EDITORIAL Dynamic perfusionCT:what is normalmyocardial blood flow?

Coronary computed tomography angiography (CTA) is an estab-lished, reliable test for the anatomical diagnosis of obstructive coron-ary artery disease (CAD). However, although coronary CTA provides high sensitivity and a negative predictive value for detecting ≥50 % diameter stenosis, it is limited in its ability to diagnosemyocar-dial ischaemia. Since thediscrepanciesbetweenthe anatomical sever-ity of a lesion and its haemodynamic significance are common, functional evaluation of intermediate stenoses is recommended for therapeutic decisions.1 Adding myocardial CT perfusion (CTP) imaging to CTA provides an opportunity for combined evaluation of coronary anatomy and functional significance of coronary stenosis.2,3 Myocardial CTP imaging is based on the assessment of contrast attenuation in the myocardium, which is proportional to tissue con-centration of iodinated contrast agent. Myocardial CTP imaging ca