Magnetic resonance imaging using microfabricated planar coils

We present magnetic resonance imaging (MRI) experiments performed using microfabricated planar coils. The coils are fabricated on a glass wafer by electroplating copper in an SU-8 photoepoxy mold, resulting in a low series resistance. The images are acquired using a gradient echo sequence at 4.7 T, with a 180 mT/m actively shielded gradient system. In a first experiment, an image of a phantom filled with water is obtained with a resolution of 21/spl times/29/spl times/170 cubic micrometers within an acquisition time of 15 minutes, using a 2-turn, 2 mm diameter micromachined planar coil. We also obtain an image of banana skin with an in-plane resolution of 62/spl times/44 squared micrometers, using a 3-turn, 500 micrometers diameter coil. Compared to solenoid geometries, planar coils have a high sensitivity close to their surface; however as the distance from the coil surface is increased, the sensitivity deteriorates rapidly. Therefore, miniaturized planar coils are especially suited for high-resolution imaging of surface samples.