Application Of Multi-detector Row Computed Tomography (MDCT) On Bronchus Related To Solitary Pulmonary Lesion

PartⅠCT Imaging Bronchus Related to Solitary Pulmonary Lesion:A Comparison of Minimum Intensity Projection(MinIP) and Multi-Planar Reconstruction(MPR)Objective To investigate the imaging method of multi-detector row computed tomography(MDCT) with minimum intensity projection(MinIP) and multi-planar reconstruction(MPR) for imaging bronchus related to solitary pulmonary lesion (SPL).Methods One hundred subjects(61 men and 39 women;mean age,59 years±13 [standard deviation];age range,25-85 years) with bronchus related to a solitary pulmonary lesion(SPL;mean diameter,26.1 mm±11.2[standard deviation];diameter range,8.1-62.7 mm) included in the study underwent thin-collimation(≤1 mm) chest multi-detector row computed tomography(MDCT).After volume scan raw datasets were acquired,all cross-sectional images were transferred to GE Advantage Workstation 4.3 and reconstructed with no more than 1 mm of slice thickness in 0.3-0.5 mm reconstruction intervals.All reconstructed images were reconstructed retrospectively as MPR and MinIP images with 1 mm,2 mm,3 mm,and 5 mm thickness and 1 mm slice spacing in two orthogonal planes along the long axis of bronchus related to a SPL.The image quality of four kinds of MinIP and MPR image series was evaluated in the aspect of bronchus and pulmonary vascular markings. Generation of the bronchus related to a SPL was evaluated manually by oblique volume rendering technique with very thin cross-sectional images.Statistical evaluation of all data was performed by SPSS 15.0(Chicago,USA) using the Fisher exact test.A p value of less than 0.05 was accepted as indicating a statistically significant difference.Results(1) There is a significant difference between right upper lobe or apical-posterior and anterior segments of left upper lobe(symmetric anatomic part) and the other lung lobes and segments with the oblique coronary plane and oblique sagittal plane combined unit(p＜0.01).(2) The bronchus related to a SPL in sixty of all subjects(60%) belongs to fourth- to sixth-generation bronchi(trachea is generation zero).Overall generation bronchi related to SPL could be seen clearly on 1-2 mm thickness MinIP images and the same thickness MPR images.Only fourth-to fifth-generation bronchi related to SPL was seen clearly in all subjects on 3 mm and 5 mm thickness MinIP images.Not all generation bronchi related to SPL could be seen clearly on 3-mm and 5-mm thickness MPR images.(3) The mean score of display of bronchus decreased with increasing slice thickness.The display of bronchus on 1-3 mm thickness MinIP was superior on 2-mm thickness MPR images(p＜0.05).The interclass correlation coefficient of display of bronchus on 1-mm thickness MinIP and 2-mm thickness MinIP is 0.615 and 0.708,respectively(p＜0.05),but no significant difference on 3-mm and 5-mm thickness MinIP(p＞0.05).The effect of suppression of pulmonary vascular markings was better with increasing slice thickness on MinIP images.There was prominent difference between 2~5 mm thickness MinIP images and 1-mm thickness MPR images(p＜0.01).Conclusion Compared with MPR images,MinIP may display bronchus related to SPL and suppression of pulmonary vascular markings more clearly.PartⅡClinical Application of Minimum Intensity Projection on Solitary Pulmonary Nodule(SPN)Objective To investigate the practical value of multi-detector row computed tomography(MDCT) with minimum intensity projection(MinIP) in solitary pulmonary nodule with bronchus sign.Methods The subjects were 66 patients(56 from part one,33 cases in each sex; mean age,59 years±14[standard deviation];age range,25-85 years old) with bronchus sign related to solitary pulmonary nodule(SPN,mean diameter,21.5 mm±5.2[standard deviation];diameter range,8.1-30.0 mm) included in this study underwent thin-collimation(≤1 mm) chest multi-detector row computed tomography (MDCT).Forty-five cases were malignant SPNs,and twenty-one cases were