| Objective:To study the value of cardiac CT(CCT)in visual and quantitative assessment of the left atrial appendage spontaneous echo contrast(LAASEC),sensitive indicators and their ability to identify different grades of SEC.Methods:From January 2014 to June 2016,all inpatients with atrial fibrillation who received both two-phase CCT and transesophageal echocardiography(TEE)examinations were included in the study.All patients had detailed medical history,received relevant physical and laboratory examinations.Exclusion criteria for the study were:? age<18 years old,CCT and TEE check interval>10 days.? there are TEE check contraindications(active gastrointestinal bleeding,esophageal stricture)and CCT test contraindications(iodine allergy,severe renal failure,heart failure)or did not sign informed consent.? congenital heart disease,artificial mechanical valve or previous history of deep vein thrombosis and pulmonary embolism,carotid artery stenosis>50%,history of malignant tumors.? low TEE space resolution,CCT image distortion layer,breathing motion artifacts,faint contrast agent enhancement and other poor image quality.A total of 251 patients were included in the study.Among them,male(148.0%),female 103(41.0%)cases,aged 33-86 years,mean(63.1 ± 9.2)years,persistent atrial fibrillation in 111(44.2%)cases,paroxysmal atrial fibrillation patients(55.8%),hypertension 146(58.1%),left ventricular dysfunction 34(13.5%),diabetes 60(23.9%),cerebral infarction or transient cerebral ischemia 41(16.3%)cases.The interval between CCT and TEE was 1.78 ± 1.83 days.TEE was performed with a 4-7 MHz multiplanar probe positioned at the appropriate level within the esophagus(HP SONOS5500).The severity of LAASEC was classified into 0 to 4 grades on the basis of appearance and density.At the same time,Two-phase cardiac CT was performed with a 128-section helical CT unit(SOMATOM Definition Flash,Siemens Healthcare,Forchheim,German).Using TEE as the gold standard,CCT was analyzed visually by evaluating sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),and accuracy.In addition,LAA apex,left atrial body and ascending aorta(AA)attenuation(Hounsfield units)were measured on two-phase CCT to calculate LAA/AA and LAA/LA attenuation ratios.The quantitative values of LAA/AA,LAA/LA and LAA were determined on the basis of the receiver operating characteristic(ROC)curve.Results:In our study 251 patients,TEE demonstrated grade 0 LAASEC in 114 cases,grade 1 in 73 cases,grade 2 in 19 cases,grade 3 in 25 cases,grade 4 in 15 cases and LAA thrombus in 5 cases,respectively.On CCT,88 patients were found with filling defect in the early phase,of which,there were grade 0 in 8 cases and grade 1 in 16 cases,grade 2-4 were all included.CCT early and delayed period were filling defect in 5 cases,TEE are shown as thrombosis.Sensitivity,specificity,PPV,NPV and accuracy values of CCT for LAASEC(?grade 1)were 56.8%,93.0%,90.7%,65.0%and 72.1%,respectively.The sensitivity,specificity,PPV,NPV,and accuracy of CCT qualitative diagnosis of LAASEC(?grade 2)were 100.0%,87.1%,71.1%,100.0%and 88.4%respectively.The early phase CCT quantitative analysis showed that,there was a significant inverse association between mean LAA/AA HU ratios with increasing grades of LAASEC.Grade 0 and Grade 1,Grade 1 and Grade 2 LAASEC were significantly different(P<0.01)between the three indicators,while Grade 2 and Grade 3,Grade 3 and Grade 4,Grade 4 LAASEC and thrombus between the three indicators were not statistically significant.The delayed phase CCT quantitative analysis showed that,there was significant difference in the three indexes between grade 4 LAASEC and thrombus(P<0.01),while there was no significant difference between grade 2 and grade 3,grade3 and grade 4 LAASEC.The ROC curves of LAA/AA,LAA/LA and LAA were plotted with the early phase LAASEC(?grade 1)as the positive event.The area under the curves of LAA/AA,LAA/LA and LAA were 0.902,0.825 and 0.853,respectively.The sensitivity,specificity,PPV,NPV and accuracy of LAAEC(? grade 1)were 88.6%,80.7%,84.2%,and 86.0%and 85.0%respectively,when LAA/AA had the cutoff point of 0.904 according the largest Youden's index.When the cutoff point of LAA/AA was 0.670,the sensitivity,specificity,PPV,NPV and accuracy of LAASEC(? grade 2)were 100.0%,89.3%,74.6%,100.0%and 90.0%.Conclusion:? CCT has good specificity and PPV in diagnosing LAASEC(?gradel)with visual analysis,quantitative analysis makes up for the lack of visual analysis,and improves the sensitivity and NPV of LAASEC(?grade1)combined with LAA/AA at the cutoff point 0.904.? CCT has an excellent diagnostic value in diagnosing LAASEC(?grade2).LAASEC(?grade2)could be ruled out either no filling defect or the LAA/AA>0.670 on the early phase CCT,to avoid unnecessary TEE inspection.?LAA/AA was better than other quantitative indicator like LAA/LA and LAA in evaluating LAASEC.The delayed CCT scan is the key to identify LAASEC and LAA thrombosis. |
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