Neuroradiology
Ultra-high-field Clinical Magnetic Resonance Imaging— Challenges and Excitement
William TC Yuh, MD, MSEE,1 Gregory A Christoforidis, MD,2 Wieslaw L Nowinski, DSc, PhD,5 Nina A Mayr, MD,3 Michael V Knopp, MD, PhD1 Christina L Sammet, PhD,4 and Steffen Sammet, MD, PhD1,2
1. Department of Radiology, Ohio State University; 2. Department of Radiology, University of Chicago; 3. Department of Radiation Oncology, Ohio State University; 4. Department of Radiology, Northwestern University; 5. Biomedical Imaging Laboratory, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research
Abstract
With the rapid advance of magnetic resonance imaging (MRI) technologies, many of the critical problems experienced with ultra-high-field (UHF) MRI have either been resolved or improved so that various disease entities and pathophysiologies can be investigated in clinical settings. Based on the preliminary clinical data, new ‘excitation waves’ induced by UHF MRI have triggered ‘multiecho resonances’ throughout the medical and scientific community, as well as among manufacturers, owing to the potential of this technology in research and patient care. However, there are also criticisms of UHF MRI regarding its biophysiologic limitations, unsolved technical and safety issues, and cost-effectiveness. While the debate continues over whether UHF MRI is a useful ‘new tool for the child,’ technical improvements continue to be made and the clinical applications of the technology continue to expand. This article discusses the challenges, opportunities, preliminary clinical results, and limitations of UHF MRI for clinical applications in humans.
Keywords Ultra-high-field magnetic resonance imaging, 7 or 8 Tesla MRI, whole-body human clinical magnetic resonance imaging, clinical application
Disclosure: This study was supported by the National Cancer Institute (NCI grant no. R21CA/NS92846-01A1) and the Wright Center of Innovation in Biomedical Imaging. Received: July 19, 2010 Accepted: September 9, 2010 Citation: US Radiology, 2011;3:16–22 Correspondence: William TC Yuh, MD, MSEE, Radiology Department, Ohio State University Medical Center, Suite 489, 395 W 12th Ave, Columbus, OH 43210. E:
yuh.6@osu.edu
In this article, the term ultra-high-field magnetic resonance imaging (UHF MRI) is used to describe MRI studies performed with a whole-body human MR scanner using a magnetic field strength (B0) equal to or greater than 7 Tesla (T), whereas the term conventional MRI pertains to those scanners with field strengths equal to or lower than 3 T. Most of the discussion in this article will focus on the clinical application of 7- and 8 T MRI. Within the field of MRI, overall imaging quality, capabilities, and potential, as well as technical and biophysiological challenges, increase with greater field strength of MR scanners.1–14
Ultimately, the practical questions that need to be answered are the optimal field strength for clinically relevant imaging and the cost-effectiveness of the technique. With the rapid advance of MRI technologies, many of the problems experienced with UHF MRI have either been resolved or improved to enable new capabilities that allow the investigation of various clinical disease entities and pathophysiologies. Meanwhile, there are still significant challenges remaining owing to the inherent biophysiologic properties and unresolved technical problems that limit the potential of UHF MRI.
Since their introduction to clinical applications in the 1980s, whole-body human MR scanners with various magnetic field strengths up to 3 T have made significant contributions to patient care and have
16
become an essential part of the daily clinical management of various pathophysiologies, particularly in the central nervous system (CNS)3,14–24 and musculoskeletal system.25,26
With the implementation of advanced
As spatial and temporal resolution have continued to improve and the field strength of commercially available whole-body MRI scanners has continued to increase, functional imaging has become another exciting area for patient care and research.
fast imaging techniques, MRI has gained a broader role in other organ systems, including abdominal, pulmonary, and cardiac imaging, over the past decade.27–30
Until recently, many doubted the utility and cost-effectiveness of 3 T human MRI systems, largely because of the expected technical challenges, safety issues, and high costs. Fortunately, many of the technical problems were resolved without disproportionally increasing the cost. The 3 T human scanners have now become a realistic state-of-the-art imaging modality for clinical utilization. With their increased field strength, 3 T whole-body MR systems provide superior anatomic and functional imaging quality and improved capability compared with established 1.5 T systems. Enthusiasm among scientists, physicians, and manufacturers for even higher-field-strength clinical MRI systems continues to grow with the success and increased acceptance of the 3 T clinical systems. The popular philosophy ‘the bigger, the better’ or ‘the higher, the better’
© TOUCH BRIEFINGS 2011
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68