Abstract
In vivo MRI has revolutionized the diagnosis and treatment of musculoskeletal disorders over
the past 3 decades. Traditionally performed at 1.5 T, MRI at higher field strengths
offers several advantages over lower field strengths including increased signal-to-noise
ratio, higher spatial resolution, improved spectral resolution for spectroscopy, improved
sensitivity for X-nucleus imaging, and decreased image acquisition times. However,
the physics of imaging at higher field strengths also presents technical challenges.
These include B0 and B1+ field inhomogeneity, design and construction of dedicated radiofrequency (RF) coils
for use at high field, increased chemical shift and susceptibility artifacts, increased
RF energy deposition (specific absorption rate), increased metal artifacts, and changes
in relaxation times compared with the lower field scanners. These challenges were
overcome in optimizing high-field (HF) (3 T) MRI over a decade ago. HF MRI systems
have since gained universal acceptance for clinical musculoskeletal imaging and have
also been widely utilized for the study of musculoskeletal anatomy and physiology.
Recently there has been an increasing interest in exploring musculoskeletal applications
of ultrahigh field (UHF) (7 T) systems. However, technical challenges similar to those
encountered when moving from 1.5 T to 3 T have to be overcome to optimize 7 T musculoskeletal
imaging. In this narrative review, we discuss the many potential opportunities and
technical challenges presented by the HF and UHF MRI systems. We highlight recent
developments in in vivo imaging of musculoskeletal tissues that benefit most from
HF imaging including cartilage, skeletal muscle, and bone.
Keywords
magnetic resonance imaging - high field imaging - musculoskeletal imaging - bone structure
- cartilage
