Absolute phasic blood flow measurement in the brain using digital subtraction angiography.

ABSTRACT

RATIONALE AND OBJECTIVES: In this study, an angiographic method using first-pass distribution analysis was used for quantification of phasic volumetric blood flow. Studies were conducted in an angiographic perfusion phantom and in an animal model (rabbit) after intraarterial injection of contrast material. METHODS: Digital subtraction angiography and first-pass distribution algorithm were used to assess the absolute volumetric flow rates. The method, based on the conservation of contrast material in successive angiographic images, uses the videodensitometric information in the arterial bed. Measurements were made by summing the pixel values in the region of interest, covering the whole perfusion 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 angiographic perfusion phantom and the common carotid artery of the animal models correlated well with validation measurements made using ultrasound flowprobes. The measured (M) and known (K) flow rates in the carotid artery were related by M = 0.87 K + 2.50 mL/minute (r = 0.96, standard error 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 techniques, respectively. Conclusion. Results demonstrate the potential use of the first-pass distribution method in conjunction with digital subtraction angiography for measuring phasic arterial blood flow in vivo.