NUCLEAR MAGNETIC RESONANCE IMAGING

摘要

An object (50) incorporating stationary matter and moving matter such as blood is imaged by applying a series of NMR signal generation suquences. A first sequence (C1, C10, C100, C101) generates an NMR signal and a second sequence (C2, C20, C200, C202) generates an NMR signal of opposite phase. The second sequence may include an RF excitation signal (78) of opposite phase to the corresponding RF excitation signal (78) in the first sequence. NMR signals resulting from these two sequences are added to form composite signals. Components of the NMR signals produced by stationary matter in the object cancel one another during addition because of the oppositely phased excitation signals, whereas components of the NMR signals produced by the moving matter or blood are affected differently by velocity and hence do not cancel one another. Different velocity effects in the two sequences may be created by synchronizing the sequences to different phases of a velocity waveform (56) of the moving matter.