Advanced MR methods at ultra-high field (7 Tesla) for clinical musculoskeletal applications.

OBJECTIVES: This article provides an overview of the initial clinical results of musculoskeletal studies performed at 7 Tesla, with special focus on sodium imaging, new techniques such as chemical exchange saturation transfer (CEST) and T2* imaging, and multinuclear MR spectroscopy.
METHODS: Sodium imaging was clinically used at 7 T in the evaluation of patients after cartilage repair procedures because it enables the GAG content to be monitored over time. Sodium imaging and T2* mapping allow insights into the ultra-structural composition of the Achilles tendon and help detect early disease. Chemical exchange saturation transfer was, for the first time, successfully applied in the clinical set-up at 7 T in patients after cartilage repair surgery. The potential of phosphorus MR spectroscopy in muscle was demonstrated in a comparison study between 3 and 7 T, with higher spectral resolution and significantly shorter data acquisition times at 7 T.
RESULTS: These initial clinical studies demonstrate the potential of ultra-high field MR at 7 T, with the advantage of significantly improved sensitivity for other nuclei, such as (23)Na (sodium) and (31)P (phosphorus).
CONCLUSIONS: The application of non-proton imaging and spectroscopy provides new insights into normal and abnormal physiology of musculoskeletal tissues, particularly cartilage, tendons, and muscles. KEY POINTS : • 7 T magnetic resonance provides significantly improved sensitivity for ( 23 ) Na and ( 31 ) P. • Initial clinical studies have now demonstrated ultra-high field MR operating at 7 T. • 7 T provides new insights into normal and abnormal physiology of musculoskeletal tissues.