Rest-stress acquisition should be the protocol of choice in dual-energy (DE) CT for the assessment of the myocardial blood supply, according to a study published in the March issue of Radiology.

Myocardial perfusion is often assessed by single photon emission computed tomography (SPECT) and coronary CT angiography. DE CT acquisitions have been shown to offer easy recognizance of perfusion defects and late enhancement. Lead author Felix G. Meinel, MD, of the Medical University of South Carolina in Charleston, and colleagues compared the relative contributions of rest, stress, and delayed CT acquisitions with the accuracy of DE CT for the assessment of myocardial blood supply.

Fifty-five consecutive patients who were referred for cardiac SPECT and suspected of having coronary artery disease were prospectively enrolled in the study. DE CT studies were obtained during adenosine stress, at rest, and after a six minute delay. After analyses and calculations, 714 segments were considered normal at SPECT. Fixed perfusion defects were seen in 192 segments and 29 exhibited reversible perfusion deficits.

Rest-only DE CT sensitivity was 92 percent, and specificity was 98 percent. Stress-only, rest-stress, stress and delayed, the combination of all three had a sensitivity of 99 percent and a specificity of 97 percent. Of the 29 segments with reversible perfusion deficits at SPECT, 13 were misclassified by using rest-stress DE CT as fixed perfusion deficits. With stress DE CT plus delayed acquisition, 13 of 192 segments with fixed perfusion deficits at SPECT were misclassified as reversible.

“Because reversible perfusion defects at SPECT are frequently detected at rest DE CT, with rest-stress DE CT, one classifies as fixed almost one-half of defects that are reversible at SPECT. Radiologists and clinicians need to be aware of this incongruence when they interpret DE CT myocardial perfusion studies,” wrote Meinel and colleagues.