Fast spin echo and fast gradient echo MRI with low acoustic noise.
It has been shown previously that a significant reduction of the acoustic noise in standard, slow magnetic resonance imaging (MRI) sequences is achieved when the gradient pulses have long sinusoidal ramps. An improvement of this method is now presented for fast gradient echo (FLASH) and fast spin echo (RARE) sequences. The new strategy consists of using a sinusoidal readout pulse with no plateau and extending the phase encoding pulses to the entire readout period. The distribution of k-space samples is no longer equidistant, and images have to be reconstructed with gridding. A reduction of the acoustic noise by 20-40 dBA was obtained with respect to standard sequences installed by the scanner manufacturer, which is 10-20 dBA better than that with the previously proposed method of sinusoidal ramps. J. Magn. Reson. Imaging 2001;13:960-966.
Hennel
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Commissariat à l'Energie Atomique (CEA), Service Hospitalier Frédéric Joliot (SHFJ), 91401 Orsay, France. hennel@shfj.cea.fr
D017352:Echo-Planar Imaging; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D009622:Noise / Q000517:prevention & control; D012984:Software; D013018:Sound Spectrography