METHOD AND DEVICE FOR FREQUENCY ADJUSTMENT OF A MAGNETIC RESONANCE IMAGING APPARATUS USING AN INVERSION PULSE

摘要

In a magnetic resonance (MR) system and method for determining an MR system frequency for a region to be examined that has multiple materials therein, a first frequency spectrum is acquired by the execution of a first RF excitation sequence. A second frequency spectrum for the region is acquired by radiation of an RF inversion pulse and execution of a second RF excitation sequence, at the point in time at which the relaxation curve of one of the materials has a zero-crossing. Subsequently, echo signals excited by the second RF excitation sequence are read out, from which a frequency spectrum is determined. The first frequency spectrum and the second frequency spectrum are compared. On the basis of the comparison, maxima of the first frequency spectrum are allocated to different materials. The system frequency is determined on the basis of the allocation of the maxima.

主权项

1. A method for determining a magnetic resonance (MR) system frequency for operating an MR scanner to obtain raw data from a region to be examined of a subject, said region comprising a plurality of different materials, said method comprising:
operating said MR scanner while the subject is situated therein to acquire a first frequency spectrum from said region by executing a first radio-frequency (RF) excitation sequence; operating said MR scanner to acquire a second frequency spectrum from said region, by executing a second RF excitation sequence at a point in time at which a relaxation curve of magnetization of one of said materials has zero-crossing, and reading out magnetic resonance signals acquired at an echo point in time of said second RF excitation sequence, and determining said second frequency spectrum from the acquired magnetic resonance signals; providing the first and second frequency spectrums to a computer and, in said computer, comparing said first frequency spectrum with said second frequency spectrum, and thereby obtaining a comparison result; in said computer, allocating maxima of said first frequency spectrum to respective different materials, among said plurality of materials, based on said comparison result; and in said computer, determining said system frequency dependent on the allocation of the maxima, and emitting an electronic signal representing said system frequency from said computer.