Safety Considerations of 7-T MRI in Clinical Practice

Hoff, Michael N.; McKinney, Alexander M.; Shellock, Frank G.; Rassner, Ulrich; Gilk, Tobias; Watson, Robert E.; Greenberg, Todd D.; Froelich, Jerry W.; Kanal, Emanuel

doi:10.1148/radiol.2019182742

Cited by 63 publications

(81 citation statements)

References 71 publications

(76 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…When MR research is moving to magnetic field strengths of 7 T and beyond, the safety of subjects and MR technologists must be given the highest priority. Temporal adverse sensational effects resulting from exposures to ultra‐high magnetic fields, such as vertigo, dizziness, nausea, and metallic taste, have been widely reported 13,15‐19 . Consequently, an important question arises as to whether repeated exposures to ultra‐high static magnetic fields could ultimately cause some long‐term impairment.…”

Section: Discussionmentioning

confidence: 99%

Long‐term behavioral effects observed in mice chronically exposed to static ultra‐high magnetic fields

Tkáč

Benneyworth

Nichols-Meade

et al. 2021

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose The primary goal of this study was to investigate whether chronic exposures to ultra‐high B0 fields can induce long‐term cognitive, behavioral, or biological changes in C57BL/6 mice. Methods C57BL/6 mice were chronically exposed to 10.5‐T or 16.4‐T magnetic fields (3‐h exposures, two exposure sessions per week, 4 or 8 weeks of exposure). In vivo single‐voxel 1H magnetic resonance spectroscopy was used to investigate possible neurochemical changes in the hippocampus. In addition, a battery of behavioral tests, including the Morris water‐maze, balance‐beam, rotarod, and fear‐conditioning tests, were used to examine long‐term changes induced by B0 exposures. Results Hippocampal neurochemical profile, cognitive, and basic motor functions were not impaired by chronic magnetic field exposures. However, the balance‐beam–walking test and the Morris water‐maze testing revealed B0‐induced changes in motor coordination and balance. The tight‐circling locomotor behavior during Morris water‐maze tests was found as the most sensitive factor indexing B0‐induced changes. Long‐term behavioral changes were observed days or even weeks subsequent to the last B0 exposure at 16.4 T but not at 10.5 T. Fast motion of mice in and out of the 16.4‐T magnet was not sufficient to induce such changes. Conclusion Observed results suggest that the chronic exposure to a magnetic field as high as 16.4 T may result in long‐term impairment of the vestibular system in mice. Although observation of mice may not directly translate to humans, nevertheless, they indicate that studies focused on human safety at very high magnetic fields are necessary.

show abstract

Section: Discussionmentioning

confidence: 99%

Long‐term behavioral effects observed in mice chronically exposed to static ultra‐high magnetic fields

Tkáč

Benneyworth

Nichols-Meade

et al. 2021

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…Although an increase in physiologic side effects have been reported at UHF (dizziness, nausea and metallic taste) [ 83 , 84 ], patients’ experience seems to be similar to that perceived at lower field strengths [ 85 ].…”

Section: Limitationsmentioning

confidence: 99%

Musculoskeletal MRI at 7 T: do we need more or is it more than enough?

Aringhieri

Zampa

Tosetti³

2020

Eur Radiol Exp

View full text Add to dashboard Cite

Ultra-high field magnetic resonance imaging (UHF-MRI) provides important diagnostic improvements in musculoskeletal imaging. The higher signal-to-noise ratio leads to higher spatial and temporal resolution which results in improved anatomic detail and higher diagnostic confidence. Several methods, such as T2, T2*, T1rho mapping, delayed gadolinium-enhanced, diffusion, chemical exchange saturation transfer, and magnetisation transfer techniques, permit a better tissue characterisation. Furthermore, UHF-MRI enables in vivo measurements by low-γ nuclei ( 23 Na, 31 P, 13 C, and 39 K) and the evaluation of different tissue metabolic pathways. European Union and Food and Drug Administration approvals for clinical imaging at UHF have been the first step towards a more routinely use of this technology, but some drawbacks are still present limiting its widespread clinical application. This review aims to provide a clinically oriented overview about the application of UHF-MRI in the different anatomical districts and tissues of musculoskeletal system and its pros and cons. Further studies are needed to consolidate the added value of the use of UHF-MRI in the routine clinical practice and promising efforts in technology development are already in progress.

show abstract

“…With 7T MRI scanners from different vendors receiving clearance for clinical applications, it might be expected that 7T MRI will soon be adopted in clinical practice[ 7 , 8 , 17 , 18 ]. UHF MRI introduces several advantages, as well as some limitations, compared to lower-field imaging.…”

Section: Introductionmentioning

confidence: 99%

Cardiac functional magnetic resonance imaging at 7T: Image quality optimization and ultra-high field capabilities

Ibrahim

Arpinar

Muftuler

et al. 2020

WJR

View full text Add to dashboard Cite

BACKGROUND 7T cardiac magnetic resonance imaging (MRI) introduces several advantages, as well as some limitations, compared to lower-field imaging. The capabilities of ultra-high field (UHF) MRI have not been fully exploited in cardiac functional imaging. AIM To optimize 7T cardiac MRI functional imaging without the need for conducting B1 shimming or subject-specific tuning, which improves scan efficiency. In this study, we provide results from phantom and in vivo scans using a multi-channel transceiver modular coil. METHODS We investigated the effects of adding a dielectric pad at different locations next to the imaged region of interest on improving image quality in subjects with different body habitus. We also investigated the effects of adjusting the imaging flip angle in cine and tagging sequences on improving image quality, B1 field homogeneity, signal-to-noise ratio (SNR), blood-myocardium contrast-to-noise ratio (CNR), and tagging persistence throughout the cardiac cycle. RESULTS The results showed the capability of achieving improved image quality with high spatial resolution (0.75 mm × 0.75 mm × 2 mm), high temporal resolution (20 ms), and increased tagging persistence (for up to 1200 ms cardiac cycle duration) at 7T cardiac MRI after adjusting scan set-up and imaging parameters. Adjusting the imaging flip angle was essential for achieving optimal SNR and myocardium-to-blood CNR. Placing a dielectric pad at the anterior left position of the chest resulted in improved B1 homogeneity compared to other positions, especially in subjects with small chest size. CONCLUSION Improved regional and global cardiac functional imaging can be achieved at 7T MRI through simple scan set-up adjustment and imaging parameter optimization, which would allow for more streamlined and efficient UHF cardiac MRI.

show abstract

Safety Considerations of 7-T MRI in Clinical Practice

Cited by 63 publications

References 71 publications

Long‐term behavioral effects observed in mice chronically exposed to static ultra‐high magnetic fields

Long‐term behavioral effects observed in mice chronically exposed to static ultra‐high magnetic fields

Musculoskeletal MRI at 7 T: do we need more or is it more than enough?

Cardiac functional magnetic resonance imaging at 7T: Image quality optimization and ultra-high field capabilities

Contact Info

Product

Resources

About