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Diffusion-weighted and diffusion tensor imaging of the brain, made easy.

Huisman TA - Cancer Imaging (2010)

Bottom Line: In addition, DWI/DTI allows exploring the microarchitecture of the brain.A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts.This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases.

View Article: PubMed Central - PubMed

Affiliation: Division Pediatric Radiology, Johns Hopkins Hospital, Baltimore, MD 21287-0842, USA. thuisma1@jhmi.edu

ABSTRACT
Diffusion-weighted and diffusion tensor imaging (DWI/DTI) has revolutionized clinical neuroimaging. Pathology may be detected earlier and with greater specificity than with conventional magnetic resonance imaging sequences. In addition, DWI/DTI allows exploring the microarchitecture of the brain. A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts. This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases.

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Graphical display of the range of isotropic towards anisotropic diffusion as can be observed in the various regions of the brain. An FA value of zero represents complete isotropic diffusion (perfect sphere); an FA value of one represents the hypothetical case of complete anisotropic diffusion (narrow ellipsoid).
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Figure 5: Graphical display of the range of isotropic towards anisotropic diffusion as can be observed in the various regions of the brain. An FA value of zero represents complete isotropic diffusion (perfect sphere); an FA value of one represents the hypothetical case of complete anisotropic diffusion (narrow ellipsoid).

Mentions: Based on these data, as well as the DWI and ADC maps, a third map can be calculated: the FA map (Fig. 2). FA is defined as the ratio of the anisotropic component of the diffusion tensor to the whole diffusion tensor and serves as a rotationally invariant scalar that quantifies the shape of the diffusion tensor. FA varies between zero and one. Zero represents maximal isotropic diffusion as in a perfect sphere; one represents maximal anisotropic diffusion as in the hypothetical case of a long cylinder of minimal diameter (Fig. 5). The FA values can also be calculated on a voxel by voxel basis and mapped accordingly. Areas with a high degree of anisotropic diffusion (high FA value) are bright (e.g. corpus callosum, internal capsule), and areas with low anisotropic diffusion are dark (e.g. CSF or gray matter).Figure 5


Diffusion-weighted and diffusion tensor imaging of the brain, made easy.

Huisman TA - Cancer Imaging (2010)

Graphical display of the range of isotropic towards anisotropic diffusion as can be observed in the various regions of the brain. An FA value of zero represents complete isotropic diffusion (perfect sphere); an FA value of one represents the hypothetical case of complete anisotropic diffusion (narrow ellipsoid).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2967146&req=5

Figure 5: Graphical display of the range of isotropic towards anisotropic diffusion as can be observed in the various regions of the brain. An FA value of zero represents complete isotropic diffusion (perfect sphere); an FA value of one represents the hypothetical case of complete anisotropic diffusion (narrow ellipsoid).
Mentions: Based on these data, as well as the DWI and ADC maps, a third map can be calculated: the FA map (Fig. 2). FA is defined as the ratio of the anisotropic component of the diffusion tensor to the whole diffusion tensor and serves as a rotationally invariant scalar that quantifies the shape of the diffusion tensor. FA varies between zero and one. Zero represents maximal isotropic diffusion as in a perfect sphere; one represents maximal anisotropic diffusion as in the hypothetical case of a long cylinder of minimal diameter (Fig. 5). The FA values can also be calculated on a voxel by voxel basis and mapped accordingly. Areas with a high degree of anisotropic diffusion (high FA value) are bright (e.g. corpus callosum, internal capsule), and areas with low anisotropic diffusion are dark (e.g. CSF or gray matter).Figure 5

Bottom Line: In addition, DWI/DTI allows exploring the microarchitecture of the brain.A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts.This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases.

View Article: PubMed Central - PubMed

Affiliation: Division Pediatric Radiology, Johns Hopkins Hospital, Baltimore, MD 21287-0842, USA. thuisma1@jhmi.edu

ABSTRACT
Diffusion-weighted and diffusion tensor imaging (DWI/DTI) has revolutionized clinical neuroimaging. Pathology may be detected earlier and with greater specificity than with conventional magnetic resonance imaging sequences. In addition, DWI/DTI allows exploring the microarchitecture of the brain. A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts. This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases.

Show MeSH