PurposeThis work aims to explore the effect of Blood Brain Barrier (BBB) opening using ultrasound combined with microbubbles injection on cerebral blood flow in rats. MethodsTwo groups of n = 5... Show morePurposeThis work aims to explore the effect of Blood Brain Barrier (BBB) opening using ultrasound combined with microbubbles injection on cerebral blood flow in rats. MethodsTwo groups of n = 5 rats were included in this study. The first group was used to investigate the impact of BBB opening on the Arterial Spin Labeling (ASL) signal, in particular on the arterial transit time (ATT). The second group was used to analyze the spatiotemporal evolution of the change in cerebral blood flow (CBF) over time following BBB opening and validate these results using DSC-MRI. ResultsUsing pCASL, a decrease in CBF of up to 29.6 +/- 15.1%$$ 29.6\pm 15.1\% $$ was observed in the target hemisphere, associated with an increase in arterial transit time. The latter was estimated to be 533 +/- 121ms$$ 533\pm 12\mathrm{1ms} $$ in the BBB opening impacted regions against 409 +/- 93ms$$ 409\pm 93\mathrm{ms} $$ in the contralateral hemisphere. The spatio-temporal analysis of CBF maps indicated a nonlocal hypoperfusion. DSC-MRI measurements were consistent with the obtained results. ConclusionThis study provided strong evidence that BBB opening using microbubble intravenous injection induces a transient hypoperfusion. A spatiotemporal analysis of the hypoperfusion changes allows to establish some points of similarity with the cortical spreading depression phenomenon. Show less
Functional magnetic resonance imaging (fMRI) techniques using the blood-oxygen level-dependent (BOLD) signal have shown great potential as clinical biomarkers of disease. Thus, using these... Show moreFunctional magnetic resonance imaging (fMRI) techniques using the blood-oxygen level-dependent (BOLD) signal have shown great potential as clinical biomarkers of disease. Thus, using these techniques in preclinical rodent models is an urgent need. Calibrated fMRI is a promising technique that can provide high-resolution mapping of cerebral oxygen metabolism (CMRO2). However, calibrated fMRI is difficult to use in rodent models for several reasons: rodents are anesthetized, stimulation-induced changes are small, and gas challenges induce noisy CMRO2 predictions. We used, in mice, a relaxometry-based calibrated fMRI method which uses cerebral blood flow (CBF) and the BOLD-sensitive magnetic relaxation component, R-2 ', the same parameter derived in the deoxyhemoglobin-dilution model of calibrated fMRI. This method does not use any gas challenges, which we tested on mice in both awake and anesthetized states. As anesthesia induces a whole-brain change, our protocol allowed us to overcome the former limitations of rodent studies using calibrated fMRI. We revealed 1.5-2 times higher CMRO2, dependent upon brain region, in the awake state versus the anesthetized state. Our results agree with alternative measurements of whole-brain CMRO2 in the same mice and previous human anesthesia studies. The use of calibrated fMRI in rodents has much potential for preclinical fMRI. Show less
Paschoal, A.M.; Leoni, R.F.; Pastorello, B.F.; Osch, M.J.P. van 2021
Purpose: To monitor the complete passage of the labeled blood through the vascular tree into tissue and improve the quantification of ASL maps, we evaluated the effect of 3D gradient and spin -echo... Show morePurpose: To monitor the complete passage of the labeled blood through the vascular tree into tissue and improve the quantification of ASL maps, we evaluated the effect of 3D gradient and spin -echo (GRASE) readout segments on temporal SNR (tSNR) and image blurriness for time -encoded pseudo -continuous arterial spin labeling and the effect of flow -compensation gradients on the presence of intravascular signal.Methods: Fifteen volunteers were scanned using time -encoded pCASL with 2D EPI and single -segment, two -segments, and three -segments 3D-GRASE readouts with first -order flow compensation (FC) gradients. Two -segments 3D-GRASE scans were acquired with 25%, 50%, 75%, and 100% of full first -order FC. Temporal SNR was assessed, and cerebral blood flow and arterial blood volume were quantified for all readout strategies.Results: For single -segment 3D GRASE, tSNR was comparable to 2D EPI for perfu sion signal but worse for the arterial signal. Two -segments and three -segments 3D GRASE resulted in higher tSNR than 2D EPI for perfusion and arterial signal. The arterial signal was not well visualized for 3D-GRASE data without. FC. Visualization of the intravascular signal at postlabeling delays of 660 ms and 1060 ms was restored with EC. Adequate visualization of the intravascular signal was achieved from 75% of FC gradient strength at a postlabeling delay of 660 ms. For a postlabeling delay of 1060 ms, full-FC gradients were the best option to depict intravascularConclusion: Segmented GRASE provided higher effective tSNR compared with 2D-EPI and single -segment GRASE. Flow compensation with GRASE readout should be carefully controlled when applying for time -encoded pCASL to visualize intravascular signal. Show less
Bones, I.K.; Harteveld, A.A.; Franklin, S.L.; Osch, M.J.P. van; Hendrikse, J.; Moonen, C.T.W.; ... ; Stralen, M. van 2019
