Interobserver and Intraobserver Variability in the Assessment of Prolonged Venous Transit in Anterior Circulation Large-Vessel Occlusion Ischemic Stroke.

Background and purpose: Prolonged venous transit (PVT) on time-to-maximum (Tmax) perfusion maps has been associated with worse outcomes in patients with acute ischemic stroke due to anterior circulation large-vessel occlusion (AIS-LVO). The qualitative nature of PVT assessment introduces potential variability, and its reproducibility has not been systematically evaluated.

Materials and methods: In a retrospective study of patients with confirmed AIS-LVO, 2 board-certified neuroradiologists independently reviewed pretreatment Tmax maps to assess PVT in the posterior superior sagittal sinus and torcula. One reader repeated the assessment after 24 weeks at minimum. Interobserver and intraobserver variability were evaluated with Cohen unweighted κ coefficients.

Results: Among 194 patients, median age was 70 years (interquartile range, 62-79), and 57% were women. Interobserver agreement was substantial (κ = 0.79; 95% CI, 0.69-0.88), reflecting concordant classification in 178 of 194 patients. Intraobserver agreement was also strong (κ = 0.87; 95% CI, 0.79-0.94), with initial and repeat evaluations differing in 11 cases.

Conclusions: Qualitative PVT assessment demonstrated substantial interobserver and almost perfect intraobserver reliability. These findings support the use of PVT as a consistent marker of impaired venous outflow in AIS-LVO. Future studies should explore automated or semiquantitative methods to further improve reproducibility and enhance clinical utility.