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BioMed Research International
Volume 2014 (2014), Article ID 647356, 9 pages
http://dx.doi.org/10.1155/2014/647356
Clinical Study

Diffusion Tensor Histogram Analysis of Pediatric Diffuse Intrinsic Pontine Glioma

1Pediatric Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Building 10, Room 1-5750, 9000 Rockville Pike, Bethesda, MD 20892, USA
2In Vivo NMR Center, National Institute of Neurological Disorders and Stroke, National Institutes of the Health, Bethesda, MD 20892, USA
3Program on Pediatric Imaging and Tissue Sciences, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
4Biostatistics and Data Management Section, National Cancer Institute, Center for Cancer Research, National Institutes of the Health, Bethesda, MD 20892, USA
5Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912, USA

Received 12 February 2014; Accepted 24 May 2014; Published 11 June 2014

Academic Editor: Roberta Rudà

Copyright © 2014 Emilie A. Steffen-Smith et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose. To evaluate tumor structure in children with diffuse intrinsic pontine glioma (DIPG) using histogram analyses of mean diffusivity (MD), determine potential treatment and corticosteroid-related effects on MD, and monitor changes in MD distributions over time. Materials and Methods. DTI was performed on a 1.5T GE scanner. Regions of interest included the entire FLAIR-defined tumor. MD data were used to calculate histograms. Patterns in MD distributions were evaluated and fitted using a two-normal mixture model. Treatment-related effects were evaluated using the statistic for linear mixed models and Cox proportional hazards models. Results. 12 patients with DIPG underwent one or more DTI exams. MD histogram distributions varied among patients. Over time, histogram peaks became shorter and broader ( ). Two-normal mixture fitting revealed large lower curve proportions that were not associated with treatment response or outcome. Corticosteroid use affected MD histograms and was strongly associated with larger, sharper peaks ( , ). Conclusions. MD histograms of pediatric DIPG show significant interpatient and intratumoral differences and quantifiable changes in tumor structure over time. Corticosteroids greatly affected MD and must be considered a confounding factor when interpreting MD results in the context of treatment response.