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FIG 3. Sample time-intensity curves and data analysis in a healthy control subject. Vertical gray lines are the raw data. Black and gray curves are polynomic fit, where gray indicates 80% of total signal-intensity increase, CCT = v0 – a0 = 7.3 seconds, where v0 and a0 = turning point of the venous and arterial polynomic fit. Venous rise time 
t = v2 – v1 = 8.2 seconds. Arterial rise time t = a2 – a1 = 4.2 seconds. a1 and v1 = point at 10% total intensity increase, and a2 and v2 = point at 90% total intensity increase.
