Assessment of hypertensive cerebrovascular alterations with multiband Look-Locker arterial spin labeling.

PURPOSE

To quantitatively assess the hypertension-induced cerebrovascular alterations by measuring the dynamics of arterial spin labeling (ASL) signals.

MATERIALS AND METHODS

The multiband Look-Locker ASL (MB LL-ASL) technique was evaluated in comparison to a single-band LL-ASL for three healthy subjects. Also, seven healthy subjects were scanned to determine the strength of the vascular crushing gradients applied to separate arterial from tissue ASL signal. With the optimized MB LL-ASL technique, multiple parameters, cerebral blood flow (CBF), transit times to artery (t ), and capillary (t ), delivery duration of labeled blood (τ), and arterial blood volume (CBV ), were simultaneously quantified for age-matched eight control and eight hypertensive subjects with 259 msec of temporal resolution and 20 slices covering the whole-brain region at 3T.

RESULTS

While CBF of hypertensives were comparable with those of normotensives (CBF of normotensives vs. hypertensives = 62.2 ± 6.87 vs. 61.9 ± 8.94 ml/100g/min, P = 0.960 for the whole gray matter), t and τ were prolonged in hypertensives in most brain regions (t  = 1.30 ± 0.09 vs. 1.76 ± 0.16 sec, P = 0.034; τ = 1.46 ± 0.10 vs. 2.30 ± 0.22 sec, P = 0.006 for the whole gray matter). Two regions showed the increased CBV in hypertensives compared to normotensives (hippocampus and thalamus with P = 0.009 and 0.035, respectively).

CONCLUSION

Hypertension slows the perfusion dynamics, while the remaining CBF is unchanged. A detailed characterization of regional cerebrovascular impairments by MB-LL-ASL technique provides better understanding of hypertension-induced cerebrovascular modifications.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:663-672.