Assessment of diagnostic accuracy of perfusion MR imaging in primary and metastatic solitary malignant brain tumors.

PURPOSE: The purpose of this study was to estimate the diagnostic accuracy of relative cerebral blood volume (rCBV) measurement in preoperative grading and differentiation of solitary intra-axial malignant brain tumors. METHODS: Thirty-six low-grade glial tumors (LGGTs), 22 high-grade glial tumors (HGGTs), and 17 metastases (METs) were prospectively evaluated by MR imaging and standard dynamic susceptibility contrast-enhanced gradient echo, echoplanar imaging during first pass of a bolus injection of contrast material. Normalized rCBV values from tumoral (rCBV(T)) and peritumoral (rCBV(P)) areas were calculated by standard software and statistically tested independently. RESULTS: The mean differences of rCBV(T) and rCBV(P) values between LGGT (2.30 +/- 1.12 and 1.18 +/- 0.24) and HGGT (5.42 +/- 1.52 and 2.17 +/- 0.82) (P < .001); HGGTs and METs (3.21 +/- 0.98 and 0.97 +/- 0.09) (P < .001); and LGGTs and METs (P < .05 and P < .001, respectively) were significant. No clear cutoff value was present. A clear rCBV(T) cutoff value of 2.6 was detected for differentiation of low- (1.75 +/- 0.38; LGA) versus high-grade (4.78 +/- 0.99; HGA) astrocytomas when nonastrocytic glial tumors were excluded. The rCBV(T) values were linearly correlated with degree of malignancy (r = 0.869; P < .001). Cutoff rCBV(P) values of 1.1 and 1.2 were quite effective in differentiation of METs from LGGTs and HGGTs, respectively. The overall efficacy of rCBV was higher in grading than in differentiation. CONCLUSION: The diagnostic accuracy of rCBV measurement is higher in grading of glial brain tumors than in differentiation of HGGTs from solitary intra-axial METs. The astrocytic and nonastrocytic glial tumors have to be evaluated separately for precise grading.