MR meeting takes sentimental journey to exciting new future

The 2007 International Society for Magnetic Resonance in Medicine meeting looked backed at past accomplishments and forward to innovations that will define future MRI practice. The meeting, jointly sponsored with the European Society for Magnetic Resonance in Medicine and Biology, was held in Berlin May 19 to 25, two months after the death of Paul Lauterbur, Ph.D., a key figure in the invention of MRI.

Attendees learned that Lauterbur, who was awarded the Nobel Prize in Physiology or Medicine in 2003 for his discovery, helped organize the Society for Magnetic Resonance in Medicine and served as its first president. The SMRM was one of two professional societies that merged to become the International Society for Magnetic Resonance in Medicine in 1993.

This year was also the 25th anniversary of MRI's introduction as a diagnostic tool in clinical oncology. Dr. Hedvig Hricak, chair of radiology at Memorial Sloan-Kettering Cancer Center, devoted her presentation of the annual Lauterbur Oration to MRI's achievements over the past quarter century.

Hricak did not dwell on nostalgia, though MRI has fueled medical imaging progress practically since Lauterbur's discoveries in 1971. The modality helped eliminate the need for exploratory surgery. It introduced noninvasive anatomic and functional methods for diagnosing the presence and location of disease and provided precise tools for treatment selection and monitoring.

"Nothing is permanent except change, and with MRI, we can master that change and move to the next level," she said.

For guiding treatment planning, MRI's impact has been greatest in the brain, Hricak said. MR fiber tractography, for example, reveals relationships between eloquent tissue that can guide or even contraindicate surgery, as in this figure, where tumor severely distorts the tracts of nearby fibers.

Because of MRI's ability to noninvasively measure and volumetrically map temperature, it is an excellent guide for focused ultrasound therapy and cryosurgery. As new chemotherapies are introduced, MRI will be used increasingly as a surrogate marker for early tumor response, she said.

The best way to predict the future is to invent it, Hricak said. She challenged colleagues to focus on imaging advancements to eliminate the threat of breast cancer as a fatal disease.

The future of MRI also rides on increasing field strength, she said. The clinical community is making the transition from 1.5T to 3T as the standard for high-field performance. The higher signal-to-noise ratio possible from that change will improve the modality's anatomic resolution and the sensitivity of MR spectroscopy to molecular metabolites.

Standardized diffusion, perfusion, and other quantitative MRI methods are needed to minimized interobserver variability. They must become easier to perform to overcome radiologist resistance to their adoption, she said.

Progress will also come on the shoulders of hybrid scanners that simultaneously exploit the benefits of PET and MRI. Two key benefits from this combination will arise. PET/MRI improves on PET/CT by reducing radiation exposure. And PET/MRI offers a daunting number of anatomic, functional, and metabolic combinations to interrogate disease.

The 2007 joint ISMRM/ESMRMB meeting was memorable for its record-breaking achievements. Attendance records were broken with more than 6600 radiologists, technologists, students, and vendor representatives onsite. The 985 oral presentations, 1933 traditional posters, and 929 electronic posters also established new records.

MRI's premier scientific assembly has grown so large that multiple perspectives are needed to identify the highlights. Here is how several respected sources viewed the proceedings:

NEPHROGENIC SYSTEMIC FIBROSIS

"The emerging problems around contrast-enhanced MR studies and NSF were debated among experts and the audience in a dedicated panel discussion. Officials from the European Agency for the Evaluation of Medicinal Products participated from London via two-way teleconference. The session served as the start for an ISMRM working group on NSF, chaired by former society president Dr. Walter Kucharczyk. It will define guidelines and recommendations for the use of gadolinium-containing contrast application in the future." Dr. Georg Bongartz, ISMRM/ESMRMB program committee chair.

PROSTATE CANCER

"Many studies used 3T. Once the manufacturers translate their 1.5T clinical packages for 3T, most people will begin using 3T MR for prostate cancer.

"Several sessions were devoted to hyperpolarized carbon-13 spectroscopy. That technology is moving along. Mark Albers of our group showed with a transgenic mouse model a grade-dependent increase in hyperpolarized lactate. Primary tumors had more hyperpolarized lactate than at baseline, and late-stage and metastatic tumors had high levels of lactate as well. It looks like it may be a great marker for prostate cancer and may translate nicely into the clinic." Dr. John Kurhanewitz, professor of radiology and pharmaceutical chemistry, University of California, San Francisco.

