| Objective When the three common types of lung diseases,lung cancer,tuberculosis and pneumonia,are all manifested as signs of consolidation in the CT image,the diagnosis and differential diagnosis have a certain difficulty,and when these three diseases are only manifested as solitary pulmonary consolidation lesions(SPLs),the qualitative difficulty is more improved.Because of its fast scanning speed and high image resolution,MSCT can provide essential imaging diagnostic basis for early diagnosis and differential diagnosis of these three types of diseases.Previous studies often made the diagnosis and differential diagnosis of these three diseases through the imaging features of the lesions themselves,such as pleural indentation,lobulated sign,speculated sign,vessel convergence and different features of lesion enhancement.In the age of plain film,the appearance of air bronchogram sign was an important basis for the differentiation of pulmonary solid lesions and pleural lesions.With the deepening study of the air bronchogram sign,it was gradually applied to the field of identification in various types of lung solid lesions.Previous studies only focus on the morphological features of bronchial and the relationship between bronchial and intrapulmonary diseases,and simple classification with different types was made.This study aims to analyze the CT features of the air bronchogram sign and to investigate its role in the differentiation of lung cancer,tuberculosis,and pneumonia.The shape and lumen of the bronchi with air bronchogram sign,the length of the involved bronchus with air bronchogram sign,the length of lesion on the same plane and direction,and the ratio between the length of the involved bronchus and that of the lesion were evaluated.Material and Methods1 Inclusion criteria This is a retrospective study.Patients with SPLs from April 2016 to December 2016 were enrolled in this study.They all underwent CT scan.All patients were diagnosed by a review of pathologic reports and clinical records,surgery,bronchoscopy brushings,biopsy,pleural effusion test,and sputum culture.Patients with pathologically confirmed lung cancer,tuberculosis,or pneumonia patients;Patients with a single solid lesion for the CT features of air bronchogram sign.A total of 105 patients were enrolled.2 Exclusion criteria Patients with multiple solid lesions on CT,or no the air bronchogram sign can be found in the SPLs,or no clear clinical diagnosis,or clinical diagnosis of combine lung cancer,pulmonary tuberculosis,pneumonia.3 CT protocols All studies were performed using a 64-row multi-slice CT scanner system(FHILIPS,ingenuity core 128).All images were stored in digital formats.Before the examination,instruct the patient to breathe in and hold breath.CT parameters were as follow:tube voltage of 120 kV,tube current of 224 Ma,rotation time of 0.42 seconds,layer thickness of 5 mm,Then the chest scan was performed according to the preset range and the preset conditions.The lung window and mediastinal window images were reconstructed.4 Imaging analysis After the scanning is completed,the image information is digitally processed by computer.Reconstruction thickness of 1 mm,and reconstruction interval of 1 mm.CT imagines were assessed by 2 radiologists(HQ and JY)blinded to the study design using appropriate window setting to display the morphology of the air bronchogram sign and the maximum length of the bronchus in the lesion more better.For statistical and contrast purposes,the bronchial branches were divided into six lobes:right upper lobe,right middle lobe,right lower lobe,left upper lobe,left lingual lobe and left lower lobe.The right upper lobe was further divided into apical,posterior and anterior segments,and the left upper lobe into apical,posterior and anterior segments.The right middle lobe was further divided into medial segment and lateral segment,the left lung tongue lobe is divided into upper lingual segment and lower lingual segment,the lower lobe of both lungs are divided into dorsal segment,medial,anterior,lateral and posterior basal segments.The anatomic location and number of bronchus involved in the lesions were evaluated successively,and compared with the normal contralateral bronchus of the same level.The evaluated air bronchogram sign included the shape and lumen of the bronchi with air bronchogram sign,the length of the involved bronchus with air bronchogram sign,the length of lesion on the same plane and direction,and the ratio between the length of the involved bronchus and that of the lesion.The shape of bronchi was evaluated by comparing to that of the normal bronchus in the contralateral lung at the same level.The ones with similar shape were defined as normal,those with straight and stiff shape were defined as stiff,and those with twisted shape were defined as tortuous.The patterns of normal,stiff,and tortuous were scored consecutively(normal:0 point,stiff:1 point,and tortuous 2 points).The diameter of the bronchus lumen was compared to that of the normal bronchus in the contralateral lung at the same level.The ones with similar lumen diameter were defined as normal,those with expanded lumen diameter were defined as expansion,those with narrowed lumen diameter were defined as stenosis,and those with both narrowed and expanded lumen diameter were defined as stenosis and expansion coexistence.The lumen patterns were scored as follows:normal(0 point),stenosis(1 point),expansion(2 points),and stenosis and expansion coexistence(3 points).At the reconstructed plane,which showed the longest diameter of the affected bronchus,the linear distance between the proximal end of the bronchus and the end point of the