Pretherapeutic radioembolization of CNS tumors: Methods, dosimetry and first clinical experience

Our experience with transarterial radioembolization using 90Y resin particles ({null} 45-75 {mu}m) after selective catheterization of malignant tumors has shown good palliative results in patients with inoperable hepatocellular carcinoma. This method may be applicable for many inoperable tumors or symptomatic metastases, but selective tumor embolization must be documented prior to therapy. We have started examining highly vascularized tumors of the CNS that are routinely embolized mechanically with microparticles of different sizes in order to reduce the perioperative risk of hemorrhage. In 13 patients (5 meningiomas, 3 dural angiomas, 2 metastasis, 2 chemodectomas and 1 dural fibrosarcoma) 100 MBq 99mTc labelled macroaggregates of albumin ({null} 25-50 {mu}m) were injected intraarterially after transfemoral cathererization of the tumor-feeding artery. The activity in the area of embolization and in the lungs was then recorded using a gamma camera, and the pulmonary shunt rates calculated. In this ongoing study, we found three different patterns of embolization: (1) embolization with pulmonary shunt (up to 76% of injected activity; 3 patients), (2) embolization without pulmonary shunt but sometimes considerable peritumoral embolization (6 patients) and (3) superselective embolization without significant pulmonary or peritumoral embolization (5 patients). In patients of group (3) who would qualify for therapeutic radioembolization, dosimetricmore » calculations resulted in tumor doses of 200-1000 Gy for 370 MBq 90Y resin particles.« less