| Part one Feasibility research of aorta angiography under 1.5T magnetic resonance by using time-resolved angiography with interleaved stochastic trajectories technique.Objective:To investigate the feasibility of aorta angiography under 1.5T magnetic resonance by using time-resolved angiography with interleaved stochastic trajectories(TWIST)technique.Materials and methods:1.Clinical dataA total of 51 patients,who diagnosed as aortic disease,were selected from January 2010 to October 2015 in the xinhui people's hospital of Jiangmen city.There were 38 men and 13 women.The ages were ranged from 29 to 81 years old,the median age was 60 years.38 cases of them had sudden chest and abdominal pain,9 cases of them with chest discomfort,1 cases of them for review of post-hybrid surgery of Standford type A aortic dissection,and 3 cases of them for following up with conservative treatment of aortic dissection by Standford type B.2.Method of examinationAll the patients were performed with 1.5 T magnetic resonance scanner(Avanto;Siemens;Germany),which with seamlessly integrated coil elements,combinable to 18 radio frequency receiving.All the patients take supine,head come first,the top of xiphoid process as the center point to place the surface coil.The scan from the thoracic inlet to the pubic symphysis level.At first,To obtain the basic images of the major vessels and major organs as the location for the CE-MRA,chest and abdomen were scanned with coronal,axial and sagittal position on two-dimensional true fast imaging with steady-state precession T2WI sequence.Scanning parameters for TWIST sequence:parallel acceleration factor 2,TR-2.61ms,TE--0.94,flip angle(FA)25 degree,field of view(FOV)460×345mm,slice thinkness 1.40mm,central region A 15%,sampling density B 25%,voxel size 1.4×1.0×1.4mm3,temporal resolution 2.77 s,scanning at the same time as injecting contrast medium and without breath holding,20 phases data were collected during 62 seconds.Contrast medium was gadopentetic acid meglumine injection(Gd-DTPA,Guangzhou Kang Chen pharmaceutical),dose was 0.2mmol/Kg.NEOTO double-Syringe Injector(SHOT X;MEMOTO KYORINDO;JAPAN).30ml Gd-DTPA sent to A,15 ml physiological saline sent to B.Bolus injection through the elbow vein,the injection rate was 3.0ml/s.3.Image postprocessingPostprocessing workstation is SIEMENS MR Workplace syngo,The machine automatically subtracted mask,each phase to obtain two groups of image for the original and subtraction,all data was transfed to the workstation.Using twist syngo communicate new 4D vascular imaging software package for MIP(maximum intensity projection)and MPR(multiplanar recombinant multiplanar)to obtain desired aortic vascular image.4.Evaluation and standard of image quality2 physicians with a deputy director or above used the double blind method to diagnose the disease independently.According to three aspects to comprehensive evaluation of image grade,including whether there are pseudo shadows in the picture,the ability to display the details of the structure and the effect of arterial enhancement.The evaluation was carried out by using the grades 3 scoring method:Grades 3,the image quality is good,no movement or step artifact;Grades 2,the image quality is acceptable and can be evaluated,but still a little fuzzy;Grades 1,the image quality is poor and can not be evaluated,the image is blurred or the edge of the anatomical structure appears heavy shadow.The image is considered to meet the diagnostic needs which evaluated score of Grade 3 or Grade 2.5.Statistical analysisAll data was analysised by using SPSS 19.0(SPSS,Chicago,IL,USA)statistical software.The consistency of image quality assessment by two doctors was compared and analyzed using Cohen's k-test.K-Value of 0.21-0.40 corresponded to bad agreement,K-Value of 0.41-0.6 corresponded to moderate agreement,K-value of 0.61-0.80 corresponded to good agreement,and 0.80-1.00 corresponded to perfect agreement.Result:1.All of 51 patients successfully completed the MRI examination.The rate of success was 100%.All patients without adverse reactions.2.All patients were obtained from 13 to 15 pieces arterial phase images.Two doctors independently analyzed each period of the images,and then comprehensive evaluated the image quality,and finally achieved image quality grade scores.The average scores were grades 2.96 and grades 2.94.The evaluation results were excellent consistency(Kappa value =0.70).All image evaluation scores was higher than Grades 2 whice considered meeting the diagnostic needs.3.Compared with surgery and/or comprehensive examination,the diagnostic accuracy rate was 100%in 51 patients.There were normal aorta in 16 cases,aortic dissection in 18 cases,aortic intramural hematoma in 3 cases,Penetrating atherosclerotic ulcers in 2 cases,aortic aneurysm in 2 cases,aortic sclerosis in 4 cases,and aortic stenosis in 1 cases.1 case was Standford A type aortic dissection for reviewed after surgery.3 cases were Standford B type aortic dissection for conservative treatment follow-up.Conclusion1.1.5T magnetic resonance MRA using TWIST technology in aortic is feasible,with the help of temporal resolution improvement,scanning speed is faster.Patients do not need to hold breath,operators do not need to estimate