Figure 2. Calculated parametric images from a normal brain. Images represent (a) cerebral blood volume (CBV); (b) cerebral blood flow (CBF); (c) mean transit time (MTT); (d) time of arrival (T0); (e) time to peak concentration (TTP) and (f) standard fitting error (SFE). Note that maps of CBV show high levels within the blood vessels, much lower levels in grey matter and the lowest measurements of all in white matter. Maps of CBF show a similar distribution of values. MTT is relatively uniform across the entire brain except for a slight prolongation is in the anterior and posterior cerebral watershed areas, particularly on the right (left of the image). Both T0 and TTP maps show contrast delay in the central white matter as with early arrival in peripheral cortex. The map of SFE shows very low values (red) in areas of high signal to noise ratio corresponding to blood vessels. High values are seen in cortex and the highest of all in the white matter reflecting measurement uncertainty due to be creasing temporal signal to noise ratio in these tissues.