Quantitative measurement of microvascular permeability in human brain tumors achieved using dynamic contrast-enhanced MR imaging: Correlation with histologic grade

BACKGROUND AND PURPOSE: Dynamic contrast-enhanced MR imaging may be used to quantify tissue fractional blood volume (fBV) and microvascular permeabili ty, We tested this technique in patients with brain tumors to assess whethe r these measurements correlate with tumor histologic grade. METHODS: Twenty-two patients with newly diagnosed gliomas underwent MR imag ing followed by surgery, Imaging consisted of one pre- and six dynamic post contrast 3D spoiled gradient-recalled acquisition in the steady state data sets after administration of a single dose (0.1 mmol/kg) of contrast materi al. Signal intensity changes in blood and tissue were kinetically analyzed using a bidirectional two-compartment model, yielding estimates of fBV (mL/ cm(3)) and microvascular permeability (mL/100 cm(3) per minute). Stained tu mor specimens were scored on a four-point scale (1 = low grade, 4 = high gr ade). RESULTS: Histologic examination revealed one grade 1, eight grade 2, seven grade 3, and six grade 4 tumors. fBV values ranged from 0.5% to 13.7%, Perm eability values ranged from -0.4 to 18.8, with a strong correlation (r = 0. 83) to tumor grade. Despite some overlap between the permeability values of specific tumors from different grades, differences in the mean were statis tically significant. There was a weak correlation (r = 0.39) between estima ted fBV and tumor grade, and no statistically significant difference among fBV values in any of the groups. CONCLUSION: This relatively simple method of analysis provides quantitative estimates of fBV and microvascular permeability in human brain tumors, wit h the permeability being predictive of pathologic grade. The technique can be easily implemented on clinical scanners and may prove useful in the asse ssment of tumor biology and in therapeutic trials.