A SIMPLE METHOD FOR INVESTIGATING THE EFFECTS OF NONUNIFORMITY OF RADIOFREQUENCY TRANSMISSION AND RADIOFREQUENCY RECEPTION IN MRI

Inhomogeneity of the transmitted or received B-1 field leads to intens ity variations in MR images and spatial dependence in apparent concent ration in MR spectra. We describe a simple method for investigating su ch variations. The transmitted B-1 field can be measured both in vivo and in vitro which allows investigation of sample dependent effects th at can not be measured on phantoms. For homogeneous regions the method also allows the received B-1 field to be measured both in vivo and in vitro. Our method uses only a standard spin echo pulse sequence and s imple region of interest analysis and should be implementable on any c ommercial scanner. The method is demonstrated using a variety of trans mission and reception radiofrequency coils both in vivo and in vitro.