Abstract 13023: Incremental Diagnostic Accuracy of Hybrid Single Photon Emission Computed Tomography Coronary Angiography in Suspected Coronary Artery Disease

Abstract

Background: Single-photon emission computed tomography (SPECT) and computed tomography coronary angiography (CTCA) are often undertaken independently in patients with suspected coronary artery disease (CAD). Hypothesis: We assessed the hypothesis that hybrid SPECT/CTCA imaging results in higher diagnostic accuracy than either method alone, allowing some false positives to be ruled out in the non-invasive testing phase. Methods: A total of 129 vessels (43 patients) were screened by SPECT with cadmium-zinc-telluride semiconductors and CTCA with a 256-detector row CT of the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex (LCX) segments. Patients who were diagnosed with myocardial ischemia then went on to undertake CAG. A diameter stenosis > 50% and any non-diagnostic segment in CTCA were considered abnormal. CAG results were classified as positive for stenosis when either a diameter stenosis was over 75% or fractional flow reserve was under 0.8. These were then compared to an image fusion of SPECT and CTCA data sets performed on a dedicated workstation. The results were categorised as a match or a mismatch (same as or different to the CAG, respectively). Results: Matched findings at SPECT, CTCA, and hybrid imaging were found in vessels of 75%, 67%, and 92%, respectively. Compared to the individual diagnostic performance of SPECT or CTCA in detecting significant CAD, hybrid imaging exhibited greater results in all of sensitivity, specificity, and accuracy (Fig 1). Segmental reclassification of perfusion abnormalities by hybrid imaging occurred at 10% for LAD, 56% for LCX, and 5% for RCA. Moreover, hybrid imaging allowed for accurate diagnosis of 22 vessels with severe calcification which CTCA alone could hardly evaluate correctly (Fig 2). Conclusions: Hybrid imaging showed higher diagnostic accuracy compared to single modalities, enabling physicians to make better decisions about the necessity for invasive CAG procedure.