Correlation of myocardial perfusion scintigraphy and coronary angiography

Discrepancy in findings of coronary angiography and myocardial perfusion-SPECT mostly reflect the hemodynamic effect of the pathological coronary morphology rather than misinterpretation by welltrained nuclear medicine physicians. Thus, perfusion scintigraphy gives a valuable completion of the angiographic findings. Consequently, forecast of coronary stenoses loses importance. The intention of cardiovascular medicine focuses more and more on functional statements. The detection of ischemia is not enough for correlated evaluation of SPECT/PET and coronary angiography. At least, assignment of perfusion defects and vascular territories is necessary. Quantitative evaluation and display of bull's eye are helpful and superior to visual interpretation. Due to the variability of the coronary vascular tree, assignment of angiographic and scintigraphic findings may sometimes remain ambiguous. Moreover, in patients with multivessel disease the detection of less stenosed vessels can be hidden if the stress tolerance is limited by the most severe stenosis. Other factors like morphology, length, and location of a stenosis, collaterals and endothelial dysfunction may also modify myocardial perfusion. Thus 'sensitivity' and 'specificity' of assignment of ischemia to a vascular territory ranges between 62% and 86%. With respect to a high-quality standard of the examinations and to the methodical limitations, head to head comparison of scintigraphic and angiographic images enable evaluation of the hemodynamic consequences of stenoses of a distinct coronary artery. The discrepancy of scintigraphic and angiographic findings in particular can lead to more reliable conclusions than the single examination does with direct impact on decision-making regarding medical or invasive therapy, complete or partial revascularization, and the selection of the vessel which has to be revascularized. Correlation of scintigraphy and angiography enables an individual planning of the therapy procedures with respect to distinct coronary arteries. Current developments forces on 3D-image fusion of SPECT/PET and coronary vascular tree with the intention of a more precise assignment of the two examination modalities. Compared to conventional study evaluation, 3D-fusion image improves reliability of the assignment of scintigraphic and angiographic findings. (orig.)