Anoxic Injury-Associated Cerebral Hyperperfusion Identified with Arterial Spin-Labeled MR Imaging

Abstract

BACKGROUND AND PURPOSE: Anoxic brain injury is a devastating result of prolonged hypoxia. The goal of this study was to use arterial spin-labeling (ASL) to characterize the perfusion patterns encountered after anoxic injury to the brain.

Medial Occipital Lobe Hyperperfusion Identified by Arterial Spin-Labeling: A Poor Prognostic Sign in Patients with Hypoxic-Ischemic Encephalopathy

“…The mechanism of hyperperfusion following HIE is not clearly understood but is theorized to result from a delayed loss of vascular resistance following an initial period of hypoperfusion. 6 The mean time to MR imaging from the hypoxic or anoxic insult was 3.2 days in our cohort, which exceeds the 24-to 48-hour period of hypoperfusion following HIE. 4 The preferential involvement of the medial occipital lobes in HIE is incompletely understood but may be due to the high baseline metabolic demand of this region, rendering it more susceptible to hypoxic or anoxic injury.…”

“…4 The preferential involvement of the medial occipital lobes in HIE is incompletely understood but may be due to the high baseline metabolic demand of this region, rendering it more susceptible to hypoxic or anoxic injury. 12 ASL hyperperfusion following HIE has been previously described, 6,7 but selective hyperperfusion involving the medial occipital lobes represents a novel finding. Preferential or isolated restricted diffusion involving the occipital lobes has been reported following HIE, though we did not observe such preferential regional cortical involvement in our patient cohort.…”

“…Hyperperfusion after HIE has also been observed with arterial spin-labeling (ASL) MR imaging in both pediatric and adult patients, but in nonspecific patterns that have often corresponded with regions of restricted diffusion. 6,7 ASL is a noninvasive MR imaging technique that produces perfusion maps that are comparable with contrastbased methods such as dynamic susceptibility contrast MR imaging. 8 Because the brain and kidneys are both very sensitive to hypotension and lack of oxygen, HIE is often accompanied by transient acute renal injury, which can be a contraindication to gadolinium-based contrast agent administration in MR imaging.…”

“…8 Because the brain and kidneys are both very sensitive to hypotension and lack of oxygen, HIE is often accompanied by transient acute renal injury, which can be a contraindication to gadolinium-based contrast agent administration in MR imaging. 9,10 In light of this limitation, we sought to further clarify whether the presence of hyperperfusion, as previously reported in patients with HIE 6 and detected with ASL, could be used as a marker of survival prognosis and to examine its relationship to standard prognostic tests.…”

Influence of selecting EPI readout-encoding bandwidths on arterial spin labeling perfusion MRI

“…To find out what other groups used for bandwidth, we searched the PubMed database with the keyword of "arterial spin labeling MRI" and found about 432 papers. Of those only 19 papers listed values for EPI bandwidth [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. A summary of findings from all the reviewed studies is presented in Table 3 together with echo time, the EPI bandwidth, magnetic field strength, and the type of ASL methods.…”