ESTRO 2021 Abstract Book

S472

ESTRO 2021

Results We found significant decreases in 18 F-FDG brain metabolism after PCI in basal ganglia (1.40±0.12 vs 1.34±0.13, p=0.004), central regions (1.34±0.13 vs 1.29±0.12, p=0.001), cingulate cortex (1.33±0.11 vs 1.25±0.13, p<0.001), corpus striata (1.42±0.12 vs 1.36±0.14, p=0.003), frontal cortex (1.24±0.14 vs 1.27±0.13, p<0.001), parietal cortex (1.36±0.15 vs 1.30±0.12, p=0.001), the occipital (1.50±0.15 vs 1.44±0.15, p=0.002), precuneus (1.48±0.15 vs 1.42±0.14, p=0.001), lateral temporal cortex (1.35±0.12 vs 1.29±0.11, p=0.001) and cerebellum (1.27±0.10 vs 1.23±0.09, p<0.001). Conversely, there were no significant changes in the mesial temporal cortex (MTC), which includes the hippocampi (1.05±0.09 vs 1.01±0.08, p=0.09). The subgroup who received standard PCI showed a significant decrease in metabolism of the hippocampi (1.04±0.10 vs 0.98±0.08, p=0.033). In contrast, the subgroup of patients who underwent HS-PCI showed no significant variation in metabolism of the hippocampi (1.02±0.05 vs 1.01±0.08, p=0.78) (Figure 1). Mean dose to the spared hippocampi was of 12.2 Gy.

Conclusion PCI induced a diffuse decrease in 18 F-FDG brain metabolism. HS-PCI preserves metabolic activity of the hippocampi. A 50% decrease in dose to the hippocampi is sufficient to preserve their metabolic activity.

PH-0607 Intra-arterial bevacizumab after blood-brain barrier disruption for refractory radiation necrosis S. Dashti 1 , R. Kadner 2 , B. Folley 3 , J. Sheehan 4 , D.(. Han 5 , R. Kryscio 6 , M. Carter 7 , L. Shields 8 , B. Plato 9 , R. La Rocca 10 , A. Spalding 11 , T. Yao 12 , J. Fraser 13 1 Norton Neuroscience Institute, Cerebrovascular & Endovascular Neurosurgery, Louisville, Kentucky, USA; 2 DXP Imaging, Neuroradiology, Louisville, Kentucky, USA; 3 Norton Neuroscience Institute, Norton Healthcare, Clinical Neuropsychology, Louisville, Kentucky, USA; 4 University of Virginia, Department of Neurological Surgery, Charlottesville, Virginia, USA; 5 University of Kentucky College of Medicine, Department of Neurology, Lexington, Kentucky, USA; 6 University of Kentucky, Department of Statistics, Lexington, Kentucky, USA; 7 Doctor Talk LLC, Scientific Writing/Editing, Louisville, Kentucky, USA; 8 Norton Neuroscience Institute, Norton Healthcare, Neurosurgery, Louisville, Kentucky, USA; 9 Norton Neuroscience Institute, Headache Medicine, Neurology, Louisville, Kentucky, USA; 10 Norton Cancer Institute, Norton Healthcare, Precision Medicine, Louisville, Kentucky, USA; 11 Norton Cancer Institute, Norton Healthcare, Radiation Oncology, Louisville, Kentucky, USA; 12 Norton Neuroscience Institute, Norton Healthcare, Endovascular and Cerebrovascular Neurosurgery , Louisville, Kentucky, USA; 13 University of Kentucky Cerebrovascular, Endovascular, and Skull Base Surgery, Departments of Neurosurgery, Neurology, Radiology, and Neuroscience, Lexington, Kentucky, USA Purpose or Objective This was a Phase II, multi-center, single-arm, open-label prospective clinical trial which we piloted with 10 adult patients diagnosed with medically refractory radiation necrosis of the brain. Our purpose was to evaluate the safety and efficacy of a single treatment of targeted low dose intra-arterial (IA) bevacizumab following osmotic blood-brain barrier disruption (BBBD) in adults with medically refractory brain radiation necrosis (RN). Materials and Methods After ethics board (IRB) approval and written informed consent,10 adults 35.1 ± 14.8 years of age from 2 study sites underwent blood-brain barrier disruption with 25% mannitol followed by a single targeted 2.5 mg/kg IA dose of bevacizumab. Volumes (cm 3 ) of vasogenic edema and RN were quantified at baseline, 3- and 12- months via MRI imaging. Headache, steroid dependency, functional status and neurocognitive ability were also quantified. Data expressed as mean ± SD and analyzed using Wilcoxin signed rank tests and one-way repeated measures ANOVA test of linear trend within subjects. Adverse events (AEs) were tallied. The null hypothesis was rejected for p < 0.05. Results Volume of RN decreased by 74.4 ± 14.7% (figure 1) corresponding with a significant linear trend over time [F(1) = 10.940, n = 8, p = 0.013, partial eta squared = 0.610] (figure 2, top). Vasogenic edema decreased by 50.1 ±