Opportunities in Interventional and Diagnostic Imaging by Using High-Performance Low-Field-Strength MRI

Low-field MRI combined with contemporary high-performance MRI hardware and advanced image acquisition and reconstruction strategies has advantages for some technically demanding applications including MRI-guided interventions, imaging anatomy near air-tissue interfaces, and efficient image acquisition methods.


Commercial low-field-strength MRI systems are generally not equipped with state-of-the-art MRI hardware, and are not suitable for demanding imaging techniques. An MRI system was developed that combines low field strength (0.55 T) with high-performance imaging technology.


To evaluate applications of a high-performance low-field-strength MRI system, specifically MRI-guided cardiovascular catheterizations with metallic devices, diagnostic imaging in high-susceptibility regions, and efficient image acquisition strategies.

Materials and Methods

A commercial 1.5-T MRI system was modified to operate at 0.55 T while maintaining high-performance hardware, shielded gradients (45 mT/m; 200 T/m/sec), and advanced imaging methods. MRI was performed between January 2018 and April 2019. T1, T2, and T2* were measured at 0.55 T; relaxivity of exogenous contrast agents was measured; and clinical applications advantageous at low field were evaluated.


There were 83 0.55-T MRI examinations performed in study participants (45 women; mean age, 34 years ± 13). On average, T1 was 32% shorter, T2 was 26% longer, and T2* was 40% longer at 0.55 T compared with 1.5 T. Nine metallic interventional devices were found to be intrinsically safe at 0.55 T (<1°C heating) and MRI-guided right heart catheterization was performed in seven study participants with commercial metallic guidewires. Compared with 1.5 T, reduced image distortion was shown in lungs, upper airway, cranial sinuses, and intestines because of improved field homogeneity. Oxygen inhalation generated lung signal enhancement of 19% ± 11 (standard deviation) at 0.55 T compared with 7.6% ± 6.3 at 1.5 T (P = .02; five participants) because of the increased T1 relaxivity of oxygen (4.7e−4 mmHg−1sec−1). Efficient spiral image acquisitions were amenable to low field strength and generated increased signal-to-noise ratio compared with Cartesian acquisitions (P < .02). Representative imaging of the brain, spine, abdomen, and heart generated good image quality with this system.


This initial study suggests that high-performance low-field-strength MRI offers advantages for MRI-guided catheterizations with metal devices, MRI in high-susceptibility regions, and efficient imaging.

© RSNA, 2019

Online supplemental material is available for this article.

See also the editorial by Grist in this issue.


