Abstract W P264: Imaging Cerebrovascular Reserve using Blood Flow and Oxygenation Level Dependent: A Study using Acetazolamide Challenge
Introduction: Cerebrovascular reserve (CVR) capacity in patients with chronic stenosis or occlusion of major arteries including the carotid provides valuable information in predicting their risks of developing strokes subsequently1. In the current study, we compared CVR assessment using two MRI methods ASL (arterial spin labeling) and BOLD (blood oxygenation level dependent) with the injection of acetazolamide (Diamox).
Method: A multi-delay ASL (10 post-label delays, first TI=300ms, increment=300ms) sequence was acquired before the injection of Diamox, the BOLD sequence was started for continuous acquisition, 1-5 minutes of baseline images were acquired before the 3-minute infusion, the BOLD sequence ends 15 minutes from the start of Diamox injection. A post-Diamox ASL was then acquired. The CVR was then measured using two metrics for both ASL (CVRasl) and BOLD (CVRbold) to compare the agreement between the two methods.
Results & Discussions: CVR metrics using both ASL and BOLD were reliably obtained in nine patients. Results showed complementary values of both ASL and BOLD CVR measurement. Figure 1(a-f) shows the ASL and BOLD maps as well the CVR metrics in one of the patients. CVRasl map suggests that there is an augmentation deficit in the left posterior region of the brain (arrows in Figure 1g), while strong augmentation was observed in BOLD signal, consistent with high CBF values observed in the DSC CBF map (Fig. 1d). In agreement with hypothesis, BOLD provides complementary information in such regions. Interestingly, in both cases we observed a transient reduction of BOLD signal following the injection of Diamox (see Figure 1f), possibly due to transient increase of the CBV due to the effects of Diamox, similar to the classic observation of “initial dip” of BOLD signal due to task. In conclusion, combining CBF measurement using ASL and BOLD is a promising MR method for assessing cerebrovascular reserve capacity.
References: 1. Gupta A. Stroke. 2012; 43:2884-91.
Author Disclosures: D. Qiu: None. F. Nahab: None. S. Dehkharghani: None.
- © 2015 by American Heart Association, Inc.