Coronary artery disease

Coronary artery disease (CAD) is atherosclerotic narrowing of the epicardial coronary arteries, causing a mismatch between myocardial oxygen supply and demand that manifests as angina, ischaemia on stress testing, or myocardial infarction. Nuclear cardiology's role is functional: myocardial perfusion imaging (MPI) with SPECT or PET compares blood flow at rest and under stress (exercise or pharmacologic vasodilation) to localise and size reversible (ischaemic) versus fixed (infarcted or scarred) defects, and to risk-stratify patients for revascularisation versus medical therapy.

SPECT MPI with technetium-99m sestamibi or tetrofosmin, or historically thallium-201, remains the most widely performed test worldwide. PET MPI with rubidium-82, nitrogen-13 ammonia, or since 2024 fluorine-18 flurpiridaz adds absolute myocardial blood flow quantification (mL/min/g) and lower radiation dose per study, at the cost of needing an on-site generator or cyclotron for the shorter-lived tracers. ASNC/SNMMI procedure standards and appropriate use criteria govern tracer choice, dosing and interpretation.

Open questions in practice include how routinely to add absolute flow quantification to standard visual and semi-quantitative reads, and how flurpiridaz's long half-life (which permits exercise stress PET, previously impractical with short-lived PET tracers) will change referral patterns away from SPECT.