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Magnetic resonance imaging of ischemic injury produced by varying severities of photothrombosis differs in neonatal and adult brain
Author(s) -
Tuor Ursula I.,
Qiao Min,
Sule Manasi,
Morgunov Melissa,
Foniok Tadeusz
Publication year - 2016
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3626
Subject(s) - magnetic resonance imaging , neuroscience , functional magnetic resonance imaging , medicine , ischemic injury , nuclear magnetic resonance , ischemia , cardiology , psychology , physics , radiology
Stroke is a major cause of disability in adults and children. Recently, we have developed an adult rat model of minor stroke containing a peri‐infarct region with a modest T 2 increase and mild ischemic damage. We hypothesized that a neonatal minor stroke with mild peri‐ischemic changes could also be produced, but with potential ontogenic differences. Using our minor photothrombosis method, we produced a range of severities of ischemic lesions (mini, minor, moderate and severe) within magnetic resonance imaging (MRI) slices of adult and neonatal rats. In both age groups, the lesion region showed a marked increase in T 2 and diffusion‐weighted intensity and decrease in apparent diffusion coefficient (ADC), corresponding to a cortical infarct detected using fluorojade and hematoxylin and eosin staining. Perilesional regions showed modest increases in T 2 and ADC in adults, but not neonates, and this corresponded to scattered cell death, but not necessarily extravasation of plasma protein, i.e. blood–brain barrier disruption. Mini and minor insults in neonates generally showed homogeneous and rather modest changes in T 2 and ADC. MR perfusion maps demonstrated a penumbral area of greater hypoperfusion in adults compared with neonates. Together, the results indicate that, in neonatal cortex, a similar severity of photothrombosis occurs throughout the area of photoactivation, whereas, in adult brain, spontaneous clot lysis and/or partial thrombosis occurs adjacent to permanently occluded vessels. Thus, by comparing differing severities of photothrombotic ischemia in neonates and adults, ontogenic differences were detectable using MRI, with mature brain having a greater penumbral region. Mild ischemic injury and scattered cell death in both neonates and adults could be identified by a modest increase in T 2 and decrease in ADC. A better understanding of the effects of development on ischemic responses and associated MRI changes will provide a basis for the improved diagnosis of mild or minor ischemic insults relevant to pediatric and adult stroke.