Comparison of microvascular permeability measurements, K(trans), determined with conventional steady-state T1-weighted and first-pass T2*-weighted MR imaging methods in gliomas and meningiomas.

BACKGROUND AND PURPOSE

The widely accepted MR method for quantitating brain tumor microvascular permeability, K(trans), is the steady-state T1-weighted gradient-echo method (ssT1). Recently the first-pass T2*-weighted (fpT2*) method has been used to derive both relative cerebral blood volume (rCBV) and K(trans). We hypothesized that K(trans) derived from the ssT1 and the fpT2* methods will correlate differently in gliomas and meningiomas because of the unique differences in morphologic and functional status of each tumor vascular network.

METHODS

Before surgery, 27 patients with newly diagnosed gliomas (WHO grade I-IV; n = 20) or meningiomas (n = 7) underwent conventional anatomic MR imaging and 12 dynamic ssT1 acquisitions followed by 60 dynamic fpT2* images before and after gadopentate dimeglumine administration. The 3 hemodynamic variables-fpT2* rCBV, fpT2* K(trans), and ssT1 K(trans)-were calculated in anatomically identical locations and correlated with glioma grade. The fpT2* K(trans) values were compared with ssT1 K(trans) for gliomas and meningiomas.

RESULTS

All 3 hemodynamic variables displayed distinct distributions among grades 2, 3, and 4 gliomas by using the Kruskal-Wallis test. Only K(trans) values, and not rCBV, could differentiate between grade 4 and lower-grade gliomas by using the Wilcoxon rank sum test. The fpT2* K(trans) was highly predictive of ssT1 K(trans) for gliomas, with an estimated regression coefficient of 0.49 (P < .001). For meningiomas, however, fpT2* K(trans) values correlated poorly with ssT1 K(trans) values (r = 0.26; P = .74).

CONCLUSION

Compared with rCBV, K(trans) values derived from either ssT1 or fpT2* were more predictive of glioma grade. The fpT2* K(trans) was highly correlated with ssT1 K(trans) in gliomas but not in meningiomas.