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Quantitation of absolute regional myocardial perfusion using cine computed tomography
R M Weiss1, E A Otoadese, M P Noel
1Department of Internal Medicine, University of Iowa, Iowa City 52242.
Objectives:
The purpose of this study was to develop and test a method for quantitation of regional myocardial perfusion using cine computed tomography.
Background:
Cine computed tomography is a relatively new cardiac imaging technique with excellent temporal and spatial resolution. Application of this technique to the study of human coronary circulation could substantially broaden our knowledge of human cardiac pathophysiology. This goal has been previously approached with some success. However, no method to date has shown validated accuracy of regional perfusion measurements over the entire range of physiologically important flow states.
Methods:
Eight anesthetized dogs underwent thoracotomy for instrumentation. They were then studied during baseline flow conditions, after coronary vasodilation with intravenous dipyridamole and after coronary stenosis or occlusion. Regional myocardial perfusion was assessed by cine computed tomography using a method that includes estimates for myocardial blood volume and rate of myocardial enhancement after an aortic root contrast medium infusion. Measurements made nearly simultaneously by the radioactive microsphere method served as a reference standard.
Results:
A total of 32 perfusion conditions were studied with a range of 4 to 593 ml/min per 100 g. There was reasonable agreement between the two methods of measurement throughout the whole range of perfusion states: r = 0.97, regression slope 0.99, intercept 2 ml/min per 100 g. In zones not subserved by a stenosed or occluded artery, cine computed tomography accurately depicted perfusion homogeneity with a coefficient of variation of 13 +/- 1% (mean +/- SE) versus 11 +/- 1% for the microsphere method (p = NS).
Conclusions:
Cine computed tomography is capable of providing accurate, quantitative assessment of regional myocardial perfusion over a broad range of perfusion states. This method, if extended to the study of humans, could enhance the understanding of disorders of the coronary circulation in human cardiovascular disease states.