How is MRA image acquisition timed?
The arterial phase of MRA can be timed by visualization of the contrast material entering the arterial tree of interest. The alternative is to obtain multiple acquisitions (multiphasic imaging) through the anatomic region of interest after contrast administration. Because MRA does not involve ionizing radiation, there is no penalty in terms of radiation exposure with multiphasic imaging.
Multiphasic imaging is typically used to assess the temporal filling pattern of vascular lesions. This is also utilized when the arteries of interest are confined to an extremity, such as in the hand or calf.
