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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 27:402-408, February 2006
© 2006 American Society of Neuroradiology

BRAIN

Effects of Dexamethasone on Cerebral Perfusion and Water Diffusion in Patients with High-Grade Glioma

M.E. Bastin^a, T.K. Carpenter^b, P.A. Armitage^b, S. Sinha^b, J.M. Wardlaw^b and I.R. Whittle^b

^a From the Department of Medical and Radiological Sciences (Medical Physics), University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
^b Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom

Address correspondence to Mark E. Bastin, DPhil, Department of Medical and Radiological Sciences (Medical Physics), University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, United Kingdom

BACKGROUND AND PURPOSE: The mechanisms by which the glucocorticoid dexamethasone produces its therapeutic action in patients with intracranial tumors still remain unclear. The purpose of this study was to investigate whether dexamethasone affects cerebral perfusion and water molecule diffusion by using quantitative dynamic susceptibility contrast perfusion MR imaging (DSC-MR imaging) and diffusion tensor MR imaging (DT-MR imaging).

METHODS: Ten consecutive patients with glioblastoma multiforme underwent DSC-MR imaging and DT-MR imaging before and 48–72 hours after dexamethasone treatment (16 mg/day). Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and water mean diffusivity (<D>) were measured for enhancing tumor, nonenhancing peritumoral edematous brain, and normal-appearing contralateral white matter before and after steroid therapy. The percentage change in CBF, CBV, MTT, and <D> for the 3 tissue types was calculated for each patient, a mean value obtained for the population, and the statistical significance determined by using a paired-samples Student t test.

RESULTS: After dexamethasone treatment, there was no significant change in tumor CBF, CBV, or MTT. Edematous brain CBV and MTT were also unchanged. There was, however, an increase in edematous brain CBF (11.6%; P = .05). <D> was reduced in both enhancing tumor (–5.8%; P = .001) and edematous brain (–6.0%; P < .001). There was no significant change in CBF, CBV, MTT, or <D> for normal-appearing contralateral white matter after treatment.

CONCLUSION: These data suggest that dexamethasone does not significantly affect tumor blood flow but may, by reducing peritumoral water content and local tissue pressure, subtly increase perfusion in the edematous brain.