Utility of perfusion-weighted MR imaging in astrocytomas

Objective: To evaluate the diagnostic value of perfusion weighted magnetic resonance imaging (PWI) in astrocytomas. Methods: PWI were performed in 26 patients with histologically verified astrocytomas. Regional cerebral blood volume (rCBV) maps were calculated from dynamic MR image sets. The rCBV of lesions was expressed as a percentage of the relative rCBV of contralateral normal white matter. The maximum rrCBV of each lesion was correlated with the histopathologic grading of astrocytomas. Results: Nine grade II astrocytomas demonstrated homogeneously rCBV, equal to or higher than that of the corresponding normal white matter. While 7 grade III and 10 grade IV astrocytomas often showed areas of both high and low rCBV. In 2 grade III and 2 grade IV astrocytomas, the lesion demonstrated no obvious contrast enhancement on T1-weighted images but showed large perfusion abnormalities. Mean values of maximum rrCBV in grade II-IV astrocytomas were 0.91±0.18, 3.51±1.01, and 4.75±1.23, respectively. The maximum rrCBV of grade II astrocytomas was significantly lower than grade III (t=6.79, P<0.01) and grade IV (t=9.75, P<0.01), grade III was lower than those of grade IV (t=2.19, P<0.05), the differences were statistically significant. Conclusion: PWI can show the hemodynamic changes of astrocytomas. It's useful in the assessment of histopathologic grade of astrocytomas