Fig 1.
Description of ROI definition in a representative patient.
MR-angiography shows no flow in the right intracranial ICA and MCA. TTP-images were thresholded according to different degrees of perfusion delay and perfusion delay ranges as compared to the contralateral unaffected hemisphere. The threshold >0 seconds represents the entire perfusion-disturbed area in relation to the upper limit of normoperfusion in the unaffected hemisphere. Areas of perfusion delay were manually outlined in order to generate ROIs which were then transferred to the coregistered T2’- and rCBV-maps. In order to quantify T2’ and rCBV in corresponding areas of the unaffected hemisphere, ROIs were mirrored to the contralateral side. MTT-maps were processed accordingly. ToF: time-of-flight; MRA: MR-angiography; MIP: Maximum Intensity Projection; TTP: time-to-peak; sec: seconds; rCBV: relative cerebral blood volume.
Fig 2.
Boxplots of median hemispheric ratios of T2’ and rCBV for areas with different degrees of perfusion delay ranges and perfusion delays on TTP- (A, B) and MTT- (C, D) maps. Asterisks above the boxplots indicate significant changes of T2’ and rCBV as compared to contralateral unaffected tissue. *: p<0.05; **: p< 0.01; n.s.: not significant; sec: seconds; TTP: time-to-peak; MTT: mean transit time; rCBV: relative cerebral blood volume.
Table 1.
Values and hemispheric ratios of T2’ and rCBV for different degrees of perfusion delay in perfusion-disturbed and corresponding normoperfused tissue.
Table 2.
Values and hemispheric ratios of R2’ und rCBV for different degrees of perfusion delay in perfusion-disturbed and corresponding normoperfused tissue.
Fig 3.
Scatter plot of hemispheric ratios of T2’ and rCBV for all areas with TTP- (59 values calculated from 177 ROIs) (A) and MTT- (101 values calculated from 303 ROIs) (B) delay. Broken lines indicate unity for T2’ and rCBV (hemispheric ratio = 1). Lower right quadrant (black dots) contains ROIs with reduced T2’ (hemispheric ratio<1) and simultaneously elevated rCBV (hemispheric ratio>1). rCBV: relative cerebral blood volume.
Fig 4.
Scatter plot of hemispheric ratios of R2’ and rCBV for all areas with TTP- (A) and MTT-delay (B). Broken lines indicate unity of R2’ and rCBV in both hemispheres (hemispheric ratio = 1). Upper right quadrant (black dots) contains ROIs with increased R2’ (hemispheric ratio>1) and simultaneously elevated rCBV (hemispheric ratio>1). rCBV: relative cerebral blood volume.