Initially, the FA employs approximations of the activity in the LV, the RV and the Myocardium derived from the lung activity. However, after a FA has been performed and the TACs have been calculated, they represent a more accurate information and can be used in a new FA iteration. Therefore, on the Kinetic Modeling page, a new button FA appears as illustrated below.
When it is activated, a dialog window appears which shows the TACs to be used.
If the user confirms with Yes, the FA is repeated with this information. Note that the resulting factor images are in the original orientation and need to be transformed to the short axis orientation again.