Document Detail

Detection of the ischemic penumbra using pH-weighted MRI.
MedLine Citation:
PMID:  17133226     Owner:  NLM     Status:  MEDLINE    
The classic definition of the ischemic penumbra is a hypoperfused region in which metabolism is impaired, but still sufficient to maintain cellular polarization. Perfusion- and diffusion-weighted MRI (PWI, DWI) can identify regions of reduced perfusion and cellular depolarization, respectively, but it often remains unclear whether a PWI-DWI mismatch corresponds to benign oligemia or a true penumbra. We hypothesized that pH-weighted MRI (pHWI) can subdivide the PWI-DWI mismatch into these regions. Twenty-one rats underwent permanent middle cerebral artery occlusion and ischemic evolution over the first 3.5 h post-occlusion was studied using multiparametric MRI. End point was the stroke area defined by T(2)-hyperintensity at 24 h. In the acute phase, areas of reduced pH were always larger than or equal to DWI deficits and smaller than or equal to PWI deficits. Group analysis showed that pHWI deficits during this phase coincided with the resulting infarct area at endpoint. Final infarcts were smaller than PWI deficits (range 65% to 90%, depending on the severity of the occlusion) and much larger than acute DWI deficits. These data suggest that the outer boundary of the hypoperfused area showing a decrease in pH without DWI abnormality may correspond to the outer boundary of the ischemic penumbra, while the hypoperfused region at normal pH may correspond to benign oligemia. These first results show that pHWI can provide information complementary to PWI and DWI in the delineation of ischemic tissue.
Phillip Zhe Sun; Jinyuan Zhou; Weiyun Sun; Judy Huang; Peter C M van Zijl
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2006-11-29
Journal Detail:
Title:  Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism     Volume:  27     ISSN:  0271-678X     ISO Abbreviation:  J. Cereb. Blood Flow Metab.     Publication Date:  2007 Jun 
Date Detail:
Created Date:  2007-05-22     Completed Date:  2007-07-25     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8112566     Medline TA:  J Cereb Blood Flow Metab     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1129-36     Citation Subset:  IM    
Division of MRI Research, Neurosection, Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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MeSH Terms
Brain Ischemia / diagnosis,  pathology*
Hydrogen-Ion Concentration*
Infarction, Middle Cerebral Artery / pathology
Magnetic Resonance Imaging / methods*
Stroke / diagnosis,  pathology
Grant Support

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