CELL TRACKING

"The highlight of the meeting was the lively, at times belligerent, debate at the molecular and cellular imaging study group meeting. This year's theme was what is better: MPIO (bigger particles) or SPIO (smaller particles), and positive or negative contrast? The clear winner was SPIO, mainly due to its clinical translation value. The vote for the best contrast was divided, perhaps because the positive contrast approach has not been widely tested yet for its advantages.

"New developments included fluorinated 'multimodal' agents by the Johns Hopkins group, with cells being simultaneously detectable by MRI and x-ray, and the use of ferritin cage, iron oxide nanoparticles as alternative SPIO-based agents." Dr. Jeff W.M. Bulte, director of the cellular imaging section, Institute for Cell Engineering, Johns Hopkins University School of Medicine.

CARDIAC VESSEL WALL

"Papers suggested new sequences for better flow suppression, novel contrast mechanisms, the potential use of contrast-enhanced MRI, and noncontrast-enhanced imaging. Molecular imaging targeting specific components of plaque could be very meaningful for detecting plaque instability." Dr. Zahi A. Fayad, professor of radiology, Mount Sinai Medical Center.

BODY MRI

"In body MR, there has been a lot of interest in perfusion-weighted imaging, particularly for quantitative measures of cancer, assessing responses to therapy and metastatic potential. While a lot of work has been done in the brain with susceptibility imaging, the T1-weighted imaging methods used in the body have only just started to receive rigorous attention.

"It is not clear yet what the real role of diffusion will be or how it will fare when compared with contrast-enhanced imaging, but many groups are clearly starting to explore it." Dr. Vivian Lee, ISMRM president-elect.

INTERVENTIONAL MRI

"One unifying theme was the trend toward higher field strength for interventional guidance and therapy monitoring, along with a renewed emphasis on the treatment of cancer and other mass lesions. Monday afternoon's thermal therapy scientific session was heavily weighted toward MR monitoring of high-intensity focused ultrasound, along with excellent papers documenting further progress in thermal monitoring of laser, radiofrequency, and cryoablation techniques.

"Tuesday morning's plenary session was devoted to intervention, with a lecture in which I highlighted clinical applications in routine patient care. Michael Bock, Ph.D., presented technical advances in the field, and Dr. Clare Tempany presented future clinical directions. A lively oral poster discussion session on Wednesday afternoon included the use of interventional MRI in the prostate and the integration of robotics into the interventional procedure." Dr. Jonathan Lewin, radiologist-in-chief, Johns Hopkins University Medical Center.

RF TECHNOLOGY/BIOMARKERS

"Major technical advances were described around multichannel transmit RF technology. This will be most helpful in the short term for dealing with B1 inhomogeneity in the brain and body at 7T but should also benefit specific absorption rate issues at 3T and 7T and allow some intriguing new applications that use spatially tailored RF pulses.

"MR mixed with other technologies-optical, ultrasound, and of course PET-was also a highlight. MR/PET promises to be particularly interesting in diseases like Alzheimer's and cancer given how powerful each of the two modalities are in their own domains, because the power of MR is typically complementary to PET.

"Some of the most interesting research continues to be around biomarkers. Interest in using MRI in drug development and therapeutic monitoring is higher than ever, with some interesting results using diffusion MRI to identify very early changes in brain tumor responses." Dr. A. Gregory Sorensen, director, Center for Biomarkers in Imaging, Massachusetts General Hospital.

NONCONTRAST MRA

"I suspect that the recent findings (relating to NSF) will renew interest in MRA methods that do not require the injection of a contrast bolus, such as time-of-flight and phase-contrast. Sessions on cardiovascular flow quantification and vessel imaging above the arch showed impressive results and visualizations in the evaluation of complex flow patterns and understanding of disease, especially the work of Dr. Michael Markl's group at the University Hospital in Freiburg, Germany.

"I also enjoyed several presentations on overcoming challenges for cardiac imaging at 3T. I applaud the efforts of numerous research groups in investigating acceleration techniques such as kt-BLAST, compressed Sensing, and HYPR processing in order to improve achievable frame rates or reduce scan times to feasible breath-hold lengths or patient comfort." Oliver Wieben, Ph.D., associate scientist, department of medical physics, University of Wisconsin-Madison.

James Brice is senior editor for Diagnostic Imaging.