Relationship between the hemodynamic changes on multi-Td pulsed arterial spin labeling images and the degrees of cerebral artery stenosis

To explore the relationship between the hemodynamic changes on multi-Td (delay time) pulsed arterial spin labeling (PASL) images and the degrees of cerebral artery stenosis, and to evaluate the value of multi-Td PASL in detecting the signal changes in cerebral arteries with stenosis.

29 patients with less than 50% stenosis (mild stenosis group) and 22 patients with 50%-69% stenosis (moderate stenosis group) in M1 segment of unilateral middle cerebral artery (MCA) were included in this study. The degrees of MCA stenosis were measured using time of flight MR angiography (TOF MRA). Multi-Td PASL imaging was performed to detect the signal changes in bilateral MCA. We selected and hand-drew bilateral symmetric branches of MCA as regions of interest (ROIs) on eight-Td PASL images. The intensities of ROIs were measured, and the time-signal intensity curves were acquired by post-processing on a MR workstation. SPSS19.0 statistical software was used for statistics. The differences in the peak intensities and the times to peak intensities between the normal and narrowed sides of the mild and moderate stenosis groups were respectively examined by paired-samples t test. The differences in the changes of peak intensities and times to peak intensity of the two sides between the mild and moderate stenosis groups were examined by independent samples t test. A p value less than 0.05 was considered statistically significant.

There were significant difference in the peak intensities (t=-2.720, p=0.011<0.05) and no significant difference in the times to peak intensities (t=-1.279, p=0.212>0.05) between the normal and narrowed sides of the mild stenosis group. There were both significant differences in the peak intensities (t=-6.076, p=0.000<0.05) and times to peak intensities (t=7.232, p=0.000<0.05) between the normal side and narrowed side of the moderate stenosis group. There were both significant differences in the changes of peak intensities (t=-2.11, p=0.040<0.05) and times to peak intensity (t=-4.23, p=0.000<0.05) between the mild and moderate stenosis groups.

The hemodynamic changes on multi-Td PASL images were different with the degrees of cerebral artery stenosis. Moderate stenosis means greater hemodynamic changes in the arteries than mild stenosis. Multi-Td PASL imaging is a promising means to evaluate the hemodynamic changes in cerebral arteries with stenosis.