Clinical Application Of Contrast-enhanced MR Angiography In The Diagnosis Of Intracranial Aneurysms

Intracranial aneurysm is one of the most popular cerebral vascular diseases,it always lead to spontaneous subarachnoid hemorrhage,ultimately induce disability and mortality.Effective therapy was depended on early and accurate diagnosis.Now,DSA is still frequently used in the diagnosis of intracranial aneurysm,but it is expensive,time consuming,and may lead to complications and permanent neurological defect.Contrast enhanced MR angiography(CE-MRA) is a new technique used in diagnosis and treatment of cerebrovascular diseases in recent years.It is simple,noninvasive,low expense,and clearly displaying the anatomic structure of aneurysm with peripheral vessels.In this study,we used CE-MRA in the diagnosis of intracranial aneurysms and follow-up after endovascular therapy,to evaluated the clinical value of CE-MRA by comparing it with DSA.Objective:The aim of this study was to evaluated the clinical value of CE-MRA in detecting intracranial aneurysms and to determine the feasibility and usefulness of CE-MRA for the follow-up of intracranial aneurysms after endovascular therapy,by comparing with DSA,and to explore the factors correlating with aneurysms' recurrence.Subjects and methods:CE-MRA was performed with 1.5T system(Siemens Avanto),using head and neck coils,fluoroscopic triggering technique and three-dimensional fast low angle shot(3D FLASH)sequence had been used.Scan repeated three times (pre-contrast,arterial phase and venous phase).A 0.2mmol/kg bolus of contrast medium(Gd-DTPA) was injected from antecubital vein at a rate of 3ml/s by a power auto-injector.The source images of CE-MRA were subtracted and transferred to computer workstation using 3D reconstruction,reconstruction images include MIP,VR and MPR.DSA was performed with the digital subtraction angiography machine(PHILIPS Allara Xper FD20),Angiography of bilateral inner carotid and unilateral vertebral artery were performed from the right femoral artery pathway with Seldingle technique.centric position,lateral position and oblique position images were taken for both inner carotid and vertebral artery.(1)106 patients suspected with intracranial aneurysms underwent CE-MRA and DSA in the same week,among 106 patients,there were 42 males and 64 females,mean age was 55 years,age range was from 17years to 78 years.CE-MRA images were compared with conventional DSA images in detecting intracranial aneurysms to assess the sensitivity,specificity and accuracy of CE-MRA,statistical method was chi-squar test.Aneurysms were measured on two kinds of images respectively,measure value were analyzed by t test to evaluated the accuracy of CE-MRA,DSA was considered as the gold standard,the Signifcant Level of Chi-square test and t test was 0.05.(2)56 patients(27 males and 29 females,mean age,53 years;age range,27～76 years) were underwent CE-MRA and DSA simultaneously after endovascular therapy,the embolism effect of endovascular therapy was divided into three categories:complete occlusion,residual neck and incomplete occlusion.CE-MRA images were compared with DSA to calculated the sensitivity of CE-MRA in the follow-up of intracranial aneurysms after endovascular therapy.According to the aneurysms size and embolism effect,aneuryams could be devided into different group,statistical analysis was executed between each group to explore the relationship between these factors and aneurysms recurrence.the statistical method was Chi-square test(Fisher exact probobilities),the Signifcant Level was 0.05.Results:(1) there were 83 cases with 90 intracranial aneurysms,among these patients,there were 7 cases who had double aneurysms,posterior communicating artery(35.56%) was the most common location,the second was internal carotid artery(32.22%).There was no statistical difference(P＞0.05) between CE-MRA and DSA in detecting intracranial aneurysms,the sensitivity,specificity and accuracy of CE-MRA were 98.8%,82.6%and 95.58%respectively.The sizes of aneurysm can be measured on CE-MRA images accurately,compared with conventional DSA(P＞0.05).CE-MRA was superior to DSA in displaying the thrombus inside aneurysms.(2) There were 56 cases with 61 aneurysnrs underwent endovascular therapy,after embolization immediately,DSA revealed complete occlusion in 43 cases,residual neck in 15 cases,and incomplete occlusion in 3 cases,there were 9 aneurysms reoccurred during follow-up,the rate of recurrence was 14.75%.embolism effect was obviously correlated with aneurysms recurrence,compared with complete occlusion and residual neck,incomplete occlusive aneurysms(P＜0.0125) were more easy to reoccur.CE-MRA and DSA showed a good and significant agreement between techniques(κ=0.871,P＜0.005),The sensitivity of CE-MRA was 93.4%,for incomplete occlusive aneurysms,the sensitivity of CE-MRA was 100%.False-positive and false-negative were 2 cases respectively.DSA was superior to CE-MRA in displaying tiny residual neck.Large aneurysms(P＜0.001) were more easy to reoccur,and the ratio was 77.8%.Conclusion:CE-MRA is a fast,noninvasive and efficient technique for diagonosing intracranial aneurysms,it can precisely display the configuration,neck,intraluminal thrombus and anatomic connection with surrounding vessles,these 3D information is useful for treatment planning.After aneurysms endovascular therapy,CE-MRA is very effective in monitoring residual neck or aneurysms recurrence.Aneurysms recurrence were correlated with size and embolism effect strongly.