Description
MRI scanners with a field strength of greater than 1.0 Tesla (T) are considered high field. The typical high field MRI units in clinical practice range between 1.0 – 3.0 Tesla. In October 2017 the FDA cleared the first 7 T MRI units.1 The definition of mid and low field MRI is more variable with mid field units having a lower field strength range of 0.3 to 0.5 and an upper limit under 1.0 T. Low field units have field strengths below 0.3 to 0.2 T. The major disadvantage of low field strength MRI relative to higher field scanners is lower signal to noise ratios, less homogeneity in the magnetic field, lower detection of calcification, hemorrhage, or gadolinium enhancement. Lee et al showed that low field (< 0.5 T) units were effective in evaluating medial meniscal, anterior cruciate ligament, and rotator cuff tears but not effective for evaluating lateral meniscal tears, osteochondral defects, or shoulder superior labrum-anterior posterior (SLAP) ligament complex pathology.^2,3

GENERAL INFORMATION

• It is an expectation that all patients receive care/services from a licensed clinician. All appropriate supporting documentation, including recent pertinent office visit notes, laboratory data, and results of any special testing must be provided. If applicable: All prior relevant imaging results and the reason that alternative imaging cannot be performed must be included in the documentation submitted.
• Where a specific clinical indication is not directly addressed in this guideline, medical necessity determination will be made based on widely accepted standard of care criteria. These criteria are supported by evidence-based or peer-reviewed sources such as medical literature, societal guidelines and state/national recommendations.
   

Policy
Low-field MRI services are not considered to be MEDICALLY NECESSARY.

References

1. FDA News Release: FDA clears first 7T magnetic resonance imaging device. U.S. Food & Drug Administration. Updated October 12, 2017. Accessed December 14, 2022. https://www.fda.gov/news-events/press-announcements/fda-clears-first-7t-magnetic- resonance-imaging-device
2. Lee CS, Davis SM, McGroder C, Stetson WB, Powell SE. Analysis of Low-Field Magnetic Resonance Imaging Scanners for Evaluation of Knee Pathology Based on Arthroscopy. Orthop J Sports Med. 2013;1(7):2325967113513423-2325967113513423. doi:10.1177/2325967113513423
3. Lee CS, Davis SM, McGroder C, et al. Analysis of Low-Field MRI Scanners for Evaluation of Shoulder Pathology Based on Arthroscopy. Orthop J Sports Med. 2014;2(7):2325967114540407- 2325967114540407. doi:10.1177/2325967114540407

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

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