Correlation of microvascular permeability derived from dynamic contrast-enhanced MR imaging with histologic grade and tumor labeling index: A study in human brain tumors

Rationale and Objectives. Dynamic contrast material-enhanced magnetic reson ance (MR) imaging may be used to quantify fractional blood volume (fBV) and microvascular permeability in human brain tumors. Hypothesis is that these measurements correlate with tumor histologic made and immunohistologically assessed mitotic activity. Materials and Methods. Thirty-eight patients with newly diagnosed gliomas u nderwent MR imaging consisting of dynamic three-dimensional spoiled gradien t-recalled acquisition in the steady state image sets following bolus injec tions of a single dose of gadodiamide. Signal intensity changes in blood an d tissue were kinetically analyzed, yielding estimates of fBV and microvasc ular permeability (k). Tumor specimens were graded with the World Health Or ganization-II four-point grading score. MIB-1 immunohistochemical labeling (anti-Ki-67 monoclonal antibody) was performed in 22 patients to evaluate m itotic activity. Results. Histologic study revealed nine grade 2, 14 grade 3, and 15 grade 4 tumors. fBV ranged from 0.4% to 24%, k from -0.4 to 31.4 mL/100 cm(3) (.) min, and MIB-1 labeling indexes from 1.7% to 42.8%. Correlation to the tumo r grade was highest for permeability (r = 0.73), followed by the MIB-1 inde x (r = 0.63), and fBV (v = 0.48). Correlation between k and MIB-1 index was strong (r = 0.84). There was no statistically significant difference betwe en the fBV of any of the groups. Despite some overlap between the permeabil ity values of specific tumors from different grades, differences were stati stically significant. The MIB-1 index was significantly different between g rades 3 and 4 but not between grades 3 and 3. Conclusion. Dynamic contrast-enhanced MR imaging allows noninvasive determi nation of tumor fBV and microvascular permeability ii. k is more reliable t han the MIB-1 labeling index for differentiating grade 2 from grade 3 tumor s.