Volume 21, Issue 6 p. 581-588
Research Article

Can we differentiate true white matter fibers from pseudofibers inside a brain abscess cavity using geometrical diffusion tensor imaging metrics?

Manoj Kumar

Manoj Kumar

Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India

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Rakesh K. Gupta

Corresponding Author

Rakesh K. Gupta

Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India

Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareily Road, Lucknow, UP, India, 226014.Search for more papers by this author
Kavindra Nath

Kavindra Nath

Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India

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R. K. S. Rathore

R. K. S. Rathore

Department of Mathematics and Statistics, Indian Institute of Technology, Kanpur, UP, India

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Getaneh Bayu

Getaneh Bayu

Department of Mathematics and Statistics, Indian Institute of Technology, Kanpur, UP, India

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Richa Trivedi

Richa Trivedi

Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India

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Mazhar Husain

Mazhar Husain

Department of Neurosurgery, King George's Medical University, Lucknow, UP, India

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Kashi N. Prasad

Kashi N. Prasad

Department of Microbiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India

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R. P. Tripathi

R. P. Tripathi

Department of Radiodiagnosis, Institute of Nuclear Medicine and Allied Sciences, New Delhi, India

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Ponnada A. Narayana

Ponnada A. Narayana

Department of Diagnostic and Interventional Imaging, University of Texas Medical School at Houston, Houston, TX, USA

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First published: 30 November 2007
Citations: 28

Abstract

High fractional anisotropy (FA) usually reflects the orientation and integrity of white matter (WM) fibers. Other regions of increased FA have been described, such as brain abscesses, developing cortex, and areas of hemorrhage. It may not be possible to differentiate true fibers from the pseudofibers found inside an abscess cavity on the basis of FA and mean diffusivity (MD). The aim of this study was to differentiate true WM fibers from pseudo WM tracts inside the abscess cavity using geometrical diffusion tensor imaging metrics [linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS)]. Diffusion tensor imaging was performed in 42 patients with brain abscess and 10 age/sex-matched controls. Automated segmentation using Java-based software divided the abscess cavity into two sub-regions with FA < 0.20 and FA ≥ 0.20. Quantitation was carried out on the sub-regions of the abscess cavity with FA ≥ 0.20. In healthy controls, regions of interest were placed on the corpus callosum, posterior limb of the internal capsule, and periventricular and subcortical WM. Significantly increased CP values were observed inside the abscess cavity compared with various normal WM regions. Significantly increased FA and CL values were observed in the abscess cavity compared with subcortical WM only. However decreased FA and CL values were observed in the cavity compared with the corpus callosum, posterior limb of the internal capsule, and periventricular WM. The 95% confidence intervals of means for the abscess cavity were well separated from those for WM in the case of CL and CP; however, they overlapped in the case of FA, MD, and CS. High CP with low CL inside the abscess cavity suggests that the shape of the diffusion tensor is predominantly planar, whereas it is linear in WM tracts. These geometrical indices may have advantages over FA for differentiating true from pseudo WM tracts inside the abscess cavity. Copyright © 2007 John Wiley & Sons, Ltd.