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BioMed Research International
Volume 2015 (2015), Article ID 641023, 9 pages
http://dx.doi.org/10.1155/2015/641023
Research Article

The Diagnostic Ability of Follow-Up Imaging Biomarkers after Treatment of Glioblastoma in the Temozolomide Era: Implications from Proton MR Spectroscopy and Apparent Diffusion Coefficient Mapping

1Department of Diagnostic Imaging, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic
2Department of Diagnostic Imaging, St. Anne’s University Hospital Brno, 656 91 Brno, Czech Republic
3International Clinical Research Center, St. Anne’s University Hospital Brno, 656 91 Brno, Czech Republic
4Department of Radiation Oncology, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic
5Department of Radiation Oncology, Masaryk Memorial Cancer Institute, 656 53 Brno, Czech Republic
6Department of Neurosurgery, St. Anne’s University Hospital Brno, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic
7Department of Neurosurgery, St. Anne’s University Hospital Brno, 656 91 Brno, Czech Republic

Received 23 January 2015; Revised 25 April 2015; Accepted 27 April 2015

Academic Editor: Murat Gokden

Copyright © 2015 Martin Bulik 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

Objective. To prospectively determine institutional cut-off values of apparent diffusion coefficients (ADCs) and concentration of tissue metabolites measured by MR spectroscopy (MRS) for early differentiation between glioblastoma (GBM) relapse and treatment-related changes after standard treatment. Materials and Methods. Twenty-four GBM patients who received gross total resection and standard adjuvant therapy underwent MRI examination focusing on the enhancing region suspected of tumor recurrence. ADC maps, concentrations of N-acetylaspartate, choline, creatine, lipids, and lactate, and metabolite ratios were determined. Final diagnosis as determined by biopsy or follow-up imaging was correlated to the results of advanced MRI findings. Results. Eighteen (75%) and 6 (25%) patients developed tumor recurrence and pseudoprogression, respectively. Mean time to radiographic progression from the end of chemoradiotherapy was 5.8 ± 5.6 months. Significant differences in ADC and MRS data were observed between those with progression and pseudoprogression. Recurrence was characterized by N-acetylaspartate ≤ 1.5 mM, choline/N-acetylaspartate ≥ 1.4 (sensitivity 100%, specificity 91.7%), N-acetylaspartate/creatine ≤ 0.7, and ADC ≤ 1300 × 10−6 mm2/s (sensitivity 100%, specificity 100%). Conclusion. Institutional validation of cut-off values obtained from advanced MRI methods is warranted not only for diagnosis of GBM recurrence, but also as enrollment criteria in salvage clinical trials and for reporting of outcomes of initial treatment.