Hippocampal-Sparing and Target Volume Coverage in Treating 3-10 Brain Metastases: A Comparison of 192-Source Cobalt Radiosurgery, Single-Isocenter VMAT, and Nonisocentric Robotic Arm-Mounted Linac Stereotactic Radiosurgery

Abstract

MD Anderson, Houston, TXPurpose/Objective(s): Thalamic tumors represent 5.2% of all intracranial tumors and are typically diagnosed in the pediatric population. These tumors arise from glial cells with an aggressive behavior and high grade histology. They have a poor prognosis. The aim of this study was to find new approaches for defining the clinical target volume for these tumors. Materials/Methods: Clinical data was collected form archived files of 30 patients diagnosed with thalamic gliomas based on pathologic and radiologic criteria. Results: Three patterns of tumor spread were found. The first pattern followed the thalamic tributaries of the posterior part of the internal cerebral veins. These were the anterior and superior thalamic veins. For the second pattern the close proximity of the internal cerebral vein branches of the superior thalamic veins was a potential route of spread between the medial surfaces of the thalami. In addition to spread across the midline tumors could also spread along the adjacent tectal, pineal and/or vermian veins. The third pattern of thalamic tumor spread was found in gliomas which use the anterior tributaries of the internal cerebral venous architecture of the posterior and inferior branches from the basal vein of Rosenthal. Conclusion: Thalamic gliomas spread upon the peritumoral architecture of the perivenous/subglial Scherer structures and this knowledge should be used for redefining the clinical target volume for radiation therapy in thalamic gliomas.