The advantages of a spine coil over a torso coil in magnetic resonance imaging examination of the sternoclavicular joints

Purpose
There are two standard methods for an magnetic resonance imaging (MRI) examination of the sternoclavicular joints: with loop coils and the patient in the prone position, or with torso coils with the patient in a supine position. In some centres these joints are examined with the spine coil in a patient laying prone. There are no reports on the advantages of this method. Our hypothesis is that despite different MRI systems, application of a spine coil will improve examination quality.

Material and methods
Twenty-one healthy volunteers (10 female, 11 male, mean age 25 years) were randomised into three groups and scanned using three different MRI scanners (1.5T: Siemens Avanto, Philips Ingenia, 3.0T: Philips Achieva). Each volunteer was examined twice: using a standard protocol with a torso coil and with a spine coil, in prone position. The two groups were compared with regard to the intensity of motion artefacts using the χ2 test, and to the signal-to-noise ratio with the Wilcoxon signed-rank test.

Results
Application of a spine coil resulted in a significant decrease in the number of motion artefacts in all three planes (axial: p = 0.0004; sagittal: p < 0.0001; coronal: p = 0.0054). Moreover, the signal-to-noise ratio was significantly increased with the application of a spine coil (28.6 ± 8.6 vs. 18.5 ± 7.3, respectively; p = 0.0002).

Conclusions
Application of a spine coil with the patient in a prone position is suitable for MRI evaluation of the sterno­clavicular joints. It allows a higher signal-to-noise ratio and a lower intensity of motion artefacts to be obtained compared to a torso coil.