Comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi SPECT imaging (perfusion and ECG-gated SPECT) in detecting coronary artery disease in women.

OBJECTIVES: This prospective study was conducted in 115 women to directly compare the sensitivity and specificity of thallium-201 (Tl-201), technetium-99m (Tc-99m) sestamibi perfusion and Tc-99m sestamibi electrocardiographic (ECG)-gated single-photon emission computed tomographic (SPECT) studies for detection of coronary artery disease (CAD).

BACKGROUND: Data on the comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi perfusion imaging for the detection of CAD, specifically in women, are very limited.

METHODS: Eighty-five patients with suspected CAD, scheduled for coronary angiography, and 30 volunteers with a pretest likelihood of < or = 5% for CAD were evaluated. Within 1 week, each patient underwent Tl-201 and Tc-99m sestamibi SPECT imaging procedures (both perfusion and gated SPECT imaging). Treadmill stress testing was used in 78 patients and dipyridamole in the remaining 37 patients. All images were interpreted by three observers in a blinded manner (consensus reading). Technetium-99m sestamibi SPECT studies were read without and then with ECG gating. Technetium-99m sestamibi gated SPECT studies were used to differentiate scar tissue from soft tissue attenuation artifact.

RESULTS: The overall sensitivities for detecting > or = 50% and > or = 70% stenoses were 75.0% and 84.3%, respectively, for Tl-201, and 71.9% and 80.4%, respectively, for Tc-99m sestamibi perfusion studies (p = 0.48). The specificity for lesions > or = 50% was 61.9% for Tl-201 and 85.7% for Tc-99m sestamibi perfusion (p = 0.07), whereas for lesions > or = 70% it was 58.8% for Tl-201 and 82.4% for Tc-99m sestamibi perfusion (p = 0.01). When the 34 patients with a normal coronary angiogram were added to the group of 30 normal volunteers, the "specificity" for lesions > or = 70% was 67.2% for Tl-201, 84.4% for Tc-99m sestamibi SPECT perfusion (p = 0.02) and 92.2% for Tc-99m sestamibi gated SPECT (p = 0.0004).

CONCLUSIONS: Both Tl-201 SPECT and Tc-99m sestamibi SPECT perfusion studies had a similar sensitivity for the detection of CAD in women. However, Tc-99m sestamibi SPECT perfusion imaging shows a significantly better specificity, which is further enhanced by the use of ECG gating.