William Timothy Barber, 50PO Box 533, Onset, MA 02558

5742164, Apr 21, 1998

Dec 28, 1995

8/579755

Peter B. Roemer - North Andover MA
William D. Barber - Clifton Park NY

General Electric Company - Milwaukee WI

G01V 300
G01V 314

324318

The invention is directed to a gradient coil assembly for MR imaging which includes a gradient coil set comprising inner and outer gradient coils, the inner gradient coil located within the outer gradient coil and surrounding or otherwise proximate to an imaging volume. The system further includes means for selectively energizing the inner and outer gradient coils to generate a resultant gradient field in the imaging volume. The energized inner and outer gradient coils are also disposed to collectively generate an eddy current field component in a region between the outer coil and a conductive structure spaced-apart therefrom when the inner gradient coil is displaced along an axis from a specified position with respect to the outer gradient coil. A compensation coil is selectively positioned with respect to the inner and outer gradient coils, and means are provided for applying a compensation current to the compensation coil to generate a magnetic field which substantially cancels the eddy current component, the compensation current and the displacement of the inner coil along the axis from the specified position having a specified relationship.