Method for avoiding over-convolutions in the phase coding direction in nuclear magnetic resonance tomography
AssigneeSiemens Aktiengesellschaft
InventorAndreas Alzner
Life of this patent
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Abstract
In a method and magnetic tomography apparatus wherein over-convolutions in the phase coding direction in magnetic resonance tomography are avoided, orthogonal slices are measured as overview presentations (localizers) in a first step and slices for the following measurement series are then determined. Overlapping phases and the magnitude of the appertaining signal are calculated and a warning is emitted when this over-convoluted signal exceeds a reference value. A selection possibility is then offered for reducing the phase coding steps and enlarging the field of view and, if selected, the phase coding step width is automatically reduced.
Claims8
A method for avoiding over-convolutions in a phase coding direction in magnetic resonance tomography, comprising the steps of:
- (a) obtaining magnetic resonance data for an overview presentation selected from the group consisting of data for three orthogonal slices of a subject and data for a three-dimensional volume of a subject;
- (b) from said overview presentation, determining slices for a subsequent magnetic resonance measurement sequence which includes phase coding produced by changing a phase coding gradient in phase coding steps each having a step width, said sequence having a field of view associated therewith;
- (c) from the selected slices of said measurement sequence, calculating, in a computer, overlapping phases and a magnitude of a signal produced by said overlapping phases;
- (d) emitting a warning indicating over-convolution if said signal exceeds a reference value;
- (e) together with said warning, offering a selection to a user for reducing said phase coding step width to enlarge said field of view;
- and
- (f) automatically reducing said phase coding step width if said selection is selected.
A magnetic resonance tomography system, comprising
- a magnetic resonance scanner including a control computer which controls said scanner to obtain magnetic resonance data for an overview presentation selected from the group consisting of data for three orthogonal slices of a subject and data for a three-dimensional volume of a subject;
- said control computer, from said overview presentation, determining slices for a subsequent magnetic resonance measurement sequence by said scanner which includes phase coding produced by changing a phase coding gradient in phase coding steps each having a step width, said sequence having a field of view associated therewith;
- from the selected slices of said measurement sequence, said control computer calculating overlapping phases and a magnitude of a signal produced by said overlapping phases;
- an operator console connected to said control computer, said control computer causing a warning to be emitted at said console, and indicating over-convolution if said signal exceeds a reference value, and together with said warning, to offer a selection to a user for reducing said phase coding step width to enlarge said field of view;
- and
- said control computer automatically reducing said phase coding step width if said selection is selected via said console.
Dependencies are inferred from the claim text.