Dynamic contrast-enhanced magnetic resonance angiography of the thoracic vessels: an intraindividual comparison of different k-space acquisition strategies.

OBJECTIVES

The combination of parallel acquisition (generalized autocalibrating partially parallel acquisitions) and time-resolved three-dimensional (3D) view-sharing techniques is a promising tool for dynamic contrast-enhanced 3D-magnetic resonance angiography (MRA). We evaluated the influence of different k-space acquisition strategies on image quality for a recently developed time-resolved echo-shared angiographic technique during a contrast-enhanced 3D-MRA of the thoracic vessels.

MATERIALS AND METHODS

In 20 patients (16 men, 4 women; range, 28-75 years), 2 dynamic MRA protocols with different k-space acquisition strategies were performed on a 1.5-T whole-body scanner (MAGNETOM Avanto, Siemens AG, Erlangen, Germany) during injection of 5 mL (flow-rate, 3 mL/s) gadobutrol. For protocol 1, the central-region which was updated with every cycle included 20% of the entire k-space (protocol 2: 10%), the peripheral-region was undersampled by a factor of 10 (protocol 2: 5%). Image quality and details were compared visually. Signal-to-noise ratio and sharpness of vessel borders were estimated.

RESULTS

Morphologic and functional assessment of the pulmonary arteries and the aorta was significantly improved for protocol 1. The sharpness of vessel borders (3.3 mm vs. 4.1 mm; P = 0.001), image quality, and the visibility of image details were significantly improved for protocol 1 compared with protocol 2.

CONCLUSION

The size of the central region that is updated for every frame seems to be more crucial for image quality of echo-shared angiographic techniques than the sampling density in the periphery of the k-space.