MR image noise: Stochastic and nonstochastic effects

MR image noise was studied using a tissue-like gel phantom. This gel was specifically constructed to exhibit relaxation times and electrical properties similar to those of human tissue. Noise was analyzed by power spectrum analysis on a series of images acquired sequentially in time. This analysis provides for a separation of Gaussian white noise from other random fluctuations. The noise properties obtained with the gel phantom are compared with those obtained with nonphysiologic paramagnetic ion solutions. Results indicate that for the imager studied, the non-Gaussian fluctuations can dominate the noise calculation for some pulse sequences