Abstract AIMS Arterial spin labelling (ASL) is a non-invasive perfusion technique that uses endogenous contrast and is proving to be of value in paediatric neuro-oncology. ASL derived rCBV has been shown to correlate with Dynamic Susceptibility Contrast (DSC) -derived CBV and could be an alternative perfusion technique when DSC is not possible. The aim of the study was to investigate whether early post-treatment tumour ASL can stratify patient survival at 12 months. METHOD 180 consecutive patients diagnosed with glioblastoma and undergoing treatment between 2017-2021 were imaged with an extended MRI protocol that included pseudo-continuous ASL (pCASL). Patients that were imaged with pCASL within 1-3 months of completing radiotherapy were identified retrospectively. Scanner generated Perfusion weighted images were inspected and regions of interest encompassing the tumour were generated and compared with a control region in the contra-lateral grey matter. Overall survival data was collated and a comparison of tumour ASL was assessed with t-test statistics between patients surviving < and >12 months. RESULTS 43 patients were identified (23 male, median age 58 years, diagnoses: IDHwt-GBM 17, IDHmut-Astrocytoma 13, IDHmut 1p19q co-deleted Oligodendroglioma 13). Tumour ASL was 3.22 (± 2.1) in patients that survived less than 12 months compared to 1.64 (± 1.9) in patients that survived greater than 12 months, p=0.02). CONCLUSION Early post-treatment ASL can stratify patient survival at 12 months and show promise as an alternative to DSC perfusion in the prognostication of patients being treated for glioma.