| 摘要 |
Turbulent fluid flow within a subject is imaged using a magnetic resonance imaging method which is sensitive to non-coherent changes in the magnetic resonance signal intensity and phase. Flow-induced phase shifts are generated in the magnetic resonance signal with a bi-polar magnetic field gradient pulse applied in an arbitrary orientation. Data is acquired in the presence of a uniform flow encoding field gradient applied in an selected direction independent of the bi-polar field gradient pulse. The flow encoding gradient induces a frequency shift in the data which is proportional to position along the direction of the gradient. The spatial distribution of magnetic resonance spins within the flowing fluids along this applied frequency-encoding magnetic field gradient is determined by Fourier transformation. Data acquisition and Fourier transformation are repeated for a plurality of cardiac cycles of the subject and the standard deviation of the magnetic resonance signal at each position along the applied magnetic field gradient is calculated to produce a one-dimensional projection of the random component of the flow-induced phase shift. The steps of data acquisition, Fourier transformation and standard deviation calculation are then repeated for multiple directions of the frequency-encoding magnetic field gradient. A two-dimensional spatial distribution of the non-coherent component of the magnetic resonance signal is then determined by projection reconstruction of the standard deviation projection data sets.
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