ESTRO 2022 - Abstract Book

S819

Abstract book

ESTRO 2022

Conclusion This is the first exploratory clinical study to demonstrate that the dose to the left amygdala correlated with memory outcomes. This study provides further opportunities to explore the dose-volume parameters of the amygdala and definitive constraints can be used along with the hippocampus to preserve memory function following RT.

OC-0928 Dedicated SRS imaging improves brain metastases detection and reduces the intracranial relapse risk

R. Kotecha 1 , T. Kutuk 2 , K.J. Abrams 3 , M.C. Tom 2 , H. Appel 2 , M.D. Hall 2 , R. Tolakanahalli 2 , D.J.J. Wieczorek 2 , M.W. McDermott 4 , M.S. Ahluwalia 5 , M.P. Mehta 2 1 Miami Cancer Institute, Baptist Health South Florida, Radiation Oncology, Miami , USA; 2 Miami Cancer Institute, Baptist Health South Florida, Radiation Oncology, Miami, USA; 3 Miami Cancer Institute, Baptist Health South Florida, Diagnostic Radiology, Neuroradiology, Miami, USA; 4 Miami Cancer Institute, Baptist Health South Florida, Neurosurgery, Miami, USA; 5 Miami Cancer Institute, Baptist Health South Florida, Medical Oncology, Miami, USA Purpose or Objective Primary stereotactic radiosurgery (SRS) is increasingly being utilized for patients with brain metastasis, yet the risk of distant intracranial failure continues to be the principal disadvantage of this focal therapeutic approach. The objective of this study was to determine if advanced dedicated treatment planning images at the time of SRS would improve individual lesion detection and consequentially reduce the perceived rate of intracranial relapse. Materials and Methods Patients treated with SRS for brain metastasis at a single tertiary care institution underwent dedicated treatment planning MRIs including a high-resolution three-dimensional (3D) magnetization-prepared rapid acquisition with gradient echo (MPRAGE) sequence as well as an optimized 3D fast/turbo SE sequence (sampling perfection with application-optimized contrasts using different flip angle evolutions [SPACE]) from 2020-2021. Distant intracranial failure was calculated using the Kaplan-Meier method and comparisons were made to a retrospective cohort of patients treated with MPRAGE images alone for treatment planning. Results 134 patients underwent 170 courses of SRS for 821 brain metastases imaged with both dedicated treatment planning sequences from 02/20 to 01/21. Only 679 (82.7%) lesions were detected by neuro-radiologists on MPRAGE imaging alone; with both MPRAGE and SPACE sequences, this improved to 787 (95.9%), a 15.9% improvement in detection rate; an additional 34 lesions, 4.1% were confirmed by multi-disciplinary review of both imaging sequences with neuro-radiology, neurosurgery, and radiation oncology at the time of treatment. For the 142 (17.3%) lesions not detected on MPRAGE alone, the median metastasis size was 2.8 mm (Range: 0.7-6.6 mm). These were categorized into 5 classifications: 57 (40.1%) were located on a gyrus; 51 (35.9%) were located within 3 mm of a cortical vessel; 29 (20.4%) were within 5 mm of the external brain contour; 23 (16.2%) were within 3 mm of a venous sinus; and 23 (16.2%) were within 3 mm of enhancing dura. On comparison to a cohort of consecutive historical patients (103 patients, 133 SRS courses, 479 brain metastases) treated between 02/19 and 01/20 with SRS based on planning using MPRAGE sequences only, patients treated using MPRAGE with SPACE images had improved median time to distant intracranial failure (13.5 vs. 5.1 months, p<0.005). The benefit was even more pronounced for patients treated for their first course of SRS (18.4 vs. 6.3 months, p<0.001).