Motion detection from the raw data in projection reconstruction MR imaging

We present a new quantitative method to determine motion intervals in projection reconstruction (PR) magnetic resonance (MR) imaging. In the first section of this paper, the theoretical concept that formed the basis for the development of the method, is described. It is shown that, in case of PR, the phase difference between the complex means of two consecutive 1D signals equals zero when no motion occurs during the measurement of these signals. On the contrary, when motion does occur, this phase difference becomes large. These conclusions are used to determine the motion intervals in experimentally measured PR data. The motion-detection method that is proposed proves to be able to detect motion intervals with an accuracy of one repetition time, both in the case of long and repetitive motion and in the case of relatively short motion