OBJECTIVETo determine the accuracy of dual-source CT (DSCT) coronary angiography (CAG) for the diagnosis of coronary artery disease (CAD) that induces perfusion defects at myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT), by using SPECT and conventional CAG as the reference standard.

METHODSThirty-five patients with suspected or known CAD underwent both DSCT coronary angiography and MPI (using exercise or adenosine stress-rest protocol) with technetium-99m sestamibi SPECT. All the patients were beta-blockers-naïve before DSCT scan. The DSCT CAG studies were classified as having no stenosis, non-obstructive (< 50% luminal narrowing) stenosis, or obstructive (> or = 50% luminal narrowing) stenosis. MPI examinations were classified as showing normal or abnormal (reversible and/or fixed defects). A comparative regional analysis of coronary stenosis on DSCT versus myocardial perfusion on SPECT was made. In a subset of 20 patients, CAG was performed as a reference standard for CT angiography.

RESULTSOn the basis of the DSCT data, 98.4% of coronary segments were assessable. Twenty-seven branches were classified as having no stenosis, among which 85% had normal MPI. Nine branches showed non-obstructive stenosis and 69 branches showed at least one obstructive lesion. Only 50 (64%) branches with an abnormal DSCT had abnormal MPI; even in branches with obstructive stenosis on DSCT, 23 (33%) still had a normal MPI. By receiver operating characteristic curve analysis, at the optimal cutoff value of 58% stenosis, the sensitivity and specificity of DSCT to detect myocardial perfusion defect as defined by SPECT were 85% and 65%. In the subgroup compared with CAG, the sensitivity and specificity of DSCT to identify obstructive stenosis were 93% and 96%.

CONCLUSIONSDSCT and SPECT provide mutually complementary information on CAD. CT angiography can help rule out functionally relevant CAD, but has poor capability in predicting ischemia. DSCT provides high-quality diagnostic image without heartbeat controlling and has a high accuracy in detecting obstructive stenosis.