Glial neoplasms: Dynamic contrast-enhanced T2*-weighted MR imaging

PURPOSE: To evaluate the role of T2*-weighted echo-planar perfusion imaging by ;- using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood v olume(CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy. MATERIALS AND METHODS: MR imaging was performed in 29 patients by using a f irst-pass gadopentetate dimeglumine; T2*-weighted; echo-planar perfusion se quence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV;This information formed;the basis for targeting the stereotactic biopsy. Relative CBV values were compu ted with a nondiffusible tracer model. the relative CBV of-lesions was expr essed;ed a; a percentage of the relative CBV of normal white matter. The ma ximum relative CBV of each lesion was correlated with the histopathologic g rading of astrocytomas obtained from samples from stereotactic biopsy or vo lumetric resection. RESULTS: The maximum relative CV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7,with a;mean of 5,07 +/- 2.79 (+/- SD), and in the low-gr ade cohort (n = 3) varied from 0.92 to 2.19, with a mean:of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P <.001; Stu dent t test) CONCLUSION:Echo-planar, perfusion imaging is useful inthepreoperative asses sment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invalu able in the precise targeting of the stereotactic biopsy.