The diagnostic performance of single-photon emission computed tomography (SPECT) and planar imaging of thallium-201 uptake for the detection of coronary artery disease (CAD) was compared in 79 patients who underwent both dipyridamole thallium-201 scintigraphy and coronary angiography. Clinical subgroups were assigned by severity of CAD, presence of a prior myocardial infarction and the number of narrowed coronary arteries. The overall detection of CAD was 89% for SPECT and 67% for planar (p less than 0.001). For the anterior vascular territory, sensitivities for SPECT and planar imaging were 69 and 44% (p less than 0.01), respectively; for the posterior vascular territory, sensitivities were 80 and 54% (p less than 0.01). Receiver-operating characteristic analysis, using a 5-point evaluation scale, was performed for the anterior and posterior vascular territories. Receiver-operating characteristic curves generated for SPECT and planar studies demonstrated improved diagnostic performance by SPECT in the anterior vascular territory, but showed similar performance in the posterior territory because of lower SPECT specificity despite higher sensitivity at clinically relevant decision thresholds. In each clinical subgroup of patients, the detection of CAD by SPECT was significantly superior to that by planar imaging, regardless of the severity of stenosis or the number of significantly narrowed coronary arteries, or whether a myocardial infarction was present. Thus, SPECT thallium-201 scintigraphy is an important and necessary clinical tool for detecting CAD after dipyridamole infusion.