Intratumoral arteriovenous shunting in malignant gliomas.

OBJECTIVE: Intratumoral arteriovenous shunting in glioblastomas has been suspected but neither proven nor quantified. METHODS: Using a previously described technique of selective intra-arterial intratumoral injection of Tc-99m-labeled microparticles (macroaggregated albumin), we measured the amount of radioactivity, by cerebral and pulmonary scintigraphy, in seven patients with malignant gliomas (six with glioblastomas and one with an anaplastic oligodendroglioma). The pulmonary shunt index was calculated as a percentage from the pulmonary/pulmonary plus cerebral radioactivity ratio. RESULTS: The results revealed a mean pulmonary shunt index of 67% (range, 47-89%), indicating that most of the microparticles injected into the tumor via the arterial route bypassed the tumor and reached the lungs. The measured arteriovenous shunting was greater when the injection was performed in an artery exclusively perfusing the tumor. CONCLUSION: Important intratumoral arteriovenous shunting exists in glioblastomas. The potential consequences of this finding for intra-arterial treatment strategies are discussed.