A multicenter study reports that clot perviousness, or permeability – the ability for contrast used during the initial imaging workup to seep through a clot, as estimated by CT imaging – is associated with ”first-pass success” in large vessel occlusion (LVO) strokes initially treated with an aspiration thrombectomy approach. LVO stroke treatment success using a stent retriever-first approach to remove the brain vessel blockage was less dependent on clot perviousness.