Magnetic Resonance Imaging at 3.0 Tesla: Challenges and Advantages in Clinical Neurological Imaging

Abstract

MR imaging at very high field (3.0 T) is a significant new clinical tool in the modern neuroradiological armamentarium. In this report, we summarize our 40-month experience in performing clinical neuroradiological examinations at 3.0 T and review the relevant technical issues. We report on these issues and, where appropriate, their solutions. Issues examined include: increased SNR, larger chemical shifts, additional problems associated with installation of these scanners, challenges in designing and obtaining appropriate clinical imaging coils, greater acoustic noise, increased power deposition, changes in relaxation rates and susceptibility effects, and issues surrounding the safety and compatibility of implanted devices. Some of the these technical factors are advantageous (eg, increased signal-to-noise ratio), some are detrimental (eg, installation, coil design and development, acoustic noise, power deposition, device compatibility, and safety), and a few have both benefits and disadvantages (eg, changes in relaxation, chemical shift, and susceptibility). Fortunately solutions have been developed or are currently under development, by us and by others, for nearly all of these challenges. A short series of 1.5 T and 3.0 T patient images are also presented to illustrate the potential diagnostic benefits of scanning at higher field strengths. In summary, by paying appropriate attention to the discussed technical issues, high-quality neuro-imaging of patients is possible at 3.0 T.

Intramyocellular lipid quantification: comparison between 3.0- and 1.5-T 1H-MRS

“…Changing the operating field from 1.5T to 3.0T theoretically results in a twofold gain in SNR, since magnetization increases with the square of the field strength while noise increases linearly [19]. However, prior studies examining changes in brain SNR from 1.5T to 3.0T have demonstrated increases in the range of 30-60% for T2-weighted fast-spin echo imaging [19], 28% for short-echo single-voxel stimulated echo acquisition mode (STEAM) spectroscopy [11], 23% for single-voxel PRESS spectroscopy [10], and 23-46% for long-echo 3D multivoxel spectroscopy [20].…”

Proton MR spectroscopy of the brain at 3 T: an update

“…The advantages of shorter examination times for patients, radiologists, technicians and hospital administrators are obvious. Higher spatial resolution improves the matching of metabolic and anatomical information, enhancing the clinical value of 1 H-MRS [11].…”

“…In the last decade, with the approval of the US Food and Drug Administration for clinical use, MR systems at 3 T are proliferating, particularly at research centers [11]. With respect to the well-established MR technique at 1.5 T, switching to a higher field brings several advantages, such as an increased signal-to-noise ratio, with consequent enhanced spatial and temporal resolutions, and better spectral resolution, but also many limitations, such as installation issues, higher acoustic noise, device compatibility, system inhomogeneity, eddy current artifacts, misregistration errors, J-modulation anomalies, magnetic field instability and safety restrictions.…”

“…With respect to the well-established MR technique at 1.5 T, switching to a higher field brings several advantages, such as an increased signal-to-noise ratio, with consequent enhanced spatial and temporal resolutions, and better spectral resolution, but also many limitations, such as installation issues, higher acoustic noise, device compatibility, system inhomogeneity, eddy current artifacts, misregistration errors, J-modulation anomalies, magnetic field instability and safety restrictions. Some technical characteristics, such as changes in relaxation times, chemical shift and susceptibility, can have both benefits and disadvantages [11][12][13][14][15]. These limitations necessitating changes in technical devices and acquisition strategies have led to a debate about the usefulness of higher field strength in clinical settings [14][15][16][17][18][19][20].…”

Visualization of Ovarian Tumors using 3T MR Imaging: Diagnostic Effectiveness and Difficulties

“…Theoretically, the signal-to-noise ratio (SNR) obtained by 3T MR imaging should be double that obtained at 1.5T, and the gain in SNR could be used to reduce scanning time or reduce the voxel size for high resolution images to less than one mm. 1,2 Numerous reports have documented the advantages of the 3T MR imaging system over the 1.5T system for morphological evaluation, functional imaging, and spectroscopy of the brain. 1,[3][4][5][6][7] However, in practice, the SNR increases but does not double, probably as a result of signal inhomogeneity or some artifacts, 1,2 and improved image quality at 3T is countered by drawbacks that include greater susceptibility eŠect, increased speciˆc absorption rate (SAR), and radiofrequency (RF)ˆeld inhomogeneity.…”