Multiple different methods are now available which can been used to accelerate musculoskeletal MRI and improve the efficiency of MRI protocols for evaluating musculoskeletal diseases without compromising image quality or diagnostic performance. These methods including the use of highly efficient spiral and radial k-space trajectories, 3T scanners, parallel imaging acceleration, isotropic resolution imaging, compressed sensing k-space under-sampling, and T2 shuffling.
Targeted Audience: This lecture is targeted toward radiologists who use MRI for evaluating musculoskeletal diseases in clinical practice.
Objective: This lecture will provide radiologists with information to improve the efficiency of their MRI protocols for evaluating musculoskeletal diseases in clinical practice.
Purpose: The objective of this lecture is to describe multiple different methods that can be used to accelerate musculoskeletal MRI with the intent to improve the efficiency of MRI protocols for evaluating musculoskeletal diseases without significantly compromising image quality or diagnostic performance.
Methods: A thorough review of the literature was performed to identify multiple different methods that can be used to accelerate musculoskeletal MRI.
Results and Discussion: Musculoskeletal MRI is typically performed using Cartesian-based two-dimensional fast spin-echo sequences with different tissue contrast that are repeated in multiple planes. This acquisition strategy is rather time-consuming and results in long MRI examination times which are uncomfortable and inconvenient for patients and reduce the clinical efficiency of the MRI scanner. Multiple different methods have been used to accelerate musculoskeletal MRI. Initial methods included the use of sequences with spiral and radial k-space trajectories which are more efficient at acquiring image data when compared to Cartesian-based sequences. The recent widespread availability of 3T scanners has also resulted in acceleration of musculoskeletal MRI as the improved signal-to-noise ratio allows for a reduction in the number of signal averages needed to acquire high quality images using Cartesian-based two-dimensional fast spin-echo sequences. Parallel imaging techniques have also been used to accelerate both morphologic and quantitative musculoskeletal MRI. The use of parallel imaging leads to a reduction in signal-to-noise ratio, but this loss in signal can be offset by the use of high strength 3T scanners and multi-channel coils developed to image specific body parts. Parallel imaging has been used to accelerate two-dimensional fast spin-echo sequences as well as three-dimensional morphologic and quantitative sequences. An additional method for accelerating musculoskeletal imaging is to utilize isotropic resolution imaging. Isotropic resolution three-dimensional fast spin-echo sequences have been developed using parallel imaging acceleration and are now commercially available on most MRI vendor platforms. The volumetric source data can be used to create multi-planar reformat images following a single acquisition which eliminates the need to repeat sequences with identical tissue contrast in multiple planes. More recently, compressed sensing k-space under-sampling has been used to accelerate both morphologic and quantitative musculoskeletal MRI. While the use of compressed sensing can reduce scan time without a loss in signal-to-noise ratio, the under-sampling of k-space results in increased image blurring. T2 shuffling is another recently described technique which shows great promise for accelerating musculoskeletal MRI but is still in the developmental stage.
Conclusions: Multiple different methods are now available which can been used to accelerate musculoskeletal MRI and improve the efficiency of MRI protocols for evaluating musculoskeletal diseases without significantly compromising image quality or diagnostic performance.