benign ones.Fifty-six subjects received SPN target scan,and the remained ten thin-section MDCT scan.After volume scan raw datasets were acquired,the ten SPNs were performed thin-section target reconstruction with a slice thickness of no more than 1 mm in 0.3-0.4 mm reconstruction intervals.All subjects` thin-sectional images were transferred to GE ADW 4.3 workstation.2-mm and 5-mm thickness MinIP images and 2-mm thickness MPR images with 1-ram slice spacing were performed in two orthogonal planes along the long axis of bronchus related to SPN.The image quality of display of CT bronchus sign on 2-mm and 5-mm thickness MinIP images was compared with 2-mm thickness MinIP images which the wide window(window wide: 1500 Hu,window level:-500 Hu) was applied.According to the features of shape and the patterns of SPN-bronchus relationship,types of CT bronchus sign were identified. The results were correlated with gross observation and histopathologic specimens. Statistical evaluation of bronchus sign of CT-pathologic correlation was performed by SPSS 15.0(Chicago,USA) using the Fisher exact test.A P value of less than 0.05 was accepted as indicating a statistically significant difference.Results(1) There was a significant difference of mean score of image quality between 2-mm thickness MPR images(3.39)and 2-mm thickness MinIP images(3.89) (p＜0.01).Compared with 2-mm thickness MPR images,the score on 5-mm thickness MinIP images was higher in 39 patients(59.1%),equal in 26 patients(39.4%),and lower in one patient with a nodule in lingula segment.There was a significant difference of mean score of image quality between 2-mm thickness MinIP images and 5-mm thickness MinIP images(3.30)(p＜0.01),but without difference between 2-mm thickness MPR images and 5-mm thickness MinIP images(p＞0.05).The mean score of display CT bronchus sign on 5-mm thickness MinIP images was excellent in 17 subjects(25.8%),good in 26 subjects(39.4%),fair in 20 subjects(30.3%),and very poor in 3 subjects(4.5%).The mean score of display CT bronchus sign on 2-mm thickness MinIP images with wide window was excellent in 39 subjects(59.1%),and good in the remained twenty-seven subjects(40.9%).(2) A classification of CT bronchus sign based on SPN-bronchus relationship with MinIP images,comprising five types:typeⅠ,18(33.3%) malignant SPNs,and 8(38.1%) benign ones,bronchus cut off by the SPN abruptly;typeⅡ,12(24.4%) malignant SPNs,and 4(19%) benign ones,bronchus leading to SPN and tapering in SPN;typeⅢ,22(48.9%) malignant SPNs,and 4(19%) benign ones,bronchus contained within SPN with leafless tree sign,sometimes with irregular narrow,tortuous,or ectatic bronchial lumen;type IV,20(44.4%) malignant SPNs,and 4(19%) benign ones,bronchus adjacent to the edge of SPN with patent lumen;and type v,2(4.4%) malignant SPNs, and 10(47.6%) benign ones,bronchus compressed and narrowed or interrupted by SPN.TypeⅢwas the most common CT bronchus sign in malignant SPNs(p＜0.05). Secondly,typeⅥand typeⅠ(p＞0.05).TypeⅤwas the most common type in benign SPNs,and it's useful in distinguishing benign SPNs from malignant ones (p＜0.01).TypeⅠwas the second common type in benign SPNs.(3) There was no significant difference to show each type of CT bronchus sign between poorly differentiated adenocarcinoma(4 subjects) and moderately differentiated adenocarcinoma(17 subjects,p＞0.05).(4) The number of CT bronchus sign rised with increasing size of SPN.When SPN was less than 1 cm,CT only presents typeⅥ(1 patient) and typeⅤ(1 patient) bronchus sign.When SPN was larger than 1 cm and smaller than 2 cm in size,typeⅠ(9 patients) was the most common bronchus sign, and typeⅢwas rare(3 patients).When SPN was larger than 2 cm and smaller than 3 cm in size,typeⅢwas most common(19 patients),typeⅣ(18 patients) secondly, typeⅤ(7 patients) rarely.Conclusion MinIP with appropriate wide window may reveal an improvement of visualization of CT bronchus sign,and this sign is of great clinical value to help define the nature of a solitary pulmonary nodule.