NCOG-29. INFLUENCE OF RADIATION DOSES TO HIPPOCAMPAL SUBVOLUMES ON MEMORY OUTCOMES IN PITUITARY TUMORS: DOES THE ENTIRE HIPPOCAMPUS NEED TO BE SPARED?

Abstract INTRODUCTION In patients treated with radiation (RT), doses to hippocampus influence neurocognitive outcomes. However, the role of hippocampal subvolumes in memory functioning has not been reported, which prompted current study. METHODS Adults ( > 18 years) pituitary tumors fractionated RT (45 Gy/ 25 fractions/ 5 weeks) were accrued prospective Hippocampus was delineated on T1-weighted 3D-FSPGR sequences 1mm slice thickness. The head, body, and tail drawn for study based consensus two neuroradiologists. anatomical landmarks were: head (basilar artery interpeduncular cistern), body (interpeduncular cistern superior colliculus), (beyond colliculus). Memory assessment done pre-RT months post-RT by dedicated neuropsychologist using Weschler Scale. dose-volume parameters (maximum, mean, D10-D100) extracted from bilateral individually, correlated Binary endpoints 5% drop quotient (MQ) or at used analysis an independent t-test Mann Whitney test as appropriate. RESULTS Of included analysis, 11 had MQ months. left right D10, D20, D30 significantly higher decline. For subvolumes, only dose statistically significant impact MQ. Mean heads 26 Gy 24 compared 21 19 Gy, respectively, other group. CONCLUSION Doses shown short-term memory. appeared pilot study, opening a window exploring stricter constraints towards primary metastatic brain tumors.