Abstract W MP114: Arterial Spin Label Perfusion Imaging in Acute Neonatal Stroke Reveals Hyperperfusion in Association With Cerebral Ischemic Injury

Abstract

Introduction: Perfusion magnetic resonance imaging (pMRI) in adults reveals a hypoperfused region, the ischemic penumbra, related to the fixed ischemic injury shown by diffusion weighted imaging (DWI) in acute stroke. Neonatal stroke has pathophysiology and optimum treatment that remain elusive. We hypothesized that altered regional perfusion accompanies the ischemic injury in focal neonatal stroke. Methods: Neonates (0-28 days of life) underwent MR imaging at 3T fieldstrength. pMRI employed a pseudocontinuous arterial spin labeling (PCASL) sequence with multi-slice echo planar readouts at 3x3x5mm3 resolution with TE/TR = 12ms/3.5s, labeling time = 1.6s, a post-labeling delay = 1.5s, 9 axial slices acquired, scan time ~5 min. Forty label/control image pairs were acquired, subtracted and averaged to obtain contrast maps proportional to quantified cerebral blood flow (CBF). DWI, susceptibility weighted imaging and T2-weighted series were obtained with standard protocols. Acute stroke was classified as arterial or venous. Core infarction was considered to lie in hypointense regions on DWI apparent diffusion coefficient maps. Regional perfusion signal was compared to the ischemic core on DWI and to the homologous uninvolved region in the contralesional hemisphere. Results: Data were collected on 20 neonates, (13 males; median/mean gestational age=38/38.5 weeks) with acute stroke (11 arterial ischemic stroke (AIS); 9 venous) scanned at median postnatal age=1.5 days. Evidence of regional hyperperfusion existed in 10/11 (91%) neonates with AIS and 4/9 (44%) with venous stroke. Hyperperfusion was part of a heterogeneous pattern of hypo- and hyperperfusion in 4 infants with AIS and 3 infants with venous infarct. Electroencephalography data obtained at presentation were available for 19 (95%) of the neonates. Fourteen infants (70%) had either electrographic seizure or focal sharp waves in the same hemisphere as the acute infarction. Conclusion: Arterial spin labeling pMRI can be successfully obtained in acute neonatal stroke. Unlike adults, pMRI often reveals hyperperfusion rather than hypoperfusion in neonates. This hyperperfusion may be due to early spontaneous reperfusion or to the neuronal hyperexcitability of stroke-associated seizure.