Simultaneous measurement of cerebral blood flow and transit time with turbo dynamic arterial spin labeling (Turbo‐DASL): Application to functional studies

Abstract

A turbo dynamic arterial spin labeling (Turbo-DASL) method was developed to simultaneously measure cerebral blood flow (CBF) and blood transit time with high temporal resolution. With Turbo-DASL, images were repeatedly acquired with a spiral readout after small-angle excitations during pseudo-continuous ASL and control periods. Turbo-DASL experiments at 9.4 T, without and with diffusion gradients were performed on rats anesthetized with isoflurane or α-chloralose. We determined blood transit times from carotid arteries to cortical arterial vessels (TTa) from data obtained without diffusion gradients, and to capillaries (TTc) from data obtained with diffusion gradients. Cerebral arterial blood volume (CBVa) was also calculated. At the baseline condition, both CBF and CBVa in the somatosensory cortical area were 40–50% less in rats with α-chloralose than in rats with isoflurane, while TTa and TTc were similar for both anesthetics. Absolute CBF and CBVa were positively correlated, while CBF and TTc were slightly negatively correlated. During forepaw stimulation, CBF increase was 15±3% (n=7) vs. 60±7% (n=5), and CBVa increase was 19±9% vs. 46±17% under isoflurane vs. α-chloralose anesthesia, respectively; and CBF vs. CBVa changes were highly correlated. However, TTa and TTc were not significantly changed during stimulation. Our results support that arterial CBV increase plays a major role in functional CBF changes.

Comparison of retinal and cerebral blood flow between continuous arterial spin labeling MRI and fluorescent microsphere techniques

“…Our CASL MRI CBF values are similar to previous reports . Cortical CBF has been reported to be 0.74 mL/g/min by H 2 17 O MRI , 0.91 mL/g/min by flow‐sensitive alternating inversion recovery (FAIR) MRI and 0.85 mL/g/min by iodoantipyrine autoradiography .…”

“…In the MRI and PET literatures, subcortical CBF is overall smaller or similar to cortical CBF , as we observed in our study. Our microsphere data showed that striatal CBF by 8 μm microspheres was higher than that by MRI.…”

Blood oxygenation level dependent, blood volume, and blood flow responses to carbogen and hypoxic hypoxia in 9L rat gliomas as measured by MRI

“…A further factor to be considered is that all experiments here were performed under isoflurane anesthesia. Isoflurane may increase baseline CBF , but have little or no effect on hypercapnic CBF response in normal rat brain. It is not known, however, whether isoflurane influences cerebral and tumor vasculatures differently.…”

Oxygen metabolism MRI – A comparison with perfusion imaging in a rat model of MCA branch occlusion and reperfusion

“…Continuous ASL employs magnetic labelling, tagging, of arterial blood through the application of an up to seconds long inversion RF pulse to the cervical arteries (50,51). The magnetic inversion of the protons contained in the blood reaching the brain causes a marginal T1-signal loss that is harnessed in a so-called tag-image, and which is subsequently compared to a non-tagged control.…”