Differentiation between recurrent gliomas and radiation necrosis using arterial spin labeling perfusion imaging

Arterial spin labeling (ASL) magnetic resonance (MR) perfusion imaging has been proposed as an effective method to measure brain tumor perfusion. The aim of the present study was to evaluate the utility of this technique in the differentiation of recurrent gliomas from radiation necrosis. Twenty-one patients with surgically treated primary gliomas, including 16 cases of recurrent glioma and 5 of radiation necrosis were examined using 3.0T MR imaging (MRI). ASL and dynamic susceptibility contrast-weighted (DSC) perfusion MRI scans were performed. Maps of normalized cerebral blood flow (CBF) in ASL imaging and cerebral blood volume (CBV) in DSC imaging were computed and analyzed in the regions of interest. In cases of glioma recurrence, the normalized ASL-CBF ratio (4.45±2.72) was higher than that in cases of radiation injury (1.22±0.61) (P<0.01). The normalized DSC-relative CBV ratio was also significantly higher in glioma recurrence (3.38±2.08) than it was in radiation injury (1.09±0.55) (P<0.05). A close linear correlation was found between the ASL and DSC MRI techniques (linear regression coefficient, R=0.85; P=0.005) in the differentiation of recurrent glioma from radiation injury. The results indicate that ASL perfusion is an accurate method of distinguishing between glioma recurrence and radiation necrosis.