Quantification of differences in spatial and temporal expansion of enhancing areas with bolus and SDI inputs. (A) Normalized area measurements (mean ± standard deviation) are plotted as a function of time for the bolus (n = 8) and step-down infusion (n = 6) protocols. The first scan showed few enhancing pixels and is not plotted. Both inputs showed similarly increasing areas for the first 4 scans plotted. The enhancing area for the bolus input, however, began to decrease after the first 5 scans and continued to decrease for the remainder of the study (scans 6–10). Note that the mean last point has dropped down to nearly the same level as the first point shown (i.e., for the 2nd scan). In comparison, the area of enhancement for the step-down protocol increased for the first 4–5 scans before reaching a relatively steady state (scans 6–10). (B) Plot showing the areas under the curve (AUC) for the two input functions which differed significantly for the bolus versus step-down injections on scans 8 and 9. The difference between the two mean values was significant (*p = 0.03). The values are scaled along the left Y-axis. (C) Plot showing the maximum enhancing pixels from the two inputs as corrected fractions of ipsilateral hemisphere. The SDI enhanced pixels covered about 30% whereas those from bolus covered about 12% of the total, the difference being statistically significant (*p = 0.05). These values are scaled along the right Y-axis; error bars represent standard error of the mean.