The Experimental study on positioning of the surface coil for magnetic resonance imaging

Abstract

We examined the correlation between signal intensity and setting angulations for magnetic resonance imagesobtained using a surface coil, which had a three inch surface coil,and dual coil, which had a three inch surface coil and an anterior neck coil. We took T2-3D weighted, T2-2D weighted and T1-2D weighted images with the angulated three-inch surface coil at 0-90 degrees with the magnetic direction.
In every sequence, the maximum intensity with the dual coil was taken with angulations of 50-60 degrees. The intensity of the dual coil could be as much as the three times that of the single coil. As the angulations increased with the dual coil, the thickness of the effective intensity was decreased until it reached 50% of the maximum thickness. With the single coil it decreased until it reached 10%.
When using a high-resolution coil that cannot be setup parallel with the magnetic direction, we recommend using a dual coil rather than a single coil to increase the signal intensity. In the oral cavity, the intraoral coil should be used with the extraoral coil as the phased array coil. This is the optimum condition of coil angulation for taking high resolution images. Shika Igaku (J Osaka Odontol Soc) 2002 Dec; 65(3/4 combined): 266-274.