P01.149 Low-grade glioma post-Radiation therapy surveillance with advanced imaging techniques

Abstract

BACKGROUND: Optimal sequential strategy in LGG patients is complex: beyond the role of each individual treatment surgery (S); radiation therapy (RT); chemotherapy (CT), second effects can potentiate the effect of each treatment. With late toxicities concerns as median survival range 5 to 15 years with better prognosis and treatment response for pts with 1p/19q codeletion and IDH1 mutation. Symptoms mainly decreased seizures and magnetic resonance (MRI) evaluation is part of clinical follow-up. Using advanced MRI techniques such as Perfusion can help distinguish pseudoprogression (PP) from true progression (TP), which is a major concern since PP in LLG can occur up to 20%. MATERIAL AND METHODS: Review in Mosaiq® and PACS imaging database, adults with primary CNS tumors. Between January 2007 and December 2017, primary CNS tumors 947 pts with were treated in our radiation therapy department. According to 2016 WHO CNS classification 22% LGG. MRI imaging follow-up was assessed 1-3 months after RT. The protocol included T2FLAIR 3D, T13D before and after gadolinium and perfusion weighted-imaging T2∗ (which measures cerebral blood volume-CBV). RESULTS: We present 7 pts with LGG diagnosis who underwent surgery/biopsy, molecular features were 57% codeletion 1p19q and 72% IDH1 mutation. MRI alterations observed were increased T2FLAIR and 57% pts enhancement in T1 after gadolinium both in PP and TP but in one with PP the CBV was reduced whereas in the other patients with TP it was increased. CONCLUSION: MRI is very useful in the follow up of LGG and advanced techniques such spectroscopy and perfusion-weighted help distinguish PP from TP.