• Michael C Lee, Soonmee Cha, Susan M Chang, and Sarah J Nelson.
• Department of Radiology, University of California-San Francisco, San Francisco, California 94143-2532, USA. Michael.Lee@mrsc.ucsf.edu
• J Magn Reson Imaging. 2005 Jun 1; 21 (6): 683-93.

PurposeTo identify radiation-induced changes in the cerebral vasculature of healthy tissue in the first four months following radiotherapy through the analysis of dynamic-susceptibility contrast perfusion imaging.Materials And MethodsDynamic gradient-echo imaging was performed on 22 patients during injection of a bolus of Gd-DTPA contrast. The relative cerebral blood volume (rCBV), maximum DeltaR2* of the first passage of the bolus, and a recirculation parameter were derived from gamma-variate fits of the dynamic data. The white matter (WM) rCBV and peak heights were estimated through correlation with segmented T1-weighted images. A percent recovery to baseline was also computed to further describe the recirculation phase.ResultsA significant elevation of the recirculation phase was observed at doses>15 Gy at two months following radiotherapy. This was reflected in an increased recirculation parameter in the fitted curves in the 15-30, 30-45, and >45 Gy dose groups to 2.8%, 3.8%, and 2.4% above the <15 Gy voxels, as well as in a decline in percent recovery to baseline. A trend toward lower rCBV and peak heights was observed at that same time point.ConclusionThe observed results suggest a dose-dependent decline in vessel density and increase in vascular permeability and/or tortuosity in irradiated normal-appearing brain tissue at two months following radiotherapy.Copyright (c) 2005 Wiley-Liss, Inc.

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