Comparison of Dual-Energy Computed Tomography of the Heart with Single Photon Emission Computed Tomography for Assessment of Coronary Artery Stenosis and of the Myocardial Blood Supply

OBJECTIVES: To evaluate the performance of dual-energy computed tomography (DECT) for integrative imaging of the coronary artery morphology and the myocardial blood supply.

METHODS: 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by a single-contrast medium-enhanced, retrospectively electrocardiographic-gated dual-energy CT (DECT) scan with simultaneous acquisition of high and low x-ray spectra. Thirteen patients subsequently underwent invasive coronary angiography (ICA). The DECT data were used to reconstruct anatomic coronary CT angiographic images and to map the myocardial iodine distribution within the left ventricular myocardium. Two independent observers analyzed all DECT studies for stenosis and myocardial iodine defects. A segmental comparison was performed between the stress/rest SPECT perfusion defects and DECT iodine defects and between the ICA and coronary CT angiographic findings for stenosis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were estimated, along with the kappa statistics.

RESULTS: Overall, DECT had 92% sensitivity and 93% specificity, with 93% accuracy for detecting any type of myocardial perfusion defect seen on SPECT. Contrast defects at DECT correctly identified 85 (96%) of 89 fixed and 60 (88%) of 68 reversible myocardial perfusion defects. The interobserver agreement was very good (weighted kappa = 0.87). Compared with ICA, coronary CT angiography had 90% sensitivity, 94% specificity, and 93% accuracy for the detection of >50% stenosis. In

CONCLUSIONS: Our initial experience suggests that DECT, as a single examination, might be promising for the integrative analysis of the coronary artery morphology and the myocardial blood supply and is in good agreement with ICA and SPECT.

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2 Comments

  1. More support for a dedicated dual energy protocol to improve identification of myocardial perfusion defects. Therefore, allowing simultaneous evaluation of coronary stenosis and physiologic consequences.
    While dual energy protocols may improve tissue characterization, the search for myocardial hypo-enhancement should be a routine of any coronary CTA with current scanners.
    Please also see:
    Detection of myocardial infarction by dual-source coronary computed tomography angiography using quantitated myocardial scintigraphy as the reference standard.
    Rubinshtein R, Miller TD, Williamson EE, Kirsch J, Gibbons RJ, Primak AN, McCollough CH, Araoz PA.
    Heart 2009 Sep;95(17):1419-22.
    PMID: 19196731

  2. Just published on JACC; a different approach for the use of DSCT combining stress and rest myocardial perfusion imaging with coronary CT angiography (PMID: 19744616).

    In this study, 33 patients underwent DSCT CTA, a nuclear stress test, and conventional angiography. On a per-vessel basis, CTP alone had a sensitivity of 79% and a specificity of 80% for the detection of stenosis 50%, whereas SPECT myocardial perfusion imaging had a sensitivity of 67% and a specificity of 83%. For the detection of vessels with 50% stenosis with a corresponding SPECT perfusion abnormality, CTP had a sensitivity of 93% and a specificity of 74%. The CTA during adenosine infusion had a per-vessel sensitivity of 96%, specificity of 73% (this is the one concerning result of the study), and negative predictive value of 98% for the detection of stenosis 70%.

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