Magnetic Resonance angiography (MRA) is introduced

which is a kind of technology of MRI applied in blood flow. MRA shows only the blood flow and suppresses the static tissue. Various aspects about this technology such as potential clinical application

background

methods and pluse sequences are presented. The techniques of MRA have been sorted into two classes. The first class is the time-of-flight methods which use the effets on NMR signal caused by blood flowing in or out of the imaging plane. The second class is the phase contrast methods which rely on motioninduced phase shifts in transverse spin magnetization. On the low-field MRI system (0.15T) made by ourself

a special pulse sequece has been designed and the arterial

veinal and arterial-veinal angiography can be obtained separatly

and the results are satisfatory. The present difficulties in MRA are also presented and discussed.