Quantification of Fractional Flow Reserve Using Angiographic Image Data

Abstract

AbstractCoronary arteriography is the standard method for determination of coronary anatomy and assessment of atherosclerosis. However, there are well known limitations to the use of visual estimation to assess the severity of coronary artery disease. These limitations include the large intraobserver and interobserver variability that result from subjective visual grading of coronary stenotic lesions. This is especially true in the case of an intermediate coronary lesion (30%-70% diameter stenosis), where coronary arteriography is very limited in distinguishing ischemia-producing intermediate coronary lesions from non-ischemia-producing ones. Due to the major limitations of standard coronary arteriography, a method for functional measure of stenosis severity such as measurement of fractional flow reserve (FFR) using angiographic image data is desirable. The FFR measurement would provide valuable functional information in addition to the anatomical data obtained during routine coronary arteriography. It is possible to estimate FFR by combining the first pass distribution algorithm for flow with regional lumen volume measurement technique. The study was carried out in anesthetized, closed-chest swine using angioplasty balloon catheters to produce partial occlusion. Angiography based FFR was calculated from an angiographically measured ratio of coronary blood flow to arterial lumen volume. Pressure based FFR was measured from a ratio of distal coronary pressure to aortic pressure. Pressure-wire measurements of FFR (FFRp) correlated linearly with angiographic volume-derived measurements of FFR (FFRv) according to the equation FFRv = 0.50 FFRp + 0.47 where the correlation coefficient and standard error of estimate were 0.90 and 0.05, respectively. In conclusion the results indicate that angiographic FFR can potentially provide an assessment of the physiological severity of a coronary stenosis during routine diagnostic cardiac catheterization without a need to cross a stenosis with a pressure-wire. Therefore, angiographic images can potentially be used for both anatomical and physiological assessment of coronary artery disease.KeywordsAngiographyblood flowblood volumeregional blood flowstenosis