Previously, these capabilities were limited by the inaccuracies of the gated data acquisition needed to freeze the motion of the heart over several beats. Cardiac imaging, particularly of coronary blood vessels, also requires finer resolution than older MR equipment is capable of. Weber expects that MR will close the resolution gap over the next few years as new imaging techniques become available. Spiral imaging techniques have already proven the key to using CT for imaging cardiac arteries. Increased acquisition speed and resolution result from several advances in MR hardware and software.
Some advances allow higher resolution.
Also contributing to better resolution is the use of enhanced gradients. The small magnets that produce gradients are getting stronger and can be turned on and off more rapidly, speeding up data acquisition. In addition, MRI coils are getting more sensitive, producing a higher ratio of signal to noise, resulting in cleaner images and fewer artifacts. These advances make cardiac imaging less reliant on gating techniques, in which a scan is done by turning the magnet on and off at a particular point in the heart beat over several beats to collect enough data in one position. Converting those data into usable images quickly enough to make MR interactive requires high-speed computer processors and software capable of reliably interpreting huge amounts of data.