Coronary MR angiography is a promising technique for coronary artery imaging in 3D, as it is non-invasive, non-irradiating and does not necessarily require injecting a contrast agent.
However numerous technical difficulties need to be overcome, and no validated method or sequence exists to date.
Therefore we will focus on the constraints involved in coronary MR angiography techniques, and the solutions currently available.

 

Technical challenges

The coronary vascular system is small in caliber and sinuous, relatively spread out in space, with the presence of pericardial fat on contact. Coronary MR angiography thus has to establish a compromise between acquisition time, spatial resolution, ratio of contrast versus noise and the correction of cardiac and respiratory motion.

 

State of the art
  Speed Cardiac motion Respiratory motion Spatial resolution Contrast Signal/Noise
High field Incr.
Parallel acquisition Incr.
Segmented / spiral k-space filling Incr.
Real time imaging Incr. X X Decr.
Target study of coronary axis routes Incr.
Global 3D study of the entire heart Decr. Incr. Incr.
Cardiac synchro in mid-diastole Decr. X
Breath-hold X
Echo navigator Decr. X
Gradient echo with balanced gradients Incr. Incr.
Contrast agents with vascular remanence X
Dark blood imaging X
T2 pre-impulsion Incr.
Fat Saturation Incr.

 

Potential clinical applications
  • Coronary stenosis
  • Coronary bypass
  • Imaging of plaque and the artery walls