the scan time,which reduce the technical requirements of inspection.2.13 to 15 arterial phases images can be obtained on each scanning,and all the image can meet the diagnostic requirements.3 Magnetic resonance imaging has no radiation hazard,whice is suitable for the application with aortic disease in patients who need regular follow-upPart two Application value of 1.5T magnetic resonance angiography using TWIST technique in diagnosing aortic dissectionObjective:To investigate the application value of 1.5T magnetic resonance angiography using time-resolved angiography with interleaved stochastic trajectories(TWIST)technique diagnosing aortic dissectionMaterials and methods:1.Clinical dataA total of 36 patients diagnosed as aortic disease were divided into a control group and a research group according to the order of inspection in xinhui people's hospital of Jiangmen city from December 2010 to January 2016.18 patients in each group.2.Method of examinationScanning parameters as the first part such as examination equipment used by the two groups of patients,the scanning position,plain scan and contrast agent dose,injection method and the research group MRA.18 cases of control group,CE-MRA using coronal ultra fast 3D gradient echo sequence.Scanning parameter:TR-2.90ms,TE-1.OOms,flip angle was 25 degrees,field of view(FOV)390mm x 330mm,slice thickness 1.30mm,with zero dead time acquisition,breath holding in 21s to gain an arterial phase data,using MR real-time method to determine the delay time for scanning.3.Image postprocessingThe raw data by scanning was transferred to Siemens workstation(syngo MR workplace),the TWIST syngo new communication 4D vascular imaging software package for maximum intensity projection(MIP(maximum intensity projection,MIP)and multiplanar recombinant(multiplanar reconstruction,MPR),achieved the aorta image.4.Evaluation items and diagnostic standard2 physicians with a deputy director or above used the double blind method to diagnose the disease independently,Evaluation the following details:(1)The research group and the control group of image quality:according to three aspects to comprehensive evaluation of image grade,such as whether there are pseudo shadows in the picture,the ability to display the details of the structure and the effect of arterial enhancement.The evaluation was carried out by using the grades 3 scoring method:Grades 3,the image quality is good,no movement or step artifact;Grades 2,the image quality is acceptable and can be evaluated,but still a little fuzzy;Grades 1,the image quality is poor and can not be evaluated,the image is blurred or the edge of the anatomical structure appears heavy shadow.If the image evaluation score of Grades 3 or Grades 2,is considered to meet the diagnostic needs.(2)Type of AD.According to the Stanford classification method is divided into 2 types.Type A:Intimal tear can be in the ascending aorta,aortic arch and descending aorta proximal,It can involve the ascending aorta or aorta arch,can also be extended to the descending aorta or abdominal aorta.Type B:Intimal tear often located at the aortic isthmus,extended only involved in descending aorta or extending to the abdominal aorta,but not involving the ascending aorta.(3)The position and size of the initial tears,re-entry tears position and are there any more multiple break.(4)The morphology of the true and false lumen and intimal flap.(5)The branches of the aorta(including anonyma,left common carotid artery,left subclavian artery,celiac trunk artery,superior mesenteric artery,bilateral renal artery,bilateral common iliac artery,internal iliac artery and external iliac artery).(6)Whether there is thrombosis in the false lumen.(7)Compare the advantages and disadvantages in two method(MPR and MIP)to display the details of the lesion in postprocessing.(8)The contrast agent signal intensity changes were observed in the reasearch group,and the filling time(Ts),the contrast agent peak time(Tp),and the contrast contrast agent degrade(Td)were recorded.Hemodynamic changes in response to these indexes.5.Statistical analysisAll data was analysised by using SPSS 19.0(SPSS,Chicago,IL,USA)statistical software.A value of P<0.05 was considered statistically significant.All characteristics data was expressed as mean±standard deviation.Two independent samples t-test was used in comparing measurement data.Pearson chi-square test was performed enumeration data between two group.The consistency of image quality assessment by two doctors was compared and analyzed using Cohen's k-test.and K-Value of 0.21-0.40 corresponded to bad agreement,K-Value of 0.41-0.6 corresponded to moderate agreement,K-value of 0.61-0.80 corresponded to good agreement,and 0.80-1.00 corresponded to perfect agreement.Result:1.Basic clinical dataThe research group:there were 15 males(83.3%)and 3 females(16.7%),average age was 63.8±12.5 years old.The control group:there were 13 males(72.2%)and 5 females(27.8%),average age was 64.0± 13.9 years old.There was no significant difference in gender and age between the two groups.36 cases of patients with duration of 3 hours to 5 years.Acute(within 2 weeks)of 25 cases.Chronic(disease more than 2 weeks)11 cases.In 29 cases(80.6%),it showed a sudden severe pain in the chest,and extended to the chest and back,upper left arm or abdomen.In 6 cases(16.7%),chest distress was not well.1 cases(2.7%)had no obvious symptoms.There were 32 cases of hypertension(90%):grade I(BP 141?159mmHg)8 cases,grade ?