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  • 1
    Abstract: OBJECTIVE: To longitudinally evaluate effects of smoking cessation on quantitative CT in a lung cancer screening cohort of heavy smokers over 4 years. METHODS: After 4 years, low-dose chest CT was available for 314 long-term ex-smokers (ES), 404 continuous smokers (CS) and 39 recent quitters (RQ) who quitted smoking within 2 years after baseline CT. CT acquired at baseline and after 3 and 4 years was subjected to well-evaluated densitometry software, computing mean lung density (MLD) and 15th percentile of the lung density histogram (15TH). RESULTS: At baseline, active smokers showed significantly higher MLD and 15TH (-822+/-35 and -936+/-25 HU, respectively) compared to ES (-831+/-31 and -947+/-22 HU, p〈0.01-0.001). After 3 years, CS again had significantly higher MLD and 15TH (-801+/-29 and -896+/-23 HU) than ES (-808+/-27 and -906+/-20 HU, p〈0.01-0.001) but also RQ (-813+/-20 and -909+/-15 HU, p〈0.05-0.001). Quantitative CT parameters did not change significantly after 4 years. Importantly, smoking status independently predicted MLD at baseline and year 3 (p〈0.001) in multivariate analysis. CONCLUSION: On quantitative CT, lung density is higher in active smokers than ex-smokers, and sustainably decreases after smoking cessation, reflecting smoking-induced inflammation. Interpretations of quantitative CT data within clinical trials should consider smoking status. KEY POINTS: * Lung density is higher in active smokers than ex-smokers. * Lung density sustainably decreases after smoking cessation. * Impact of smoking cessation on lung density is independent of potentially confounding factors. * Smoke-induced pulmonary inflammation and particle deposition influence lung density on CT.
    Type of Publication: Journal article published
    PubMed ID: 28884215
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  • 2
    Keywords: THIN-SECTION CT ; INFANTS ; CHILDREN ; asthma ; LUNG-DISEASE ; cystic fibrosis ; SCORING SYSTEMS ; DIMENSIONS ; airway dimensions ; airway disease ; CHEST RADIOGRAPH ; chronic obstructive pulmonary disease ; FLOW LIMITATION ; quantitative computed tomography ; WALL THICKNESS
    Abstract: Purpose: To evaluate the fully automatic quantification of airway dimensions on chest multidetector computed tomography (MDCT) performed in cystic fibrosis (CF) patients. Airflow indices including predicted forced expiratory volume in 1 second (FEV1%) were used to study the impact on regional lung function. Materials and Methods: MDCT data of patients with CF (14 children and 23 adults) and of control patients (11 children and 22 adults) were used to compute total diameter (TD), lumen area (LA), and wall thickness (WT) using dedicated software. Pulmonary function testing including FEV1% was performed in parallel and correlated with MDCT parameters in a generation-based analysis. Results: TD was largely increased in CF patients (third-generation to fourth-generation airways in children, first to ninth in adults; P 〈 0.05). LA remained unchanged, but WT was also larger in CF compared with controls (third generation to sixth generation in children, first to eleventh in adults; P 〈 0.05). In adult CF patients significant negative correlations for TD, LA, and WT with FEV1% were found for intermediate airways (fifth to seventh generation; r = -0.7 to -0.9) but not in pediatric CF patients and controls. Conclusions: Automatic airway analysis succeeded in quantifying specific pathologies such as airway dilatation and wall thickening in CF patients at different ages. Moreover, our results indicate a shift in main airflow resistance to intermediate airways in cases of chronic CF. The objective computational parameters TD, LA, and WT should be considered for assessment and follow-up of CF airway disease
    Type of Publication: Journal article published
    PubMed ID: 23222199
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  • 3
    Keywords: CT ; DIAGNOSIS ; EMPHYSEMA ; MRI ; COMPUTED-TOMOGRAPHY ; MANAGEMENT ; COLLAPSE ; COPD ; TRACHEOBRONCHOMALACIA
    Abstract: BACKGROUND: Advanced-stage chronic obstructive pulmonary disease (COPD) is associated with severely altered respiratory dynamics. Dynamic airway instability is usually diagnosed by invasive bronchoscopy. Cine-computed tomography (CT) may be used alternatively, but is limited to predefined anatomical positions. Also, a paradoxical diaphragmatic motion has been described in patients with emphysema. OBJECTIVES: As the airways and chest wall show inherently high contrast to airway lumen and lung tissue, low-dose CT acquisitions potentially suffice for depicting tracheobronchial and chest wall motion. Therefore, we propose low-dose dynamic respiratory-gated multidetector CT (4D-CT) of the whole chest as a new method to assess respiratory dynamics. METHODS: 4D-CT was performed in 3 patients (52, 62 and 76 years old) with suspected tracheal instability due to COPD or tracheal stenosis at minimal pitch (0.09) and radiation exposure (1.4-1.9 mSv) during regular tidal breathing registered by a belt system. Image reconstruction involved a raw data-based iterative algorithm (1.5-mm slice thickness, 1.0-mm z-axis increment, 5% respiratory increment), resulting in a stack of 6,700 images, which were evaluated with a 4D-viewing tool. Results: An excessive dynamic collapse of the trachea in combination with tracheobronchomalacia (TBM) of the main-stem and segmental bronchi, and a paradoxical diaphragmatic motion were demonstrated in 1 case. Moreover, we detected a saber-sheath trachea and main-stem TBM in another case. The third case showed a fixed tracheal stenosis. CONCLUSIONS: 4D-CT provides unprecedented z-axis coverage and time-resolved volumetric datasets of the whole chest. Airway instability, stenosis and paradoxical diaphragmatic motion may be assessed simultaneously, preceding interventions such as airway stabilization or lung volume reduction.
