Real-time three-dimensional MRI for the assessment of dynamic carpal instability

Abstract

BackgroundCarpal instability is defined as a condition where wrist motion and/or loading creates mechanical dysfunction, resulting in weakness, pain and decreased function. When conventional methods do not identify the instability patterns, yet clinical signs of instability exist, the diagnosis of dynamic instability is often suggested to describe carpal derangement manifested only during the wrist’s active motion or stress. We addressed the question: can advanced MRI techniques provide quantitative means to evaluate dynamic carpal instability and supplement standard static MRI acquisition? Our objectives were to (i) develop a real-time, three-dimensional MRI method to image the carpal joints during their active, uninterrupted motion; and (ii) demonstrate feasibility of the method for assessing metrics relevant to dynamic carpal instability, thus overcoming limitations of standard MRI.MethodsTwenty wrists (bilateral wrists of ten healthy participants) were scanned during radial-ulnar deviation and clenched-fist maneuvers. Images resulting from two real-time MRI pulse sequences, four sparse data-acquisition schemes, and three constrained image reconstruction techniques were compared. Image quality was assessed via blinded scoring by three radiologists and quantitative imaging metrics.ResultsReal-time MRI data-acquisition employing sparse radial sampling with a gradient-recalled-echo acquisition and constrained iterative reconstruction appeared to provide a practical tradeoff between imaging speed (temporal resolution up to 135 ms per slice) and image quality. The method effectively reduced streaking artifacts arising from data undersampling and enabled the derivation of quantitative measures pertinent to evaluating dynamic carpal instability.ConclusionThis study demonstrates that real-time, three-dimensional MRI of the moving wrist is feasible and may be useful for the evaluation of dynamic carpal instability.

Dynamic MRI for articulating joint evaluation on 1.5 T and 3.0 T scanners: setup, protocols, and real-time sequences

“…Three gradient echo sequences typically available on MRI scanners are suitable for real-time dynamic MRI and have already been used in previous studies to understand in vivo joint biomechanics. These are balanced steady-state free precession (SSFP) sequence [26,[28][29][30][31][32][33], RF-spoiled sequence [29,[34][35][36], and ultrafast gradient echo (UFGE) sequence [5,37], with different acronyms used by each MRI scanner manufacturer (Table 1).…”

“…Cartesian and radial sampling of the k-space were both used for real-time dynamic MRI. Radial sampling was particularly suitable for real-time RF-spoiled sequences at 3.0 T [29,35], allowing an increase in temporal resolution without image quality deterioration with the use of constrained iterative reconstruction [29]. Such iterative reconstruction of real-time images often requires the addition of graphic processing units to the current MRI systems [45,46].…”

“…Furthermore, the addition of the dynamic sequence should not substantially increase the total acquisition time. The RF coils used for real-time dynamic MRI make it possible to acquire standard static images with high image quality and thus can be used for both static and dynamic acquisitions at the same time and with the same setup [5,28,29,37].…”

“…The hand can also be positioned within a head coil to investigate all degrees of freedom ( Fig. 7a) [29,33], whereas Kaiser et al used an extremity coil to explore wrist pronation-supination [32]. Given the difference between the coil size and the small joint volume, the use of pads or foams to hold the hand in a central position within the coil and to avoid undesired motion is required (Fig.…”

Imaging of Carpal Instabilities

“…Clinical applicability has been shown for either technique in recent years. However, both dynamic CT and MRI are still considered specialized procedures not regularly performed in the clinical routine [21,22].…”