Diffusion tensor imaging for differentiation of recurrent brain tumor and radiation necrosis after radiotherapy--three case reports.

Fractional anisotropy (FA) is influenced by histological data such as cellularity, vascularity and/or fiber structure in astrocytic tumors. We describe two patients with tumor recurrence and one patient with radiation necrosis who were diagnosed using assessment of FA value. The assessment of FA value in enhanced lesions after radiotherapy may be able to differentiate radiation necrosis from tumor recurrence.