Study On The Application Of Oral 2.5% Mannitol Small Intestine Contrast-enhanced Ultrasonography In Small Bowel Crohn’s Disease

Objective: To investigate the optimal time,dose and characteristics of small intestinal ultrasound imaging in patients with small intestinal Crohn’s disease(CD)after oral administration of 2.5% mannitol,and to evaluate the application value of oral 2.5%mannitol Small Intestine Contrast-enhanced Ultrasonography(SICUS)in determining the lesion site and complications of small bowel Crohn’s diseaseMethods: A total of 129 consecutive inpatients diagnosed with established CD in the Department of Gastroenterology of The First Affiliated Hospital of Fujian Medical University(Grade 3A General Hospital)from November 2019 to August 2020 were collected prospectively,29 healthy volunteers were collected,too.All the subjects underwent Intestinal Ultrasound(IUS)first,then SICUS was performed.For patients with incomplete intestinal obstruction,dynamic scanning was performed throughout the course,and for those without intestinal obstruction and healthy volunteers,the examination was occurred every 10 minutes before continuous dynamic scanning.The "flood peak effect" of each segment of the intestine showed that the best filling shape was achieved.The sonographic characteristics of small intestine in healthy volunteers and patients in CD group were observed;The time and contrast agent dosage for the whole small intestine to achieve optimal filling or optimal imaging state in CD group and in healthy group were recorded;The location and extent of CD lesions were determined;The intestinal wall thickness,hierarchical structure,intestinal wall integrity,blood flow grade,intestinal peristalsis,whether there is fat-wrapping around the intestine and whether there were complications were observed.According to the value of C-reactive protein(CRP),patients in CD group were divided into remission group(CRP ≤ 8 mg/L)and active group(CRP > 8mg/L).The clinical comprehensive diagnosis were used as reference standard,the sensitivity,specificity,positive predictive value,negative predictive value and accuracy of SICUS,IUS and Magnetic Resonance Enterography(MRE)in the detection of small intestinal location and complications in patients with CD were compared.Results:1.SICUS can be used in the whole small intestine for ultrasound imaging.For healthy volunteers,to achieve the optimal filling state,the amount of 1896 ±235.3ml oral contrast agent was needed and the best time for ultrasonic scanning was 60.8 ±5.8minutes after oral administration of contrast agent.For patients with suspected incomplete intestinal obstruction,SICUS should be peformed under dynamic tracking and scanning,and the amount of 500 ～ 1000 ml 2.5% mannitol solution should be needed.For patients without intestinal obstruction,to achieve the optimal filling state,the amount of 2121.9 ±281.1ml oral contrast agent was needed and the best time for ultrasonic scanning was 71.9 ±11.4 minutes after oral administration of contrast agent.2.SICUS,IUS and MRE have high specificity for small intestinal CD location,stricture,prestenosis dilatation,fistula and abscess,and the specificity for the whole small intestinal location were 97.9%,95.7% and 93.5%,respectively;for stricture were96.7%,98.9% and 97.8%,respectively;for fistula were 97.1%,100% and 100%respectively;for prestenosis dilatation and abscess were all 100%.3.The sensitivity of SICUS for small intestinal location in remission group was higher than that of IUS but lower than that of MRE(63.1%,34.5% and 94.1%,respectively).The sensitivity of SICUS in detecting small intestinal location in active group was higher than that of IUS and equal to that of MRE(93.1%,86.2% and 94.8%,respectively);The sensitivities of SICUS for strictures,prestenotic dilationa and intestinal fistula were higher than those of IUS and MRE :for stricture were 92.1%,36.8% and 55.3%,respectively;For prestenotic dilation were 100%,31.3% and 65.6%,respectively;For intestinal fistula were 88.9%,70.4% and 74.1%,respectively.The sensitivity of SICUS for abscess was higher than that of IUS and equivalent to MRE(93.8%,75.0% and 93.8%,respectively).4.There were statistically differences in the detection rate of SICUS and IUS in diagnosing terminal ileum lesions in remission group,strictures and prestenotic dilations(P<0.005);There were statistically differences in the detection rate of SICUS and MRE in diagnosing ileocecal lesions in remission group,stricture and prestenotic dilation(P<0.005);Compared with IUS and MRE,there were no statistically differences in detecting small intestinal lesions in active group,intestinal fistula and abscess.(P>0.05).Conclusion:1.Adequate dose of intestinal ultrasound contrast agent,data collected at the right time,real-time dynamic tracking scanning was the key to small intestine imaging of CD patients.2.SICUS significantly improved the diagnostic level of locations and complications of small intestinal CD,especially in the diagnosis of intestinal stenosis and prestenosis dilation.,but the sensitivity of SICUS to some lesions in remission stage were still lower than MRE.3.SICUS is a safe、non-invasive、inexpensive and easily tolerated examination technique,which can be used as a first-line examination technique in patients with small intestinal CD.The combination of real-time dynamic characteristics of SICUS and the intuitive image of MRE can play a complementary role in the evaluation of small intestinal CD.