An orthesis for reproducible kinematic MR imaging of the shoulder

Thomas M 1 , Weller V 2 , Schulz T 3

1 Orthopädische Klinik und Poliklinik der Universität Leipzig (Direktor: Prof. Dr. G. von Salis-Soglio)
2 MSB Orthopädietechnik GmbH Leipzig
3 Klinik und Poliklinik für Diagnostische Radiologie der Universität Leipzig(Direktor: Prof. Dr. T. Kahn)

Summary

Thomas M, Weller V, Schulz T. An orthesis for reproducible kinematic MR imaging of the shoulder. Clinical Sports Medicine International (CSMI) 2004, 1: 15-21.

Background: In general the standard MRI diagnostic of the shoulder in a circumferential high-field, whole body MRI magnet is performed with adducted arm due to the magnet configuration. An alternative arm position is the ABER position. The patient’s hand is behind the head. Vertical and horizontal open, whole body MRI magnets allows new possibilities for MR imaging in other joint positions which are representative for diseases of the shoulder joint (e.g. impingement, rotator cuff disease, glenohumeral instability). An essential prerequisite for such investigations is a stable fixation of the arm by use of a MR-compatible device.

Objective: The purpose of this study was the development of an MR-compatible device for the positioning of the shoulder in an open, whole body MRI magnet. The device should be universally usable on men and women and be adaptable onto the different heights. Furthermore defined joint positions should be adjustable and the movements of the shoulder should be quantifiable.

Materials and methods: Materials of aluminum and brass were embedded into glycerol gelatine for the artifact diagnostic. The examination was performed in an open, whole body MRI system with 0.5 Tesla superconducting magnet (Signa SP/i, General Electric, Milwaukee, WI). Different pulse sequences (Spin-Echo, Fast Spin-Echo, Gradient Echo) were used. Only MR-compatible materials of aluminum and brass as well as materials of plastic and textile were used for the construction of the device for shoulder positioning. The correct function and the MR-­compatibility were verified.

Results: The device for shoulder positioning consists of three parts: the basis component, the universal component and the right and the left arm component. The device allows movements of the shoulder in all degrees of freedom. The axis of rotation of the device can be adjusted depending on the axis of rotation of the shoulder joint. The quantification of the joint movement is possible by use of a graduation in steps of 15 degrees. By use of the device artifact-free investigations of the shoulder can be peformed in functionally important joint positions (e.g. the apprehension-test position).

Conclusion: The development of a MR-compatible device for shoulder positioning in an open, whole body MR magnet is presented.

Keywords: shoulder, shoulder positioning device, magnetic resonance imaging, open MRI