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US 7,480,527 B2Granted
Magnetic resonance imaging method and apparatus with non-selective excitation of the examination subject
AssigneeSiemens Aktiengesellschaft
InventorsVibhas Deshpande, Gerhard Laub
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Abstract
In a magnetic resonance imaging apparatus and a method for operating the apparatus, a trueFISP sequence is used, but is modified to employ non-selective, rectangular radio frequency pulses. The use of non-selective excitation pulses reduces the sensitivity to off-resonance and allows excitation to be achieved in a shorter time compared to selective excitation, thereby shortening the time between echoes and minimizing slice profile issues.
Claims18
A method for operating a magnetic resonance (MR) apparatus to obtain MR image data, comprising the steps of:
- emitting a trueFISP MR data acquisition sequence and in said trueFISP MR data acquisition sequence, from a radio frequency resonator, emitting a plurality of only non-selective, rectangular radio frequency excitation pulses into an examination subject that excite nuclear spins in the examination subject;
- between successive ones of said radio frequency excitation pulses, emitting a phase encoding magnetic gradient from a gradient coil system in a first direction to encode said examination subject;
- also between said successive ones of said radio frequency excitation pulses, emitting a readout magnetic gradient from said gradient coil system in a second direction and, durinq said readout magnetic gradient, acquiring MR signals produced by said nuclear spins;
- and
- also between said successive ones of said radio frequency excitation pulses, emitting a refocusing magnetic gradient from said gradient coil system in each of said first and second directions to refocus transverse magnetization in the examination subject in said first and second directions.
2 more elements
A magnetic resonance (MR) imaging apparatus comprising:
- an (MR) scanner configured to receive an examination subject therein, comprising a basic field magnet, a radio frequency resonator, and a gradient coil system;
- and
- a computerized control arrangement connected to said MR scanner that operates said MR scanner to emit a trueFISP MR data acquisition sequence and said control arrangement in said trueFISP sequence causing said radio frequency resonator to emit a plurality of only non-selective, rectangular radio frequency excitation pulses into the examination subject that excite nuclear spins in the examination subject, and causing said gradient coil system, between successive ones of said radio frequency excitation pulses, to emit a phase encoding magnetic gradient in a first direction to encode the examination subject and to emit a readout magnetic gradient in a second direction during which magnetic resonance signals produced by said nuclear spins are acquired, and to emit a refocusing magnetic gradient in each of said first and second directions to refocus transverse magnetization in the examination subject in said first and second directions.
Dependencies are inferred from the claim text.