magnetic resonance imaging (MRI, diffusion-weighted MRI)

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Introduction

Also see principles of magnetic resonance imaging

Indications

clinical indications for MRI

*indications for contrast MRI imaging with gadolinium:*

* gadolinium is the enhancing agent commonly used for MRI superparamagnetic iron oxides is another enhancing agent[6]

Contraindications

(contraindications for MRI)[5]

Contrast MRI imaging with gadolinium:*

Advantages

* advantages of MRI over CT

Disadvantages

* limitations of MRI

Procedure

  • patient is advanced into bore of magnet in supine position on floating table
  • ear-plugs or ear-music systems are commonly used because of high noise level
  • entire exam takes 20-45 minutes
    • multiple imaging sequences in multiple planes
    • imaging sequences range from 1 second to 10 minutes
  • patients asked to remove jewlery, metallic objects, including cutaneous metal devices (nicotine patch)
  • patients to wear face mask with no metal during MRI exams[16] during COVID-19 pandemic

Notes

  • introduction of the 1.5 Tesla whole-body superconducting scanner in 1983
    • scanners are mostly found in specialized radiology departments & large imaging centers with radio frequency (RF)-shielded rooms[18]
  • 1st MRI FDA-approved for neonates July 2017[13]
  • 7 tesla device doubles magnetic field strength facilitating better visualization of smaller structures & subtle pathologies[14]
  • 0.05 Tesla whole body MRI, including T1-weighted, T2-weighted, & diffusion-weighted imaging augmented by deep learning AI[18]
    • no protective shielding is needed
    • patients & bystanders can safely use smart phones
    • scanner is safe for patients with implanted devices, inlcuding cochlear implant or pacemaker
    • metal on body or clothes also ok
    • no hearing protection is required, scanner is quiet
    • not yet FDA-approved
    • may be commercially available in a few years[18]
  • helium is used in cooling MRI scanners[19]

More general terms

More specific terms

Additional terms

References

  1. Introduction to Clinical Imaging, Radiology Syllabus, UCSF, 1993
  2. Jump up to: 2.0 2.1 2.2 Medical Knowledge Self Assessment Program (MKSAP) 11,16,17. American College of Physicians, Philadelphia 1998,2012,2015.
  3. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 2289
  4. Veterans Affairs (VA) National Center for Patient Safety Magnetic Resonance Imaging (MR) Hazard Summary http://www.patientsafety.gov/mrihazardsummary.html
  5. Jump up to: 5.0 5.1 UpToDate 14.1 http://www.utdol.com
  6. Jump up to: 6.0 6.1 Aguirre DA, Behling CA, Alpert E, Hassanein TI, Sirlin CB. Liver fibrosis: noninvasive diagnosis with double contrast material-enhanced MR imaging. Radiology. 2006 May;239(2):425-37. PMID: https://www.ncbi.nlm.nih.gov/pubmed/16641352
  7. Jump up to: 7.0 7.1 7.2 Sommer T et al, Strategy for safe performance of extrathoracix magnetic resonance imaging at 1.5 tesla in the presence of cardiac pacemakers in non-pacemaker-dependent patients: A prospective study with 115 examinations. Circulation 2006, 114:1285 PMID: https://www.ncbi.nlm.nih.gov/pubmed/16966587
    Nazarian S et al, Clinical utility and safety of a protocol for non-cardiac magnetic resonance imaging of patients with permanent pacemakers and implantable-cardioverter defibrillators at 1.5 tesla. Circulation 2006, 114:1277 PMID: https://www.ncbi.nlm.nih.gov/pubmed/16966586
  8. Jump up to: 8.0 8.1 Nazarian S et al. A prospective evaluation of a protocol for magnetic resonance imaging of patients with implanted cardiac devices. Ann Intern Med 2011 Oct 4; 155:415 PMID: https://www.ncbi.nlm.nih.gov/pubmed/21969340
    Reynolds MR and Zimetbaum P. Magnetic resonance imaging and cardiac devices: How safe is safe enough? Ann Intern Med 2011 Oct 4; 155:470. PMID: https://www.ncbi.nlm.nih.gov/pubmed/21969346
  9. Jump up to: 9.0 9.1 9.2 9.3 Kim BG et al Adverse Events and Discomfort During Magnetic Resonance Imaging in Cochlear Implant Recipients. JAMA Otolaryngol Head Neck Surg. November 20, 2014 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/2541181 <Internet> http://archotol.jamanetwork.com/article.aspx?articleid=1936465
    Kanal E Magnetic Resonance Imaging in Cochlear Implant Recipients. Pros and Cons. JAMA Otolaryngol Head Neck Surg. November 20, 2014 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/25412437 <Internet> http://archotol.jamanetwork.com/article.aspx?articleid=1936463
  10. Jump up to: 10.0 10.1 Ray JG, Vermeulen MJ, Bharatha A et al Association Between MRI Exposure During Pregnancy and Fetal and Childhood Outcomes. JAMA. 2016;316(9):952-961 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/27599330 <Internet> http://jama.jamanetwork.com/article.aspx?articleid=2547756
  11. Jump up to: 11.0 11.1 11.2 FDA Safety Communication. Jan 11, 2017 Safety Concerns with Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment. http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm536518.htm
  12. Jump up to: 12.0 12.1 Russo RJ, Costa HS, Silva PD et al Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator. N Engl J Med 2017; 376:755-764. February 23, 2017 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/28225684 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMoa1603265
  13. Jump up to: 13.0 13.1 FDA News Release. July 20, 2017 FDA clears first neonatal magnetic resonance imaging device. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm567840.htm
  14. Jump up to: 14.0 14.1 FDA News Release. Oct 12, 2017 FDA clears first 7T magnetic resonance imaging device. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm580154.htm
  15. Jump up to: 15.0 15.1 Callaghan MF, Negus C, Leff AP et al Safety of Tattoos in Persons Undergoing MRI. N Engl J Med 2019; 380:495-496. Jan 31, 2019 PMID: https://www.ncbi.nlm.nih.gov/pubmed/30699316 https://www.nejm.org/doi/full/10.1056/NEJMc1811197
  16. Jump up to: 16.0 16.1 FDA Safety Communication. Dec 7, 2020 Wear Face Masks with No Metal During MRI Exams. https://www.fda.gov/medical-devices/safety-communications/wear-face-masks-no-metal-during-mri-exams-fda-safety-communication
  17. Jump up to: 17.0 17.1 Schaller RD, Brunker T, Riley MP et al Magnetic Resonance Imaging in Patients With Cardiac Implantable Electronic Devices With Abandoned Leads. JAMA Cardiol. Published online February 17, 2021 PMID: https://www.ncbi.nlm.nih.gov/pubmed/33595595 https://jamanetwork.com/journals/jamacardiology/fullarticle/2776350
  18. Jump up to: 18.0 18.1 18.2 18.3 Szalinski C 'Big Breakthrough': New Low-Field MRI Is Safer and Easier. Medscape. May 20, 2024 https://www.medscape.com/viewarticle/big-breakthrough-new-low-field-mri-safer-and-easier-2024a10009hb
    Zhao Y, Ding Y, Lau V, Man C, Su S, Xiao L, Leong ATL, Wu EX. Whole-body magnetic resonance imaging at 0.05 Tesla. Science. 2024 May 10;384(6696) PMID: https://www.ncbi.nlm.nih.gov/pubmed/38723062 https://www.science.org/doi/10.1126/science.adm7168
  19. Jump up to: 19.0 19.1 Nature. 2024. Dec 12.