Diagnostic Value Of Noncontrast Helical Chest CT In Central Acute Pulmonary Embolism

ObjectiveTo evaluate the diagnostic value of high attenuation clot in the pulmonary artery on noncontrast helical chest CT in patients with central acute pulmonary embolism.Materials and methods118 inpatients in our hospital who underwent noncontrast helical chest CT and CT pulmonary angiography(CTPA)were collected from April 2016 to December 2018.Firstly,the noncontrast helical chest CT images were analyzed by two radiologists respectively.The window position was 40 HU and the window width was 160 HU.The abnormal density clot was observed in the pulmonary artery above the pulmonary segment artery.The location and CT value of the abnormal density clot were recorded,and the CT value of the non-abnormal density clot area in the main pulmonary artery was measured as a control.Then the CT pulmonary angiography images were analyzed,and the high density lesions observed on noncontrast helical chest CT images were compared with their CTPA images to determine whether the abnormal density lesions observed on noncontrast CT scan images had corresponding filling defects on CTPA images.To explore the diagnostic value of high density sign on noncontrast helical chest CT for central acute pulmonary embolism.ResultsAmong 118 patients,63 were males and 55 were females,aged from 19 to 84 years,with an average age of(62.5±13.7)years.High density lesions were observed in the pulmonary arteries of 49 patients,including 25 males and 24 females,aged 26-83 years,with an average age of(65.3±13.1)years.There were 177 high density lesions with a minimum CT value of 40 HU,a maximum CT value of(65.7±11.5)HU,and a minimum CT value of 26.3 HU,a maximum CT value of 54.8 HU,an average of(41.2±7)HU in the main pulmonary artery.The difference of CT value between the lesion and the main pulmonary artery was the smallest 5.6 HU,the maximum 61.8 HU,and the average value was(23.8±11.5)HU.Com-paring CT pulmonary angiography images,40 of 49 patients were diagnosed as central a-cute pulmonary embolism.Of the 177 emboli observed on noncontrast helical chest CT,143 had corresponding filling defects on CTPA images.The minimum CT value was 40 HU,the maximum was 89 HU,and the average CT value was(66.7±11.6)HU.The differrence between the mean CT value and the density of the main pulmonary artery was 5.6 HU,the maximum value was 61.8 HU,and the average value was(25.6±11.4)HU.Matched sample t-test was performed for 143 high density lesions and pulmonary artery trunk CT values.The results were t=13.419,p=0.00 < 0.05.The difference was statistically significant.Among 118 patients,40 patients with acute pulmonary embolism had high density lesions on noncontrast helical chest CT images;9patients had no acute pulmonary embolism and high density lesions were observed on noncontrast helical chest CT images;13 patients with acute pulmonary embolism had no high density lesions on noncontrast helical chest CT images;56 patients with-out acute pulmonary embolism had no high density lesions on noncontrast helical chest CT images.The collected data were sorted out and matched by Paired Chi-square test and Kappa test.The results of Paired Chi-square test was p=0.523>0.05 and Kappa test was Kappa=0.621,p<0.05,which showed that the high density sign of noncontrast helical chest CT was in good agreement with CT pulmonary angiography.The sensitivity,specificity,false positive rate(misdiagnosis rate),false negative rate(missed diagnosis rate),positive predictive value and negative predictive value of non-contrast helical chest CT for detection of pulmonary embolism were 75.47%,86.15%,13.8%,24.53%,81.63% and 81.16%,respectively.ConclusionThe high density sign on noncontrast helical chest CT is of great significance in the diagnosis of central acute pulmonary embolism.