FIG 4. Images from the case of a 57-year-old woman with a diplopia while looking leftward.

A, Lateral angiographic view shows a left giant internal carotid artery aneurysm (arrow) at the C5 segment between the carotid siphon and the intrapetrous carotid artery. Diplopia related to compression of the left VIth cranial nerve by this aneurysm.

B, Analysis of the time-concentration curves in the ACA (circles) and in both MCA (crosses and squares) shows a cerebral flow alteration at the beginning of the left MCA (squares), downward of the aneurysm, featuring a delayed time-to-peak within this artery.

C, Stable xenon CT values of CBF.

D, Choice of the ACA as the reference artery results in a CBF map (cc/[100 g x min]) with underestimated CBF on the left side, compared with the stable xenon CT values of CBF.

E, Deconvolution of parenchymal time-concentration curves of each cerebral hemisphere by related profiles in ipsilateral MCA avoids such a pitfall