Arterial Spin Labeling Method as a Supplemental Predictor to Distinguish Between High- and Low-Grade Gliomas.

Abstract

Preoperative evaluation of malignancy in gliomas is important for surgical planning, particularly to determine whether a 1,3-bis-2-chloroethyl-1-nitrosourea wafer should be placed into the tumor cavity. In some cases, the intraoperative pathologic diagnosis of World Health Organization grade differs from the final diagnosis. Supplemental methods in addition to the routine contrast tomography or magnetic resonance imaging sequences may provide a more accurate preoperative diagnosis. Because tumor vascularity has been useful in distinguishing between low- and high-grade gliomas, we evaluated the accuracy of the arterial spin labeling (ASL) method, which could measure the cerebral blood flow (CBF) without using contrast medium, to determine the malignancy of gliomas. This study included 102 patients with glioma (grade II, n= 40; grade III, n= 18; grade IV, n= 44). All patients underwent ASL to determine the tumor blood flow (TBF) and CBF in the middle cerebral region. The relative tumor vascular index (tVI), which is calculated as TBF divided by CBF in the contralateral middle cerebral region, was used to avoid dispersion of the absolute TBF value. tVI was significantly greater (1.46 ± 0.751) in high-grade gliomas than in low-grade gliomas (1.05±0.343) (P= 0.003). As for each grade, tVI was statistically higher in grade IV than in grade II (P= 0.03) gliomas. The noninvasive ASL method provides additional information to distinguish high-grade glioma from low-grade gliomas without using contrast medium.