Diagnostic Performance of Myocardial Perfusion Imaging for Coronary Artery Disease

Diagnostic Accuracy

• The American Heart Association recommends myocardial perfusion imaging, which demonstrates a sensitivity of 82-91% and specificity of 70-90% for detecting obstructive coronary artery disease, with pharmacological stress slightly outperforming exercise stress 1
• Pharmacological stress achieves higher sensitivity and specificity compared to exercise stress, making it preferable for patients with limited exercise capacity 1

Performance in Specific Populations

• In women, technetium-99m agents with gated SPECT achieve a sensitivity of 87% and specificity of 91% after bias correction, representing substantial improvement over thallium-201 imaging 2
• In diabetic patients, SPECT MPI shows a sensitivity of 87-89% and specificity of 73-75% for detecting angiographically significant CAD 3

Technical Limitations and Considerations

• Balanced ischemia can appear falsely normal, underestimating ischemic burden, particularly in left main or three-vessel disease 1, 4
• Breast tissue artifact affects image quality in women and men with large breasts, though Tc-99m agents and attenuation correction reduce this problem 1, 4
• Obesity degrades diagnostic image quality, though PET maintains higher accuracy in obese patients 1, 4

Comparative Performance of Imaging Modalities

• PET myocardial perfusion imaging achieves slightly higher sensitivity than SPECT, particularly in women and obese patients, due to superior spatial resolution and photon attenuation correction 1, 4
• Combining SPECT with coronary CT angiography dramatically improves diagnostic accuracy to sensitivity 96% and specificity 95% 3

Prognostic Value

• Normal stress SPECT predicts excellent outcomes, with an annual cardiac event rate of only 1% in patients with intermediate to high pretest probability of CAD 2, 3
• Abnormal perfusion studies stratify risk proportionally to defect extent and severity, with three-year survival declining from 99% (no ischemia) to 85% (three-vessel territory ischemia) 2