Application Of Ultrasound In The Follow-up Of Endovascular Aneurysm Repair

Background: With the aging population,the improvement of people's living standards and the rapid development of imaging examination technology,the incidence and detection rate of abdominal aortic aneurysms have increased.Treatment methods for abdominal aortic aneurysms include open repair and endoluminal repair.For patients with appropriate anatomical conditions and acceptable life expectancy,endovascular repair is the preferred treatment.Although endovascular aneurysm repair(EVAR)is less invasive and has lower perioperative mortality than open repair,complications of EVAR are common,mainly including access artery complications,endoleaks,stent displacement and stent-graft stenosis.Complications of access arteries include hematoma,iliac aneurysm or dissection,internal or external iliac artery stenosis or occlusion.Imaging methods for postoperative follow-up include CT angiography(CTA),magnetic resonance angiography(MRA),digital subtraction angiography(DSA)and ultrasound.CTA is the main way to detect complications,but repeated short-term review results in patients receiving excessively high cumulative radiation dose.MRA is suitable for patients who are allergic toiodine contrast agents.However,the image quality is greatly affected by the stent material,and the price increases the economic burden of patients.DSA is more accurate in diagnosing complications,and it can also carry out corresponding interventional treatment,but it is an invasive examination,which needs to comply with the indications and cannot be widely used.Ultrasound examination has the advantages of no radioactivity,economical and cheap,easy operation,and ultrasound enhancer without liver and kidney toxicity.Therefore,this study analyzed the application of ultrasound in the follow-up after EVAR.Chapter OneObjectives: To explore the value of ultrasound in the follow-up after EVAR.Methods:To collect clinical data,imaging examination(CTA,DSA,ultrasound)data and postoperative complications of patients undergoing EVAR admitted to the First Affiliated Hospital of Chongqing Medical University from January 2013 to September 2018.Comparative analysis of ultrasound and CTA to explore the value of ultrasound in the diagnosis of complications.Results: 246 patients were followed up regularly on postoperative imaging,including 162 cases with CTA examination,29 cases with endoleak detection,55 cases with internal or external iliac artery stenosis or occlusion,22 cases with stent lumen stenosis,20 cases with postoperativeiliac aneurysm or dissection,hematoma 34 cases,1 case with stent retraction;25 cases with DSA examination,12 cases with endoleak detected,3 cases with internal and external iliac artery stenosis and occlusion,6 cases with stent lumen stenosis,6 cases with postoperative iliac aneurysm or dissection,and 1 case with hematoma,1 case with stent retraction;189 cases with ultrasound,40 cases with endoleak detected,5cases with internal or external iliac artery stenosis or occlusion,18 cases with stent lumen stenosis,25 cases with postoperative iliac aneurysm or dissection,30 cases with hematoma,One case of stent overlap and one case of stent retraction.246 patients underwent 120 simultaneous CTA and ultrasound examinations,and 25 underwent simultaneous ultrasound,CTA and DSA examinations.Among 120 patients who underwent CTA and ultrasound examination at the same time,the number of endoleaks detected by CTA and ultrasound were 36 and 33 respectively,58 and 17 were internal or external iliac artery stenosis or occlusion,and 21 and 18 were stent lumen stenosis.There were 20 cases,25 cases of iliac aneurysm or dissection,34 cases and 29 cases of hematoma,and 1 case of stent retraction.Compared with CTA,ultrasound detected endoleak,stent lumen stenosis,postoperative iliac The accuracy rates of aneurysm or dissection and hematoma formation were 89.2%,94.2%,80.8% and 94.2%,the missed diagnosis rates were 22.2%,23.8%,45.0% and 17.6%,and the misdiagnosis rates were 6% and 2.2% respectively,14.0% and 1.2%,theaccuracy rate of detecting internal and external iliac artery stenosis or occlusion is 51.7%,the missed diagnosis rate is 83.6%,and the misdiagnosis rate is 11.9%.In the detection of stent retraction,because the number of cases is too small,No statistical analysis was done.Of the 25 patients who underwent ultrasound and DSA examinations at the same time,10 cases and 12 cases of endoleaks were detected by ultrasound and DSA,1 and 3 cases of internal and external iliac artery stenosis and occlusion,and 6 and 6 cases of stent lumen stenosis.5 cases and 6 cases of posterior iliac aneurysm or dissection,1 case of hematoma and 1 case of stent retraction;compared with DSA,ultrasound detected endoleak,stent stenosis and postoperative iliac aneurysm or dissection The accuracy rates were 84.6%,100%,and 83.3%,and the missed diagnosis rates were 16.7%,0,and 16.7%,respectively.There were no misdiagnosed cases.In the detection of stenosis and occlusion of the internal and external iliac arteries,stent