Portal Venous Systemic Thrombosis In Early Acute Pancreatitis: An MRI Study

Objective:To study the prevalence of portal venous systemic thrombosis（PVST）in the early stage of acute pancreatitis（AP）and its correlations with the classification and severity of acute pancreatitis.Materials and Methods:A total of 396 patients with AP who were admitted to our hospital between January 2013 and May 2017 and who underwent the abdominal magnetic resonance imaging（MRI）scans within two weeks of the onset of acute pancreatitis were recruited in this study.The MRI sequences included the conventional and dynamic-enhancement sequences.The pancreatitis and the portal venous systemic thrombosis was evaluated on the T₁WI,T₂WI fat suppression and the dynamic-enhancement sequences,when patients who have a linear or patchy high signal within the venous lumen on the T₁WI or T₂WI fat suppression MR imaging that shows a segmental or completeintravenous filling defect on the enhanced venous and delayed phase images or whose vein was undetectable on the enhanced venous and delayed phase images.According to the patients’MR imaging,the clinical and laboratory tests,calculating the MR severity index（MRSI）and the revised Marshall scores,respectively.The severity of acute pancreatitis were graded by both the MR severity index（MRSI）and the New Revised Classification of acute pancreatitis 2012.The prevalence of portal venous systemic thrombosis,the severity and classification of acute pancreatitis,the hospitalization time were all been recorded.Theχ² test or Fisher exact test were used to evaluate the differences of the prevalences of portal venous systemic thrombosis among the mild,moderate/moderately severe,and severe acute pancreatitis,as well as between the interstitial edematous pancreatitis and necrotizing pancreatitis.Mann-Whitney U test was used to calculate the differences of hospitalization time between patients with the portal venous systemic thrombosis and those patients without portal venous systemic thrombosis.Results:The portal venous systemic thrombosis was detected in 30patients（7.5%,30/396）.According to the MRSI,in the mild,moderate,and severe AP,the prevalence of portal venous systemic thrombosis were,respectively,1.0%（2/205）,11.9%（21/177）,and 50%（7/14）（χ²=41.455,P=0.000）.Based on the New Revised Classification of Acute Pancreatitis2012,in the mild,moderately severe,and severe acute pancreatitis,the prevalence of portal venous systemic thrombosis were,respectively,0.0%（0/194）,13.6%（25/184）,and 27.8%（5/18）（χ²=42.130,P=0.000）.In the interstitial edematous pancreatitis and necrotizing pancreatits,the prevalence of portal venous systemic thrombosis were 3.3%（11/331）and 29.2%（19/65）（χ²=48.447,P=0.000）.The hospitalization time[Median（interquartile range）]in patients with portal venous systemic thrombosis and in those without portal venous systemic thrombosis were 18（12.8-22.3）days vs.13（10-19）days（Z=-2.913,P=0.004）.Conclusion:The portal venous systemic thrombosis in the early stage acute pancreatits presented more with the severity of acute pancreatitis based on both the MRSI and the New Revised Classification of Acute Pancreatits2012 increasing,the hospitalization time in patients with portal venous systemic thrombosis was longer.The portal venous systemic thrombosis in the early stage of acute pancreatitis might be a supplementary indicator of the severity of acute pancreatitis.