1. A magnetic resonance imaging system for imaging an artery of a patient using an administered magnetic resonance contrast agent, the magnetic resonance imaging system comprising: a monitor unit to allow an operator to visually observe an arrival of the contrast agent in an artery of interest and determine when to start 3D gradient echo imaging; and a magnetic resonance imaging unit to collect image data of a 3D gradient echo imaging sequence to image the artery, wherein the magnetic resonance imaging unit, in response to an input from the operator after arrival of the contrast agent in the artery of interest and during the arterial phase of contrast enhancement, collects image data which is representative of a central portion of k-space near the beginning of the 3D gradient echo imaging sequence, and wherein the magnetic resonance imaging unit further collects post-contrast image data in which there is enhancement of both arteries and veins.