A method for reducing motion induced errors in T2-weighted magnetic resonance imaging

It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a way which greatly reduces the severity of such errors. The method was tested on both a moving phantom and a living rabbit. The pulsing of the scanner was gated in synchrony to the motion of the phantom; two pulses per mechanical cycle were used to create a special situation which served to verify the validity of a theoretical analysis of the loss of signal with echo time. Under such conditions it was shown that the conventional method led to a progressive loss of signal with increasing TE while the new method gave a pure exponential decay of signal in accordance with the known T2 of the sample. When either the phantom or the animal was scanned without gating, the new pulse sequence showed far less artifacts attributable to motion. The potential application of the technique to improved quantitative imaging of the abdomen in clinical situations is discussed.