who I met in person in Honolulu this week, thank you for your kind greetings, and my best wishes!

Much happened before Honolulu

In a busy, dynamic month, we now have the compact 3T scanner working again in Mayo Clinic, and have obtained the first ever -- in history of MRI -- images out of the low-cryogen human head 7T scanner. The former is significant because of the near-continuous operation of the world's only low-cryogen 3T high-performance head scanner for nearly 10 years. The project was meant to last for about 5 years at the beginning. This feels like a Mars rover outliving its planned operation time. The second, compact 7T images, will be much discussed in the upcoming ISMRM meeting in Honolulu. I wish the scanner were a bit more compact physically, but both compact 3T and 7T systems show the direction of MRI that I think is right for its future. That is, to maintain its unique, non-invasive high-resolution imaging, while reducing the footprint and operation cost in order for better access and new applications. Let there be no peers and don't compete with low resolution imaging devices.

I had travelled to Mayo Clinic for a week last week, to see a good weather there in a very busy schedule. Mayo Clinic is thriving, with many expansion constructions on display on the streets.

11.7T in Korea in superconductor science & technology journal

Well, so it was published, finally, last month (SUST article, Feb 2025). A few facts according to the paper: The magnet warm bore is 70 cm in diameter, the magnet runs in persistent mode and has been stable in the last 2+ years. In comparison with the Iseult magnet in France, passive shielding (requiring massive shielding walls) and persistent mode (as opposed to driven mode) appear to be the main differences in addition to the magnet bore size (90 cm for Iseult). I could not find gradient coil specification, but from my visit to Gachon a few years ago, the coil's small thickness is unlikely to allow windings with high gradient amplitudes. The paper included a 3D gradient-echo image of an ex-vivo monkey brain with 12.8 cm FOV and 0.5 mm isotropic resolution. This shows the imaging system is operational but the authors certainly would want more images to meet the magnet's high expectation. So, congratulations to the team, and let's hope more is coming.

Compact 3T service visit to Mayo Clinic

February 2025 marks the 9th anniversary of the delivery of Compact 3T scanner to Mayo Clinic. This year, the week of February 17th was a frigid one, not best for air travel, but a service visit to Rochester, Minnesota was made to replace and renew the magnet's cooling system. Thanks to the hard work of the GE HealthCare colleagues and help from the Mayo Clinic support team, the week's task was completed in time. The work will continue until the end of March, with more service visits to ramp the magnet and calibrate the scanner. Hopefully the refreshed 3T system, still the world's only high-performance compact 3T MRI scanner for humans, will serve the research community for many years to come. 

ISMRM 2025 Abstract Announcement

In my counting, 35 x 151 + 23 = 5308 abstracts are accepted, of which 851 (16%) are oral, and 549 are power pitches. Two submissions of mine were both accepted as an oral presentation, which is not a common event based on the probability (0.16^2 = 2.6%). In addition, Lydia's implanted lead heating work, from Mayo Clinic and where I am the second author, was also accepted as an oral. So apparently you don't have to do low-field or machine learning to get invited to speak in the conference. Now whether I will actually fly to the conference and present in person is another question. I wish remote presentation option was still available after the pandemic. 

Duke university visit

Early this month, an informal research meeting was held at Prof. Allen Song's laboratory at Duke University in North Carolina. Three people from GE Healthcare met with Allen, Prof. Dean Darnell, and a graduate student Devon Overson, to talk about MRI systems engineering to realize wireless receiver coils. This was a second visit in about two years. In 2022, when we were still wearing masks (picture on the left), we had a meeting on the "iPRES" coil, an RF receiver coil that doubles as a multi-channel shim array. The meeting this month, as before, was very productive. The Duke team has worked on wireless signal transmission for peripheral devices control for a number of years. It remains to be seen whether wire-free, battery-powered MRI RF coil can be realized without sacrificing the sensitivity to replace the traditional signal reception architecture.