FIG 6.

Variation in ROI placement can alter time-density curves and calculated peak times due to the in-plane vessel course and contrast mixing. Left internal carotid arteriogram in a lateral projection demonstrates a left parietal lobe AVM supplied by the left anterior cerebral artery with venous drainage into a dilated left internal cerebral vein. A, Four arterial ROIs were placed along the course of the left anterior cerebral artery feeder with varying proximity to the nidus. B, Four venous ROIs were placed along the course of the draining vein that empties into the left internal cerebral vein with varying proximity to the nidus. C, The resulting time-density curves are not reproducible. D, The resulting peak times are not reproducible.