• Coronary artery disease
• coronary vasomotion
• CT scanning
• endogenous fibrinolysis
• endothelium
• intravascular ultrasound
• MRI
• platelet activation

The assessment of coronary artery disease has advanced beyond the mere quantification of luminal stenosis to include mult-modality imaging that is capable of assessing the extent and functional significance of a stenosis and the possible vulnerability of a lesion. CT coronary angiography is now an established technique for the investigation of coronary artery disease, and the potential for CT myocardial perfusion imaging is being established. However, the optimal methods for CT myocardial perfusion image acquisition, image analysis and quantification have yet to be defined.

CT coronary angiography with modern imaging techniques has a sensitivity approaching 100%.1 However, the specificity of this technique is reduced by its propensity to overestimate heavily calcified stenosis.2 For such patients, additional imaging procedures may be required to assess adequately the significance of their coronary artery disease. In addition, it has been established that the selection of patients for coronary revascularisation is best performed by identifying inducible myocardial ischaemia.3 It would therefore be a major advance if CT myocardial perfusion imaging could be performed in patients with coronary artery disease of uncertain severity and as a means of planning coronary revascularisation, especially as an optional follow-on procedure to CT coronary angiography.

Previous research studies have compared CT myocardial perfusion imaging with other functional imaging techniques such as MRI, radionucleotide perfusion imaging and fractional flow reserve measurements made during invasive coronary angiography, and have identified sensitivities of 83–91% and specificities of 72–98%.4 At present, beam hardening, motion and reconstruction artifacts are important limitations for CT myocardial perfusion imaging. Nevertheless, CT myocardial perfusion imaging is additive to CT coronary angiography5 and useful in the assessment of patients with coronary artery stents.6 However, the primary method used in …