(a) Time intensity curve (bottom modulated curve), decomposed into the wash-in/wash-out component (bottom smooth curve), and the contrast wave component (top curve). (b) Propagation of the contrast wave.
Construction of the contrast wave map. The wave map describes how the contrast pattern is distributed along the arterial axis at a given time index, and is used to determine the motion of the contrast using the optical flow principle. (a) 3DRA. (b) Projection of 3D vessel axis on 2D image. (c) Contrast wave map. The contrast wave map contain the DSA intensities along the projected centerline over time.
Experimental setup comprising a steady pump, a pulsatile pump, an electromagnetic flow meter, and the circulating circuit. Both phantoms were used in this setup.
Steady pump (left) and pulsatile pump (right).
3DRA reconstruction of the cerebral vessel phantom (left), and the two views that were used for measurements (middle and right).
Volume flow estimation using Doppler recordings. (a) Doppler trace and maximum velocity curve. (b) Volume flow curve using the Womersley model.
Flow phantom experiment: (a) Contrast wave map as a function of time (x) and position along the arterial axis (y). Darker intensities correspond to lower contrast medium densities. (b) Flow curves from flow meter and x-ray technique, aligned with the contrast wave map. When injecting contrast into an artery, blood and contrast medium mix proportionally to their respective flow rates. Therefore, high blood flow values lead to lower contrast medium concentrations (darker), and vice versa.
X-ray and flow meter measurement fitting for fr = 50 Hz, L = 30 mm.
Regression slope coefficients with 95% CIs obtained regression of x-ray flow measurements on reference flow meter values. Left: Slopes varying with the frame rate for a fixed vessel length of 30 mm. Right: Slopes varying with the vessel length for a fixed frame rate of 50 Hz.
Flow curves measured with decreasing frame rates.
Gold standard delivered by the flow meter (x-axis) versus the flow measurements using the proposed method (y-axis). Triangles represent the measurements from view 1 and the diamonds the measurements from view 2. The diagonal line indicates the ideal match.
X-ray and Doppler flow curves for three exemplary patient cases. For each line the average arterial flow is reported.
DSA acquisitions of the three presented patients. Left: patient1, middle: patient 2, right: patient 3.
Experimental conditions and flow estimations during in vitro experiments on the straight phantom.
Regression analysis of the results of the in vitro flow phantom experiment.
Experimental conditions and flow estimations during in vitro experiments on the vessel phantom.
X-ray acquisition parameters and associated dose measurements for a patient case.
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