Computed Tomography–Based Analysis of External Jugular Vein Cross–Sectional Area for Vascular Access in Cats

Abstract

This study evaluated the cross-sectional area (CSA) of the external jugular vein (EJV) in cats using computed tomography (CT) and assessed its correlation with body weight. Additionally, the angles between the EJV and cranial vena cava (CrVC) were evaluated. Methods This retrospective study analyzed post-contrast CT scans of 27 cats. The CSA of the EJVs was measured at the level of the cricoid cartilage using multiplanar reconstruction, and the angles between each EJV and the CrVC were assessed. Comparisons of EJV CSA and EJV-CrVC angles were performed using paired t-tests and equivalence testing with two one-sided test procedures at a 10% equivalence margin. The correlation between EJV CSA and body weight was evaluated using Pearson's correlation coefficient. Intraobserver and interobserver variability were assessed using intraclass correlation coefficients. Results Mean CSA of the left and right EJVs was 7.06 ± 3.32 mm² and 6.81 ± 3.26 mm², respectively. Mean angles between EJVs and CrVC were 154.9 ± 8.58° and 152.5 ± 10.71°, respectively. No statistically significant differences were observed between sides, and clinical equivalence was confirmed within a 10% equivalence margin. EJV CSA demonstrated a significant moderate positive correlation with body weight. Intraobserver and interobserver variability for both CSA and angle measurements were excellent. Discussion No significant morphological differences were identified between the left and right EJVs in cats, suggesting that both sides may be considered equivalent for vascular access. Furthermore, because EJV CSA shows only a moderate correlation with body weight, imaging-based evaluation is recommended for optimal catheter size selection.