U.S. Philips Corporation

Tatjana Claasen-Vujcic

Gerardus Nerius Peeren

Gerardus B Mulder

Magnetic resonance apparatus includes a magnet system for generating a steady magnetic field in a measuring space, which steady magnetic field is oriented mainly parallel to one of the axes of an orthogonal coordinate system, a gradient system with gradient coil systems and with a controlled source for supplying the gradient coil systems with excitation currents with a predetermined variation in time. The gradient coil systems include a number of linear gradient coil systems, each of which is arranged to generate a main gradient field which is dependent on the location of the field in the measuring space in such a manner that a magnetic field formed by superposition of one of the main gradient fields on the steady magnetic field can be described, as a function of the coordinates of the coordinate system, as a series containing first-order terms and higher-order terms, the first-order terms having predetermined coefficients which are equal to zero for two of the coordinates. The gradient system is arranged so that at least a part of the second-order terms of the series describing the magnetic field formed by superposition of the magnetic fields generated by the gradient system on the steady magnetic field have predetermined coefficients. The undesirable effects of concomitant gradient fields can thus be counteracted.

Magnetic resonance apparatus

Magnetic apparatus resonance includes a mainly cylindrical RF coil (9) which has a central axis (35) extending in its longitudinal direction and comprises a number of axial conductor elements (37) which extend parallel to the central axis across a mainly cylindrical surface, and also comprises end conductor elements which extend around the central axis near the ends of the axial conductor elements. The axial conductor elements (37) are distributed across the circumference of the cylinder in such a manner that they occupy predetermined positions relative to a zero position (39). The RF coil (9) is arranged to generate a substantially sinusoidal current distribution as a function of the position of the axial conductor elements (37) on the circumference of the cylinder, expressed as the angle (.alpha.) of this position relative to the zero position (39), in order to enable a substantially uniform RF magnetic field, oriented perpendicularly to the cylinder axis (35), to be generated and/or received. Each end conductor element consists of a number of loop conductor segments (43), each of which interconnects the corresponding ends of two axial conductor elements (37). At least some of the axial conductor elements (37) constitute, together with the loop conductor segments (43) connected to their ends, a coil element (44) which is composed of a number of turns of an elongate electric conductor (45), all coil elements thus formed being electrically connected in series.

Growing community of inventors

Amersfoort, Netherlands

Tatjana Claasen-Vujcic