Figure 2. (a) Dynamic time course series through the brain using a T₂* weighted acquisition during passage of bolus of contrast agent. Note the decrease in signal intensity within the brain during the passage of the contrast bolus. (b) Signal intensity changes in a large blood vessel (A), grey matter (B) and white matter (C). (c) Calculated changes in contrast concentration derived from the vascular and grey matter curves. Open circles and crosses represent the original data measurements. The solid lines show the result of a gamma variate curve fit to each of the data sets. Note that the curve fitting procedure eliminates the effects of contrast re-circulation in the later phases of the images. (Courtesy of Dr F Calamante.)