  • 1. Marques JP, Simonis FFJ, Webb AG. Low-field MRI: An MR physics perspective. J Magn Reson Imaging 2019;49(6):1528–1542.
  • 2. Simonetti OP, Ahmad R. Low-Field Cardiac Magnetic Resonance Imaging: A Compelling Case for Cardiac Magnetic Resonance’s Future. Circ Cardiovasc Imaging 2017;10(6):e005446.
  • 3. Rashid S, Han F, Gao Y, et al. Cardiac balanced steady-state free precession MRI at 0.35 T: a comparison study with 1.5 T. Quant Imaging Med Surg 2018;8(7):627–636.
  • 4. Rogers T, Lederman RJ. Interventional CMR: Clinical applications and future directions. Curr Cardiol Rep 2015;17(5):31.
  • 5. Konings MK, Bartels LW, Smits HF, Bakker CJ. Heating around intravascular guidewires by resonating RF waves. J Magn Reson Imaging 2000;12(1):79–85.
  • 6. ASTM International. F2182-09 Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging. West Conshohocken, Pa: ASTM International, 2009.
  • 7. Campbell-Washburn AE, Rogers T, Stine AM, et al. Right heart catheterization using metallic guidewires and low SAR cardiovascular magnetic resonance fluoroscopy at 1.5 Tesla: first in human experience. J Cardiovasc Magn Reson 2018;20(1):41.
  • 8. Velasco Forte MN, Pushparajah K, Schaeffter T, et al. Improved passive catheter tracking with positive contrast for CMR-guided cardiac catheterization using partial saturation (pSAT). J Cardiovasc Magn Reson 2017;19(1):60.
  • 9. Johnson SR, Taveira-DaSilva AM, Moss J. Lymphangioleiomyomatosis. Clin Chest Med 2016;37(3):389–403.
  • 10. Edelman RR, Hatabu H, Tadamura E, Li W, Prasad PV. Noninvasive assessment of regional ventilation in the human lung using oxygen-enhanced magnetic resonance imaging. Nat Med 1996;2(11):1236–1239.
  • 11. Dietrich O, Gaass T, Reiser MF. T1 relaxation time constants, influence of oxygen, and the oxygen transfer function of the human lung at 1.5T-A meta-analysis. Eur J Radiol 2017;86:252–260.
  • 12. Bulte D, Chiarelli P, Wise R, Jezzard P. Measurement of cerebral blood volume in humans using hyperoxic MRI contrast. J Magn Reson Imaging 2007; 26(4):894–899.
  • 13. Lingala SG, Sutton BP, Miquel ME, Nayak KS. Recommendations for real-time speech MRI. J Magn Reson Imaging 2016;43(1):28–44.
  • 14. Lingala SG, Zhu Y, Kim YC, Toutios A, Narayanan S, Nayak KS. A fast and flexible MRI system for the study of dynamic vocal tract shaping. Magn Reson Med 2017;77(1):112–125.
  • 15. Feng L, Grimm R, Block KT, et al. Golden-angle radial sparse parallel MRI: combination of compressed sensing, parallel imaging, and golden-angle radial sampling for fast and flexible dynamic volumetric MRI. Magn Reson Med 2014;72(3):707–717.
  • 16. Nayak KS, Hargreaves BA, Hu BS, Nishimura DG, Pauly JM, Meyer CH. Spiral balanced steady-state free precession cardiac imaging. Magn Reson Med 2005;53(6):1468–1473.
  • 17. Li Z, Hu HH, Miller JH, et al. A Spiral Spin-Echo MR Imaging Technique for Improved Flow Artifact Suppression in T1-Weighted Postcontrast Brain Imaging: A Comparison with Cartesian Turbo Spin-Echo. AJNR Am J Neuroradiol 2016;37(4):642–647.
  • 18. Campbell-Washburn AE, Xue H, Lederman RJ, Faranesh AZ, Hansen MS. Real-time distortion correction of spiral and echo planar images using the gradient system impulse response function. Magn Reson Med 2016;75(6):2278–2285.
  • 19. Macovski A. Noise in MRI. Magn Reson Med 1996;36(3):494–497.
  • 20. Robson PM, Grant AK, Madhuranthakam AJ, Lattanzi R, Sodickson DK, McKenzie CA. Comprehensive quantification of signal-to-noise ratio and g-factor for image-based and k-space-based parallel imaging reconstructions. Magn Reson Med 2008;60(4): 895–907.
  • 21. Lim Y, Lingala SG, Narayanan SS, Nayak KS. Dynamic off-resonance correction for spiral real-time MRI of speech. Magn Reson Med 2019;81(1):234–246.
  • 22. Rohrer M, Bauer H, Mintorovitch J, Requardt M, Weinmann HJ. Comparison of magnetic properties of MRI contrast media solutions at different magnetic field strengths. Invest Radiol 2005;40(11):715–724.
  • 23. Vasanawala SS, Nguyen KL, Hope MD, et al. Safety and technique of ferumoxytol administration for MRI. Magn Reson Med 2016;75(5):2107–2111.
  • 24. Finn JP, Nguyen KL, Han F, et al. Cardiovascular MRI with ferumoxytol. Clin Radiol 2016;71(8):796–806.
  • 25. Richardson OC, Bane O, Scott ML, et al. Gadofosveset-based biomarker of tissue albumin concentration: Technical validation in vitro and feasibility in vivo. Magn Reson Med 2015;73(1):244–253.
  • 26. Opina AC, Wong KJ, Griffiths GL, et al. Preparation and long-term biodistribution studies of a PAMAM dendrimer G5-Gd-BnDOTA conjugate for lymphatic imaging. Nanomedicine (Lond) 2015;10(9):1423–1437.
  • 27. Longmire MR, Ogawa M, Choyke PL, Kobayashi H. Dendrimers as high relaxivity MR contrast agents. Wiley Interdiscip Rev Nanomed Nanobiotechnol 2014;6(2):155–162.
  • 28. Ratnayaka K, Faranesh AZ, Guttman MA, Kocaturk O, Saikus CE, Lederman RJ. Interventional cardiovascular magnetic resonance: still tantalizing. J Cardiovasc Magn Reson 2008;10(1):62.
  • 29. Mirhej ME. Proton Spin Relaxation By Paramagnetic Molecular Oxygen. Can J Chem 1965;43(5):1130–1138.
  • 30. van Osch MJP, Webb AG. Safety of Ultra-High Field MRI: What are the Specific Risks? Curr Radiol Rep 2014;2(8):61.
  • 31. Price DL, De Wilde JP, Papadaki AM, Curran JS, Kitney RI. Investigation of acoustic noise on 15 MRI scanners from 0.2 T to 3 T. J Magn Reson Imaging 2001;13(2): 288–293.
  • 32. Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med 2004;52(1):141–146.

Article History

Received: Feb 26 2019
Revision requested: Apr 15 2019
Revision received: Aug 6 2019
Accepted: Aug 15 2019
Published online: Oct 01 2019
Published in print: Nov 2019