FIG 4. Mean stdTTTP values with 95% confidence intervals (minimum to maximum).

A, Values measured in border zones. The stdTTP was not significantly prolonged in the anterior (a-BZ) and posterior (p-BZ) border zones in hemispheres supplied by a normal ICA in group 1 (grp 1; a-BZ and p-BZ [normal ICA]) compared with the control (grp 0; a-BZ and p-BZ [normal ICA]). All other groups showed significantly prolonged stdTTP values. In relation to a proposed limit of 3.5 s for the stdTTP value in border zones, this was moderate in hemispheres supplied by a highly stenosed ICA (grp 1; a-BZ and p-BZ [stenotic ICA] and grp 2; a-BZ and p-BZ [stenotic ICA]), but severe in hemispheres isolateral to an occluded ICA (grp 2; a-BZ and p-BZ [occluded ICA]).

B, Values measured in the CVT of the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries showed behavior completely different from that of border zones. Only in the CVT of the MCA in group 2 (grp 2; MCA [occluded ICA]), in whom the isolateral ICA was occluded and the contralateral ICA showed a high-grade stenosis, was the stdTTP significantly increased compared with the control group (grp 0).