Noise reduction for T2 derived magnetic resonance images

Calculation of magnetic resonance images composed of signals arising from T2 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 T2 values predominate in regions of low S/N, precluding the routine use of T2 images in diagnostic and quantitative analysis. This study demonstrates that only three spin-echoes signals (TE = 20, 40, and 60 msec) and a simple preprocessing selection criteria are necessary to significantly reduce erroneous T2 values. This simple selection criteria obviates the need to apply a median filter to the T2 image and thus preserve both the high inherent contrast and spatial resolution of the T2 derived image.