(BP 160?179mmHg)12 cases;grade ?(BP>180mmHg)12 cases.2.1mage quality comparisonBoth the image quality score in two groups was higher than 2 grade,it meet the diagnostic requirements.The difference between the research group and the control group was not statistically significant.Two physicians evaluated the aortic image quality of the two groups of patients,with a high consistency(Kappa Value was 0.77 and 0.82 in research group and control group).3.Types of aortic dissectionThe research group:3 cases in Standford type A;15 cases in type B;The control group:2 cases in type A,16 cases in type B.1 case of research group as type A provided by surgery,6 case of research group determined through DSA or CTA as type B.The diagnosis accurate rate is 100%(7/7).4.The location and number of tearsIn the research group,18 cases were able to clearly show the initial rupture and the contrast agent into the false lumen.Among them,2 cases were located at the root of ascending aorta,1 cases were located in the aortic arch,10 cases were located at the junction of aortic arch and descending aorta,2 cases were located in the lower part of the thoracic aorta,3 cases were located in the abdominal aorta,the width of rupture was from 3mm to 10mm.7 cases were reentrance in the iliac artery,and 9 cases in the abdominal aorta,1 cases in thoracic aorta and ascending aorta.In the control group,15 cases can clearly show the initial rupture port.3 cases failed to find the initial rupture position.The initial rupture of the aorta was located in the middle of the ascending aorta in 2 cases.8 cases were located at the junction of aortic arch and descending aorta.5 cases were located in the abdominal aorta,the width of rupture was from 3mm to 8mm.5 cases were reentrance in the iliac artery,6 cases in the abdominal aorta,and 1 cases in Descending aorta.6 cases could not find the re entrance location,because of the low contrast of the false lumen.5.The ntimal flap of dissection and the morphology of true lumen and false lumen36 cases were able to clearly show the tear film,which showed a linear low signal shadow in the blood vessel lumen,and MPR showed more clearly.The true and false lumen of aortic dissection can be relatively parallel or spiral walk,or false cavity spiral enlace true lumen.The true lumen often shows smaller than false lumen,most of them was semi-circular or oval;The false lumen is larger,it was semicircular or crescent.6.Hemodynamic changes of the true and false lumen of aortic dissection:The research group cases adopted continuous multi period imaging.True lumen Ts=(23.7 + 4.4)s,Tp=(30.6±5.0)s,Td=(36.8±4.8)s.False lumen Ts=(26.7 + 4.5)s;Tp=(36.1 + 5.3)s;Td=(42.4 + 5.9)s.The results show the true lumen opacification and contrast agent disappeared were earlier than the false lumen.The difference was statistically significant(P<0.05).The single phase scan of the control group was unable to evaluate the hemodynamic changes of the two cavities in aortic dissection.7.The aortic branch involvement3 patients of the research group with type A dissection,1 case for innominate artery involvement,1 case for left subclavian artery involvement.Among the 15 cases with Type B aortic dissection,1 case had celiac trunk artery involvement,2 cases involved superior mesenteric artery,2 cases had renal artery involvement(1 patient in the left and 2 patients in the right),3 cases involved in the common iliac artery(1 patient in the left and 2 patients in the right).The control group of 16 cases for type B dissection,coeliac trunk artery was involved in 1 cases,1 cases of superior mesenteric artery involvement,2 cases of renal artery(1 case on the left,1 case on the right),2 cases of iliac arteries(1 case on the left,1 case on the right).In the research group,the details of the involvement of the branch vessels can be clearly displayed by using multiple phase images,which can be confirmed by each other,so as to avoid the incomplete evaluation.8.Thrombus in the false lumen.In 36 cases,30 cases had no obvious intraluminal thrombosis,6 cases of intraluminal thrombus formation,including 3 cases in the experimental group,3 cases in the control group.9.Compare the display capabilities of the two postprocessing technologiesMPR showed better than MIP on the morphology of the rupture,tear film and True and false cavity form,the different was statistically significant(P<0.05).MIP multi angle rotation is more intuitive to show the overall situation of the aorta.Conclusion:1.5T magnetic resonance angiography using TWIST technique can reduce the examination requirement both patient and the examination operator without reducing the image quality.Multi phase image can be obtained through once scanning,with the help of the postprocessing technology can not be only display the morphological changes of aortic dissection,but also provide additional hemodynamic information.It may be the first choice of examination for the diagnosis of aortic dissection. |
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