Correlation Between the Portal Venous Wall Shear Stress Using Ultrasound Vector Flow Imaging and Liver Regeneration...

This study aimed to quantitatively assess portal venous wall shear stress (WSS) using ultrasound vector flow imaging (V FLOW) in rat models with different degrees and sites of portal vein stenosis (PVS), and to investigate the relationship between V FLOW-derived WSS parameters and liver regeneration.

Seventy-five male Sprague-Dawley rats were assigned to a partial hepatectomy (PH) group (n = 15) or to moderate and severe PVS groups (PVS_M and PVS_S, n = 30, respectively). PVS was induced at either the hilum or non-hilum site (n = 15, respectively). All rats underwent 70% PH, followed by stenosis induction in the PVS groups. Portal venous WSS was measured using V FLOW pre-operatively and on post-operative days 1, 2, 3, 7, and 14. In PVS rats, WSS at pre-stenotic (WSS_pre) and post-stenotic segments (WSS_post) was obtained, and a WSS ratio (WSSR = WSS_post/WSS_pre) was calculated. Rats were sacrificed at corresponding timepoints for liver regeneration rate (LRR) and proliferating cell nuclear antigen (PCNA) assessment. Temporal changes in WSS, LRR, and PCNA were compared, and correlations of WSS with LRR and PCNA were analyzed.

A total of 60 rats with moderate or severe PVS were successfully established, with PVS ratios of 56.57% ± 3.50% and 68.21% ± 1.89%, respectively. Liver regeneration decreased with increasing stenosis severity, and LRR in the PVS_S group was significantly lower than those in the PVS_M and PH groups on post-operative days 7 and 14 (p < 0.05). The PCNA expression in the PVS_S group was significantly lower than that in the PVS_M group. V FLOW yielded stable WSS measurements across PVS types. In PVS rats, WSS_pre decreased significantly by day 7, while WSS_post increased during the first 3 days. In PVS_M, hilum stenosis resulted in lower WSS_pre and higher WSSR compared with non-hilum stenosis (p < 0.05). Both WSS_post and WSSR showed significant negative correlations with LRR (r = -0.60 and -0.572, p < 0.05) and PCNA (r = -0.558 and -0.534, p < 0.05). WSSR demonstrated the best diagnostic performance for LRR and PCNA expression, with area under the curves (AUCs) reaching 0.813 and 0.907, respectively.

Portal venous WSS_post and WSSR detected by V FLOW in PVS are negatively correlated with the LRR and PCNA, suggesting that WSS has potential value in non-invasive evaluation of liver regeneration.