Most hospitals use MRI systems with field strengths between 1.5T and 3T. However, now there are Ultra high-field MRI systems that produce magnetic fields at 7T.
Ultra high-field MRI systems were just approved for clinical imaging in 2020, so they aren’t common in hospital settings yet, but it’s good to understand their capabilities.
MRI image quality is dependent upon the strength of the magnetic field. Different magnetic field strengths are used for different purposes. Let’s take a closer look at the four types of magnetic field strengths for MRI.
- Low-field MRIs produce magnetic fields less than 0.3T. Since scan speed is dependent upon the strength of the magnetic field, these low-field MRI scans take longer to perform. They are ideal for extremity images of hands, arms, legs and feet.
- Medium-field MRIs produce magnetic fields between 0.3T-1T. These are usually open systems so the patient isn’t completely enclosed. They are commonly used for images of the torso and head.
- High-field MRIs produce magnetic fields between 1T-3T. They are closed MRI systems, so the patient is surrounded by the magnet except for where they entered on their back. The system creates higher resolution images so it’s easier to diagnose certain conditions.
- Ultra high-field MRIs produce magnetic fields at 7T or higher. The most powerful MRI systems available, they are ideal for diagnosing and tracking neurological conditions.
A 7T MRI captures anatomical images and functional images that are more than twice the resolution of those generated by a 1.5T system. This allows physicians to make much more accurate diagnoses in patients with musculoskeletal and neurological conditions. Ultra high-field MRIs can diagnose and track epilepsy, Alzheimer’s disease, Parkinson’s disease, brain tumors, cerebrovascular diseases, traumatic brain injuries and more. In addition, a 7T MRI systems can be used to perform a virtual biopsy to assess Multiple Sclerosis and visualize cortical lesions and central veins in white matter lesions.
In addition, an Ultra high-field MRI can capture non-invasive, detailed pictures for orthopedic surgeons. Using a 7T MRI, the surgeon would get to the source of a patient’s knee pain, thanks to detailed images of the trabecular bone, tendon and soft tissue.
One of the surprising things about Ultra high-field MRIs is that the magnets used in 7T MRI system are 50% lighter than the magnets used in previous MRI systems. You don’t need a significantly larger space for Ultra high-field MRI systems and you don’t have to refill the system’s liquid helium more often either—thanks to the use of zero helium boil-off technology.
What Are The Disadvantages of Ultra High-Field MRI Systems?
- The cost of a 7T MRI is significantly higher—almost twice as expensive as a 3T system. It can cost $7-$12 million for a 7T MRI system.
- The specific absorption rate (SAR) is much higher because of the more powerful magnetic field produced by a 7T system.
- The FDA set SAR limits to make sure patients are safe during high-powered MRI scans. 7T systems are equipped with monitoring systems to ensure SAR limits aren’t surpassed.
- Ferrous metal objects are more susceptible to the magnetic field products by 7T MRI systems. As long as safety precautions are used, there shouldn’t be a risk.
Is An Ultra High-Field MRI Right For You?
If you see a lot of patients with neurological diseases or musculoskeletal conditions, a 7T MRI system might be worth the expense. If not, a 1.5T or 3T MRI is capable of providing the high-quality imaging you need for diagnostics.
Talk to An Expert
Whether you offer an MRI Suite or Mobile MRI unit, you want to be confident that you are providing the medical imaging your patients need. Atlantis Worldwide has been helping healthcare professionals choose the right medical imaging equipment to fit their performance needs and budget limitations. Oftentimes, a used or refurbished MRI, CT Scanner or other medical imaging system is the perfect solution. Talk to Atlantis Worldwide today.
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Meet the author: Vikki Harmonay
