Permeability Map As an Imaging Biomarker to Distinguish Progression From Pseudoprogression in High-Grade Glioma

Combination temozolomide and radiation significantly prolongs survival compared with radiation alone and has become standard treatment for glioblastoma multiforme (GBM). Response assessment in GBM is difficult as a result of the frequent occurrence of early imaging changes indistinguishable from tumor progression, termed pseudoprogression. The majority of patients remain clinically stable. It is often unclear whether current therapy should be maintained or second-line therapy initiated. The incidence of pseudoprogression after concurrent chemoradiation is15%to 30%. A potential mechanism of pseudoprogression is that radiation-induced vascular changes may lead to focal transient increase in gadolinium enhancement. Dynamic contrast-enhanced (DCE) MR imaging provides a noninvasive means for quantifying tumor vascular properties.