Noise reduction for T 2 derived magnetic resonance images

Abstract

Calculation of magnetic resonance images composed of signals arising from T 2 and proton densities can be performed using a least squares fitting procedure from three or four multiple spin-echo images. This procedure works well in regions of high signal-to-noise (S/N) in the multiple spin-echoes. Erroneous T 2 values predominate in regions of low S/N, precluding the routine use of T 2 images in diagnostic and quantitative analysis. This study demonstrates that only three spin-echoes signals (T E = 20, 40, and 60 msec) and a simple preprocessing selection criteria are necessary to significantly reduce erroneous T 2 values. This simple selection criteria obviates the need to apply a median filter to the T 2 image and thus preserve both the high inherent contrast and spatial resolution of the T 2 derived image.