bronchus was measured as the length of the involved bronchus with air bronchogram sign.The length of lesion was also measured on the same plane and direction5 Statistical analysis SPSS(version 17,IBM)software was used for statistical analysis.Chi-squared test was used to analyze the differences in unordered categorical variables.Analysis of variance was performed to analyze differences in continuous categorical variables of different groups.LSD was used for comparison between 2 groups when there was significant difference among 3 groups.P value<.05 was considered statistically significant.ResultsA total of 105 patients were included.There were 39 cases of lung cancer,43 cases of tuberculosis and 23 cases of pneumonia.A total of 172 bronchial segments or subsegments were observed in solid lesions,of which 62 were lung cancer,77 were tuberculosis and 33 were pneumonia.1 The age and gender of patientsThe average age of lung cancer patients was 61.2 + 8.0 years(age range:42-73 years).The mean age of tuberculosis patients was 29.0 + 14.4 years old(age range:6-76 years).The average age of patients with pneumonia was 37.1 + 16.3 years(age range:13-67 years).The age difference between different groups was statistically significant(P<0.05),the lung cancer patients were significantly older.There were 67 males and 38 females,and the proportion of male to female was 26:13;25:18;16:7in the three groups of lung cancer,tuberculosis and pneumonia respectively.There was no significant difference in gender distribution between the three groups(P=0.5867).2 Imaging features of the air bronchogram sign2.1 The shape of the bronchi:Statistical analysis showed that the shape of the bronchi in the lesion was different among patients with lung cancer,tuberculosis,and pneumonia(P=0.0038).The lung cancer group was mostly manifested as stiff(69.35%),followed by those who manifested as normal(24.19%),tortuous(6.45%).In the tuberculosis group,the mostly manifested as stiff too,(44.16%),followed by those who manifested as tortuous(29.87%)and normal(25.97%).In the pneumonia group,mostly manifested as normal(57.58%),followed by stiff(42.42%),and there was no bronchial manifested as tortuous2.2 The lumen of the bronchiStatistical analysis showed that the lumen of the bronchi in the lesion was significantly different among patients with lung cancer,tuberculosis,and pneumonia(P<0.0001).The majority of patients with bronchial stenosis in the lung cancer group(87.10%),and the proportion of patients with normal or stenosis or stenosis coexisting with expansion was less(4.84%,4.84%,3.23%).The majority of patients with tuberculosis were expansion(55.84%),and the proportion of the remaining stenosis,normal lumen,and stenosis coexisted with expansion decreased successively(20.78%,14.29%,9.09%).Among the patients with pneumonia,the most common ones were normal lumen(48.48%),while the other ones with stenosis,expansion,and stenosis coexisted with expansion were quite rare(24.24%,24.24%,3.03%).2.3 The maximum length of the involved bronchus with air bronchogram signThe maximum length of the involved bronchus with air bronchogram sign reconstructed was measured,and the average length of bronchus involved in the lung cancer group was 24.7± 19.9mm(range:3.1-124.1mm).The average length of bronchus involved in tuberculosis group was 31.9 ±7.2mm(range:8.3-93.0mm).The average length of the affected bronchus in the pneumonia group was 28.6± 10.7mm(range:11.1-55mm).The length difference of the air bronchogram between the three groups was not statistically significant(P=0.0526).However,P value was close to 0.05,and comparative analysis showed that there was significant difference between lung cancer group and tuberculosis group(P<0.05),while comparative analysis between other groups showed no significant difference.2.4 The maximum length of lesionsThe maximum length of the lesions was measured in the same direction at the same reconstruction level,and the average length of the lesions in the lung cancer group was 45.7 ± 19.9mm(range:22-124.1mm).The average length of bronchus involved in tuberculosis group was 47.9 ± 45.7mm(range:11.6-93.0mm).The average length of affected bronchus in the pneumonia group was 37.9 ± 13.9mm(range:11.2-78.2mm).There was no statistically significant difference in the maximum length of lesions between the three groups(P=0.3639).2.5 The ratio between the length of the involved bronchus and that of the lesionThe ratio between the length of the involved bronchus and that of the lesion was calculated with lung cancer,tuberculosis and pneumonia group,which is 0.55±0.30;0.76±0.26;0.81 ±0.21.The difference between the three groups was statistically significant(P<0.0001).After comparative analysis by LSD,the difference between the lung cancer group and the tuberculosis group was statistically significant(P<0.05),and the difference between the lung cancer group and the pneumonia group was statistically significant(P<0.05),but the difference between the tuberculosis group and the pneumonia group was not statistically significant(P>0.05).3.1n order to better distinguish the pneumonia group and the tuberculosis group,the AUC was 0.7965 after all the above factors were included in the model,and the discrimination effect was better.Conclusion Make full use of multi-slice CT post-processing technique,through The shape and lumen of the bronchi with air bronchogram sign,The length of the involved bronchus with air bronchogram sign and the ratio between the length of the involved bronchus and that of the lesion can be used to identify of different solitary pulmonary consolidation lesions. |
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