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 T 1-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.