The Experimental Study Of Contrast-enhanced Ultrasonography In Diagnosis Of Acute Pancreatic Fracture And Active Bleeding Of Small Vessels Injury

Objective:â‘ To study the characteristics of different scale of pancreatic fracture using contrast-enchanced ultrasonography(CEUS).â‘¡To investigate the diagnostic value of CEUS in the detection of blunt traumatic fracture of the pancreas.â‘¢To evaluate acute pancreatic fracture grading with contrast-enhanced ultrasound (CEUS) compared with operation results.â‘£To study the value of low-mechanical index CEUS in diagnosing active bleeding of small vascular injury.Material and Methods:(1) Animal experiment:Sixty pancreatic traumatic models were made with twelve healthy pigs, following which the animals were anesthetized and laparotomized. The grading was made according the AAST standards. Then conventional ultrasonography (US) and CEUS were performed to observe the sonographic characteristics of the trauma. The CEUS grades were compared with surgical findings. (2) Ex vivo experiment:We created a model of different diameter artificial blood vessels with active bleeding; the fluid flow and flow pattern were controlled by adjustable infusion pump. According to the dose used for human body, appropriate amount of ultrasound contrast agents were injected into the model for CEUS examination.Results:1. Animal experiment:(1) CEUS showed a higher diagnostic value than conventional US in detecting acute blunt pancreatic fracture (88.3% vs.66.7%). Pancreatic fracture was displayed as three types by CEUS:â‘ inhomogeneous local enhancement of pancreatic parenchyma with obscure boundary, the pancreatic parenchyma showed no signs of separation;â‘¡fissure-like low-enhancement areas with clear boundary, the pancreatic parenchyma showed no signs of separation;â‘¢the significant signs of separation were detected in pancreatic parenchyma showed the shape as "V" and bar. (2) One case was accompanied by active bleeding and showed the shape of contrast agents as brook-like. (3) The coincidence of CEUS acute pancreatic fracture grading compared with surgical findings was 96.7%(29/30) which had good grading concordance (P=0.000).2. Ex vivo experiment:The feature of active bleeding in CEUS was significantly different, which depended on diameter of artificial vessels and speed of flow. The pattern of active bleeding with high speed and pulsation was jet-like while the pattern of active bleeding with low speed was bubble-like, spot, cloudy-like in CEUS. The speed of active bleeding had significant positive correlation with the length and intensity of fluid (r=0.9397,p=0.000; r=0.9480,p=0.000).Conclusions:CEUS showed a higher diagnostic value than conventional US in detecting acute blunt pancreatic fracture and can improve the diagnostic value of ultrasound for the detection of pancreatic trauma. CEUS grading showed a high level of agreement with surgical findings. CEUS can accurately reflect the degree of acute pancreatic fracture and have important clinic application value. Meanwhile, CEUS can significantly display active bleeding, and the shape of bloodstream can reflect the pattern of active bleeding.