Evaluation of 4D Flow MRI‐Derived Relative Residence Time as a Marker for Cirrhosis Associated Portal Vein Thrombosis

Background Portal vein thrombosis (PVT) is thought to arise from stagnant blood flow, yet conclusive evidence is lacking. Relative residence time (RRT) assessed using 4D Flow MRI may offer insight into portal flow stagnation. Purpose To explore the relationship between RRT values and the presence of PVT in cirrhotic participants. Study Type Prospective. Population Forty‐eight participants with liver cirrhosis (27 males, median age 67 years [IQR: 57–73]) and 20 healthy control participants (12 males, median age 45 years [IQR: 40–54]). Field Strength/Sequence 3 T/4D Flow MRI. Assessment Laboratory (liver and kidney function test results and platelet count) and clinical data (presence of tumors and other imaging findings), and portal hemodynamics derived from 4D Flow MRI (spatiotemporally averaged RRT [RRT‐mean], flow velocity, and flow rate) were analyzed. Statistical Tests We used multivariable logistic regression, adjusted by selected covariates through the Lasso method, to explore whether RRT‐mean is an independent risk factor for PVT. The area under the ROC curve (AUC) was also calculated to assess the model's discriminative ability. P < 0.05 indicated statistical significance. Results The liver cirrhosis group consisted of 16 participants with PVT and 32 without PVT. Higher RRT‐mean values (odds ratio [OR] 11.4 [95% CI: 2.19, 118]) and lower platelet count (OR 0.98 per 1000 μL [95% CI: 0.96, 0.99]) were independent risk factors for PVT. The incorporation of RRT‐mean (AUC, 0.77) alongside platelet count (AUC, 0.75) resulted in an AUC of 0.84. When including healthy control participants, RRT‐mean had an adjusted OR of 12.4 and the AUC of the combined model (RRT‐mean and platelet count) was 0.90. Data Conclusion Prolonged RRT values and low platelet count were significantly associated with the presence of PVT in cirrhotic participants. RRT values derived from 4D Flow MRI may have potential clinical relevance in the management of PVT. Evidence Level 2 Technical Efficacy Stage 2