Quantitative myocardial CT perfusion: a pictorial review and the current state of technology development

Coronary artery disease (CAD) is one of the leading causes of morbidity and mortality, and is associated with substantial and increasing resource burden. A combined physiologic and anatomic assessment may improve identification of patients with CAD who would benefit from revascularization and reduce unnecessary diagnostic and interventional procedures. Cardiovascular computed tomography (CT) has the potential to provide a comprehensive evaluation of CAD in a single setting. Although coronary CT angiography has been widely implemented for clinical use, the application of myocardial CT perfusion (CTP) has been relatively restricted because of a few limitations, such as beam hardening and the high radiation dose delivered. In this article, we first review the fundamental basis of the qualitative, semiquantitative, and quantitative techniques for myocardial CTP and discussed the strength and weakness of each approach. Beam-hardening correction for myocardial CTP with image-based method and dual-energy CT are then discussed with example cases demonstrating the effectiveness of each method. Initial experiences suggest both techniques can reduce beam-hardening artifact to a satisfactory extent. An overview on dose reduction technologies, such as prospective ECG triggering and iterative reconstruction for myocardial CTP, is also provided. Preclinical studies suggest it is feasible to perform low-dose quantitative myocardial CTP without affecting perfusion measurement. Finally, the impact of scan length on myocardial CTP is addressed.