Cerebral bloodflow in and around spontaneous malignant gliomas.

Abstract

Knowledge of the cerebral bloodflow (CBF) in and around malignant gliomas is of crucial importance in developing strategies for hyperthermia-, radiation-, and chemo-therapy of these difficult to cure lesions. To gather data regarding this important physiological variable, the perfusion distributions of 26 patients who had either a glioblastoma multiforme or an anaplastic astrocytoma were determined using stable xenon computed tomography (XeCT). Perfusion values were determined for each of the following anatomical regions: low density tumour core, the enhancing active ring of the tumour, the low density peripheral region of edema, an ipsilateral region of normal brain adjacent to the tumour, and a region of remote normal tissue on the contralateral side of the brain. A multiple regression analysis of the logs of the CBF values was used to analyse: (1) the differences in blood perfusion between the anatomical regions; and (2) the association of blood perfusion with various patient and tumour characteristics. Statistically significant differences in perfusion values were found between all of the anatomically outlined regions with the exceptions that the active tumour and edematous regions do not differ significantly from the ipsilateral normal brain tissue. The ipsilateral normal brain tissue adjacent to the tumour was found to have a relative perfusion (relative to the contra-lateral normal brain tissue perfusion) of 0.84, the edematous tissue had a relative perfusion of 0.52, the active tumour 0.78, and the core 0.39. Significant blood flow was present in the low density tumour core, contradicting the frequent assumption that there is zero or minimal blood flow in such regions. Multiple regression analysis was used to look for other variables that might be associated with blood flow after adjusting for the differences between anatomical regions. This analysis found a significant negative correlation between tumour blood-flow and tumour volume. It also estimated that blood flow in GMB tumours was approximately 67% of that in lower grade tumours. Variables that were found not to be significantly correlated with blood flow were: patient sex, multiple lobe involvement, hemisphere involved, treatment status (initial vs recurrent disease), Karnofsky performance status, age and, lobe involved.