Scan Abort Threshold

The Scan Abort Threshold User CV is available with 3DCINE-SPGR and FIESTA and 4DFLOW. It is a mechanism to prevent an endless scan due to too many arrhythmic cycles or loss of cardiac triggering and thus it sets the tolerance of the acquisition to arrhythmia rejections. The Scan Abort Threshold does not affect image quality and may prevent excessively long scan times.

Set the Arrhythmia Check User CV to 1 = On.

Consider the following information when selecting the Scan Abort Threshold value.

• Observe the patient’s baseline ECG signal in the magnet. Determine the number of arrhythmias and the number of good R-R intervals and use the ratio of bad-beats : total beats +10% for the abort threshold with a minimum of 50%.
  • For example, if the patient demonstrates 4 good heart beats followed by 6 arrhythmic heartbeats : 6/(4+6) = 0.6 or 60%. Add 10% and set the Scan Abort Limit to 70. Note that the default setting of 50% is equivalent to 5 good beats followed by 5 arrhythmic beats – which is pretty high and thus, should accommodate most patient scans.
• If the patient has lots of arrhythmic heartbeats and the value is too low, the scan may abort.
• The Scan Abort Threshold sets the upper limit for attempting to complete the scan. There is no penalty for setting the Scan Abort Threshold too high; however, If the patient is moving or there are other fixable sources of erroneous heartbeats, a high value allows the scan duration to be longer than necessary.