ANGIOGRAPHIC IMAGING WITH 2D RF PULSES

Magnetic resonance angiography (MRA) was performed by using RF pulses designed to excite a limited spatial extent in two orthogonal directio ns. The restriction in the second spatial dimension can be used to inc rease inflow enhancement and to improve small field-of-view imaging. A rectangular excitation was produced with an ''echo-planar'' k-space t rajectory and a sine-modulated RF waveform. In vivo images have demons trated that vessels are more clearly delineated with the two-dimension al excitation. Aliasing artifacts in smalt field-of-view imaging are s ignificantly reduced, although in some cases complete elimination is n ot possible due to the nature of the gradient trajectory.