CTLA4 and neoplasm: However, counterintuitively, VEGFA expression was not associated with mean or median BOLD parameters and negatively associated with ΔR1, which suggests absence of correlation between MRI-measured hypoxia and expression of VEGFA. The underlying physiology of the negative correlations between tumour perfusion and CTLA4 and CD274 expression is unclear and needs to be verified in a larger study.