retraction and hematoma,no statistical analysis was performed because the number of cases was too small.Conclusion: 1.Compared with CTA,ultrasound has higher accuracy in detecting endoleaks,stent lumen stenosis,postoperative iliac aneurysms or dissection,and hematoma;ultrasound has lower accuracy in detecting internal or external iliac artery stenosis or occlusion.2.Compared with DSA,ultrasound has higher accuracy in detecting endoleak,stent lumen stenosis,and postoperative iliac aneurysm ordissection.3.Due to the advantages of non-invasive,cheap,repeatable and high accuracy,ultrasound can become the main method of follow-up after EVAR.Chapter twoObjective: To summarize the ultrasound manifestations of postoperative complications of EVAR and analyze the causes of misdiagnosis of ultrasound.Methods: 121 patients who underwent CTA,ultrasound,DSA and ultrasound at the same time after surgery were selected to summarize and analyze the ultrasound findings of endoleak,stent lumen stenosis,postoperative iliac aneurysm or dissection,and hematoma Analyze the cause of misdiagnosis of ultrasound.Results: The ultrasound manifestations of endoleaks mainly include: 1.AAA are more enlarged than before surgery(mainly the increase in transverse diameter),and there is a long strip of low echo between the abdominal aortic wall and the stent.There is no echo in the flake,2.Red and blue blood flow signals are seen in the small no-echo.3.The blood flow in the lumen of the abdominal aorta flows through the upper or lower end of the stent into the echo between the abdominal aortic wall and the stent(Type I Endoleak);thin strips of blood flow through the wall of the abdominal aorta at the anuerysm and into the echo-free space between the wall of the abdominal aorta and the stent(type II endoleak);intraluminal blood flow in the abdominal aorta(intra-stent blood flow)through the stent wall.It flows into the echoless wall between the abdominal aortic wall and the stent(type III endoleak),and the width of the colored blood flow across the stent wall is 1mm-2mm.Type ? blood can be derived from inferior mesenteric artery,lumbar artery,internal iliac artery and so on.Ultrasound manifestations of stent lumen stenosis are as follows: 1.The diameter of the stent is thinner,its internal sound transmission is good or there is a point-like low echo,2.The color blood flow beam in the stent is narrowed,or a little dim point-like blood flow signal is seen.The blood flow signal cannot even be detected.3.The flow rate of the narrowed color blood flow beam is increased,and the sampling of the dim point blood flow signal shows a low-speed venous-like spectrum.The ultrasound manifestations of the iliac aneurysm or dissection after operation are mainly as follows: 1.Banded medium-strong echoes are seen in the iliac artery cavity,the iliac artery is divided into two lumens,or the local diameter of the iliac artery is "fusiform" expansion,2.The true cavity and the false cavity see blood flow injection or no blood flow signal in the false cavity,and red and blue alternating blood flow signals are seen in the dilated blood vessel lumen.The ultrasound manifestations of hematoma are as follows: 1.Abnormal echo in the common iliac artery or around the middle and lower segments of the abdominal aorta or in the soft tissue of the groin area.The boundary is not clear and the shape is irregular.The main cause is low echo.2.No blood flow signal.Compared with the detection results of CTA or DSA,the number of missed ultrasound diagnosis and misdiagnosed endoleak cases were 8 and 5 respectively,stent lumen stenosis was 5 and 2 cases,and postoperative iliac aneurysm or dissection formed 9 and 14 cases.There were 6 cases of hematoma and 1 case.The main reasons were as follows: 1.The source of the blood flow signal between the abdominal aortic wall and the stent was not carefully observed.2.Conventional ultrasound was difficult to observe the low-speed and low-flow blood flow.3.No attention was paid to the abdomen.Signs of aortic aneurysm expansion and stability,4.Intestinal gas,atherosclerotic plaque on the arterial wall and scaffold strong comet tail signs interfere with ultrasound sonogram,5.Beginners or those with insufficient diagnostic experience,6.Ultrasound instrument condition adjustment is not good.Conclusion: Ultrasound manifestations of endoleak,stent lumen stenosis,postoperative iliac aneurysm or dissection,and hematoma are complex and diverse,but they have certain specificity.For more typical cases,the ultrasound manifestations still have certain characteristics.Although the accuracy of ultrasound diagnosis in typical cases is high,for cases with atypical performance,novices or inexperienced persons are not carefully observed during the scan or the machine conditions are poorly adjusted,and missed or misdiagnosed cases may occur.If you pay attention to accumulating experience during postoperative follow-up,observe carefully,and pay attention to instrument adjustment,you can avoid missed and misdiagnosed parts of patients and improve the accuracy of ultrasound diagnosis.