Prolonged Venous Transit on Perfusion Imaging: An Evolving Marker of Outcomes in Large Vessel Occlusion Stroke – A Comprehensive Review

Stroke remains a leading cause of death and disability worldwide, with anterior circulation large-vessel occlusion (AIS-LVO) representing a major contributor. While arterial parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and time-to-maximum (Tmax) have traditionally been used to assess perfusion, they often fail to capture microvascular dysfunction following mechanical thrombectomy (MT). Emerging evidence highlights venous outflow (VO) parameters, particularly prolonged venous transit (PVT), as reliable predictors of functional outcomes. PVT, defined as delayed opacification (Tmax ≥ 10 s) of major dural venous sinuses on perfusion imaging, reflects impaired microcirculatory drainage and tissue hypoxia. Studies have demonstrated strong interobserver agreement and consistent associations between PVT+ status and worse NIHSS scores, larger infarct volumes, higher mortality, and poor 90-day modified Rankin Scale outcomes. Compared with arterial metrics, PVT offers superior prognostic performance and can complement established VO scores such as COVES, PRECISE, and CVO. Despite study heterogeneity, current evidence supports PVT as a simple, reproducible, and clinically meaningful biomarker. Standardization of PVT measurement and integration into multimodal prognostic models could refine post-recanalization risk stratification, guide adjunctive therapies, and improve patient outcomes in acute ischemic stroke.ABBREVIATIONS: AIS LVO - Acute Ischemic Stroke due to Large Vessel Occlusion; PVT - Prolonged Venous Transit; LOS - Length of Stay; COVES - Cortical Vein Opacification Score; PRECISE - Predicting Recanalization Effectiveness in Cortical Intravenous Sinus Embolism; CVO - Comprehensive Venous Outflow score; HIR - Hypoperfusion Intensity Ratio; SSS - Superior Sagittal Sinus.