Document Detail


How to perform diffusion-weighted imaging.
MedLine Citation:
PMID:  11398937     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Diffusion-weighted imaging (DWI) has become an invaluable tool in the management of patients with stroke. DWI relies on detecting the random diffusion of water molecules. In normal tissues this movement may be restricted by the presence of cellular structures, which provide a barrier to free movement. This occurs in myelinated white matter, where movement is restricted more across than along fibres. This directional dependence is termed anisotropic restricted diffusion. The diffusion of water molecules can be made the dominant contrast mechanism within an image by applying large magnetic field gradients. The pulsed gradient spin echo (PGSE) sequence provides sensitivity to diffusion with gradient pulses either side of the 180 degrees refocusing pulse. This sequence is generally heavily T2 weighted. In order to detect normal anisotropic properties within the different components of the medullary core, association, commissural and projection fibres, DWI must be performed with sensitisation in at least three directions. PGSE sequences have been used to obtain the diffusion coefficient (D*), a measure of mobility at the molecular level within tissue. In acute infarction D* is increased; in brain death it is decreased. Diffusion contrast needs to be optimised in relation to the highly T2-dependent nature of PGSE sequences. This also requires a more detailed knowledge of how D* changes in disease, but information on nonischaemic neurological conditions is still very limited.
Authors:
G M Bydder; M A Rutherford; J V Hajnal
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery     Volume:  17     ISSN:  0256-7040     ISO Abbreviation:  Childs Nerv Syst     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-06-11     Completed Date:  2002-01-03     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8503227     Medline TA:  Childs Nerv Syst     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  195-201     Citation Subset:  IM    
Affiliation:
The Robert Steiner Magnetic Resonance Unit, MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK.
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MeSH Terms
Descriptor/Qualifier:
Adult
Anisotropy
Brain / pathology
Brain Damage, Chronic / diagnosis*
Brain Neoplasms / diagnosis*
Cerebral Infarction / diagnosis*
Child
Diffusion
Humans
Image Enhancement*
Infant
Infant, Newborn
Magnetic Resonance Imaging / methods*
Reference Values

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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