Echo planar imaging sequences were developed for a 9.4 Tesla vertical standard bore (~54 mm) superconducting magnet using an unshielded gradient coil. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (39 mm OD, 32 mm ID) and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact free and demonstrated the promise of our approach.
