Presentation Format: Educational poster presentation.
Purpose or Learning Objective: (1) To demonstrate that dynamic magnetic resonance imaging (MRI) assessment of the wrist can play an important role in the evaluation of carpal instability, in particular in scapholunate instability, and in extensor carpi ulnaris tendon instability. (2) To describe the principal findings that need to be evaluated in the dynamic MRI study of the wrist.
Methods or Background: Carpal instability is a complex condition in which wrist motion and/or loading produces mechanical dysfunction, giving rise to weakness, pain, and decreased function. , Several authors recently showed that MRI assessment of the wrist during active motion may be valuable in the evaluation of (1) patients with clinical suspicion of carpal instability but with absent or scarcely significant findings on conventional examinations, and in (2) patients with wrist instability who need an additional examination, in particular in planning for surgical treatment.
Wrist dynamic evaluation also requires a deep knowledge of the complex anatomy and biomechanics of the wrist structures.
Results or Findings: Currently, the most used sequences in the dynamic MRI assessment of the wrist, due to their high temporal resolution, are the balanced steady-state free precession sequence, radiofrequency-spoiled sequence, and ultrafast gradient-echo sequence.
Dynamic MRI evaluation of the wrist, also related to clinical suspicion, is performed during active supination/pronation, radial/ulnar deviation, “clenched fist,” and volar flexion/dorsiflexion maneuvers.
The main findings that can be evaluated from the resulting images are distal radioulnar joint congruity, extensor carpi ulnaris tendon translation, transverse translation of the trapezium at the scaphotrapezium joint, capitate-to-triquetrum distance, the scapholunate interval, and the scapholunate, radiolunate, and capitolunate angles.
These measurements can be related to lunate type, ulnar variance, and wrist kinematic pattern to obtain an overall assessment of wrist instability.
Conclusion: Dynamic MRI study of the wrist is easy to perform and not time consuming. It can be included in a investigative MRI protocol in suspected wrist instability. Dynamic evaluation is very useful because resulting anatomical images enable the measurement of metrics commonly evaluated for dynamic wrist instability, and it can also show the presence of findings indicative of instability that cannot be seen on conventional examination.
