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. Author manuscript; available in PMC: 2013 Nov 28.
Published in final edited form as: AJR Am J Roentgenol. 2013 Sep;201(3):10.2214/AJR.12.9544. doi: 10.2214/AJR.12.9544

TABLE 3.

Perfusion MRI Features Differentiating Recurrent Tumor and Delayed Radiation Necrosis (DRN)

Feature Recurrent Tumor DRN
Contrast enhancement Yes Yes
Time frame Many months to years after radiation therapy Many months to years after radiation therapy
Perfusion (rCBV) Significantly greater than in DRN Significantly less than in recurrent tumor
Permeability (PSR, Ktrans) Significantly greater than in DRN Significantly less than in recurrent tumor

Note—In general, permeability and perfusion threshold values cannot be given because of differences in data acquisition and postprocessing and interpretation. Institutional techniques should be compared with particular studies described. rCBV = relative cerebral blood volume, PSR = percentage signal recovery, Ktrans = transfer constant.