CCTA is excellent for defining the exact course and origins of coronary arteries. Several benign variations are routinely encountered — knowing them prevents over-calling pathology.
Present in ~ 15% of the population. Occurs when the left main coronary artery trifurcates, giving rise to a third vessel (the ramus intermedius) that travels between the LAD and LCx.
The LAD and LCx arise from completely separate ostia directly from the left coronary sinus.
The coronary ostium arises high above the sinotubular junction — usually inconsequential but worth noting for procedural planning.
The conus branch typically arises as the first branch of the RCA, but can occasionally arise from a separate ostium directly from the right sinus of Valsalva. The SA nodal branch usually arises from the proximal RCA, but frequently arises from the LCx instead.
A segment of an epicardial artery (usually the LAD) temporarily dives deep into the myocardium. Full article: Myocardial bridge.