Absolute volumetric blood flow measurements using dual-energy digital subtraction angiography

In recent years, as a solution to the well-documented problems associated with visual interpretation of coronary arteriograms, more physiologic means of assessing coronary artery stenosis are being investigated. Absolute arterial blood flow assessed as a function of time can be a valuable aid in the analysis of functional significance of arterial lesions and obstructions. An absolute volumetric blood flow measurement technique using a motion immune dual-energy subtraction technique is being investigated, where the kVp and filtration are switched at 30 Hz. The low- and high-energy images are corrected for scatter and veiling glare before subtraction. In this technique, the absolute arterial blood flow is calculated by combining the videodensitometric analysis of spatial and temporal aspects concerning the contrast propagation through the arterial bed using tissue suppressed energy subtracted images. The blood flow measurement technique was validated using a pulsatile pump and a flow chamber imaged over a Humanoid chest phantom. A 20-MHz Doppler flow probe was used to validate the measurement of phasic volumetric blood flow. The measured (M) and known (K) mean blood flow for the entrance vessel technique and the videodensitometric calibration technique were related by M = 1.14K - 0.12 ml/s (r2 = 0.98) and M = 1.12K - 0.23 ml/s (r2 = 0.90), respectively. The results indicate that phasic volumetric blood flow can be measured using a CCD camera in conjunction with real time dual-energy subtraction.