초록 ▼

A patient is disposed on a patient couch (A) and positioned longitudinally and vertically to bring a region of interest within the patient into a gap between a pair of magnetic pole pieces (20, 22). Magnetic field driver(s) (50′, 50, 52) generates a magnetic field through a U-shaped ferrous member (

A patient is disposed on a patient couch (A) and positioned longitudinally and vertically to bring a region of interest within the patient into a gap between a pair of magnetic pole pieces (20, 22). Magnetic field driver(s) (50′, 50, 52) generates a magnetic field through a U-shaped ferrous member (B) connected with the pole pieces and through the gap therebetween. The U-shaped ferrous member extends below the gap such that open access is provided to the patient from above. Shielding coils (62, 64, 66) are disposed between the U-shaped ferrous portion and the gap to compensate for distortion of the magnetic field in the gap attributable to magnetic flux through the U-shaped member. Magnetic resonance is excited in the region of interest of the patient between the pole pieces and magnetic resonance signals emanating therefrom are received, such as with a crossed elliptical quadrature coil (72). The received magnetic resonance signals are processed by processing circuitry (E) and image representations for display on a monitor (82).

대표청구항 ▼

A magnetic resonance imaging apparatus comprising: a patient supporting couch having a generally horizontal patient supporting surface, a longitudinal axis, and a transverse axis, whereby a patient is disposable on the patient supporting surface with its head and feet along the longitudinal axis and

A magnetic resonance imaging apparatus comprising: a patient supporting couch having a generally horizontal patient supporting surface, a longitudinal axis, and a transverse axis, whereby a patient is disposable on the patient supporting surface with its head and feet along the longitudinal axis and shoulders along the transverse axis; a pair of pole pieces disposed adjacent opposite sides of the patient supporting surface for providing a primary magnetic field air gap therebetween parallel to the transverse axis; an adjusting means for adjusting a relative position of the patient supporting surface and the pole pieces; a ferrous member interconnecting the pole pieces, the ferrous member being disposed principally below the patient supporting surface such that the patient is able to be moved freely between the pole pieces and substantial clearance is provided above the patient, the ferrous member including a pair of side members extending from the pole pieces generally parallel to each other and a connecting member that conencts the side members below the patient supporting surface; a magnetic field driver connected with the connecting member for generating a magnetic flux loop through the connecting member, the side members, and the pole pieces to create a primary magnetic field across the air gap generally parallel to the transverse axis, the magnetic flux driver and the connecting member causing a secondary magnetic field in the air gap that bends the primary magnetic field out of parallel to the transverse axis; shimming coils disposed contiguous to the pole pieces for optimizing uniformity of the primary magnetic field in the air gap; a magnetic field correcting means disposed between at least the ferrous member connecting portion and the air gap for shielding the primary magnetic field from the effects of the secondary magnetic fields, whereby magnetic field bending caused by the cross member and magnetic field driver are rendered substantially invisible to the primary magnetic field in the gap; gradient field coils for creating gradients in the primary magnetic field in the gap; a coil assembly disposed adjacent the pole pieces for at least one of (i) transmitting radio frequency signals into the gap to induce resonance and (ii) receiving magnetic resonance signals emanating from resonating dipoles in the gap; and, electronic circuitry for processing the magnetic resonance signals received by the receiver coil into an image representation.