Patent ID: 6812698
Filing Date: 2004-11-02
Classification: G01R

Abstract:
A spin excitation method for exciting spins within an object to be imaged by a pulse sequence containing RF pulses having SLR waveforms, said method comprising the steps of:obtaining parameters relevant to imaging including type of pulse sequence, repetition time, echo time, number of echoes, field of view, and image matrix size, and number of slices; calculating from said parameters a predicted SAR of said object to be imaged in executing said pulse sequence; comparing said predicted SAR with a predetermined limit of a standard SAR; and adjusting at least one of the following characteristics of the RF pulses; (a) modifying the SLR pulse waveform to be a sinc pulse waveform or a filtered pulse waveform; (b) changing the pulse width of said RF pulse while leaving the SLR waveform otherwise unmodified; (c) changing the number of RF pulses; and (d) a combination of the foregoing characteristics, to control the predicted SAR to be within said predetermined limit without reducing the number of slices during a repetition time period.