ABSOLUTE PHASIC BLOOD-FLOW MEASUREMENT IN THE BRAIN USING DIGITAL SUBTRACTION ANGIOGRAPHY

RATIONALE AND OBJECTIVES. In this study, an angiographic method using first-pass distribution analysis was used for quantification of phasic volumetric blood now. Studies were conducted in an angiographic perfu sion phantom and in an animal model (rabbit) after intraarterial injec tion of contrast material. METHODS. Digital subtraction angiography an d first-pass distribution algorithm were used to assess the absolute v olumetric flow rates. The method, based on the conservation of contras t material in successive angiographic images, uses the videodensitomet ric information in the arterial bed. Measurements were made by summing the pixel values in the region of interest, covering the whole perfus ion bed. A contrast pass curve was generated for a sequence of images to obtain instantaneous volumetric flow rates. RESULTS. Instantaneous and mean absolute volumetric flow measurements made in the angiographi c perfusion phantom and the common carotid artery of the animal models correlated well with validation measurements made using ultrasound fl owprobes. The measured (M) and known (K) flow rates in the carotid art ery were related by M = 0.87 K + 2.50 mL/minute (r = 0.96, standard er ror of the estimate = 3.79 mL/minute, n = 25) and M = 0.92 K - 1.00 mL /minute (r = 0.98, standard error of the estimate = 4.04 mL/minute, n = 38) using the videodensitometric and entrance vessel calibration tec hniques, respectively. CONCLUSION. Results demonstrate the potential u se of the first-pass distribution method in conjunction with digital s ubtraction angiography for measuring phasic arterial blood flow in viv o.