    Type of Publication: Journal article published
    PubMed ID: 24557362
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  • 4
    Keywords: evaluation ; Germany ; LUNG ; ALGORITHM ; computers,diagnostic aid ; CT ; DENSITY ; DIAGNOSIS ; EMPHYSEMA ; INFORMATION ; QUANTIFICATION ; TOOL ; VOLUME ; PATIENT ; INDEX ; REDUCTION ; REGION ; REGIONS ; PARAMETERS ; MORPHOLOGY ; PARENCHYMA ; AIRWAY ; bronchi,CT ; computed tomography (CT) ; COMPUTED-TOMOGRAPHY IMAGES ; computer programs ; emphysema,pulmonary ; HRCT ; lung,CT ; LUNG-DISEASE ; PULMONARY ; PULMONARY-EMPHYSEMA ; SEGMENT ; SOFTWARE TOOL ; VOLUMES
    Abstract: Purpose: Introduction of a novel software tool (YACTA - yet another CT analyzer) for detection and quantification of pulmonary emphysema in thin-slice chest MDCT data sets. Materials and Methods: Consisting of grey-level threshold-based algorithms (e. g., region-growing), expert rules and morphological image postprocessing YACTA segments the tracheobronchial tree prior to the detection and quantification of pulmonary emphysema. In addition to general parameters, such as the mean lung density (MLD) and the emphysema index (EI - also described as pixel index PI), the previously described bullae index (BI) is transformed into a three-dimensional parameter for a morphological description of emphysema. A first evaluation of chest MDCT data sets of 11 patients was performed as well as a comparison of MLD, lung volume (LV), emphysema volume (EV) and PI calculated with two established commercial tools of Siemens Medical Solutions (Volume(C) and Pulmo(C)). Furthermore, the BI was calculated with YACTA. Results: YACTA processed the image data without manual interaction and demonstrated more user-comfort than (Volume(C) and Pulmo(C)) software, which require manual correction especially for lung segmentation at the hilar regions to separate central airways from lung parenchyma. MLD, LV, and EV values calculated with YACTA were systematically higher (Pulmo(C): + 50 HU/+ 597 ml/+ 159 ml; Volume(C): + 32 HU/+ 110ml/ + 155 ml). Different segmentation algorithms are responsible for this: YACTA includes areas not assessed by mere threshold-based techniques. Constantly lowered LV values of Pulmo(C) are caused by a missing dilatation algorithm. The error correction as a special feature of YACTA results in increased emphysema volumes and indices. The segmentation of the tracheobronchial tree lowers the part of airways falsely classified as emphysema. Conclusion: The new developed software shows higher user comfort as established by semi-automated tools. Results of LV, EV, MLD and PI are comparable or moderately different. Automatic calculation of a BI is possible, providing information about bullous morphology of pulmonary emphysema. Further studies are necessary to correlate data with clinical or pathological parameters
    Type of Publication: Journal article published
    PubMed ID: 15383971
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  • 5
    Keywords: 3D-HRCT, ABNORMALITIES, CANDIDATES, chest, CLUSTER, CLUSTERS, CT, DISEASE, EMPHYSEMA, FUNCTION TESTS
    Abstract: Purpose: To assess the relationship between lung parenchymal destruction and impaired pulmonary perfusion on a lobar level using CT and MRI in patients with emphysema. Material and methods: Forty-five patients with severe emphysema (GOLD III and IV) underwent inspiratory 3D-HRCT and contrast-enhanced MR-perfusion (1.5T; 3.5 mm x 1.9 mm x 4 mm). 3D-HRCT data was analyzed using a software for detection and visualization of emphysema. Emphysema was categorized in four clusters with different volumes and presented as overlay on the CT. CT and lung perfusion were visually analyzed for three lobes on each side using a four-point-score to grade the abnormalities on CT (1: predominantly small emphysema-clusters to 4: 〉75% large emphysema-clusters) and MRI (1: normal perfusion to 4: no perfusion). Results: A total of 270 lobes were evaluated. At CT, the score was 1 for 9 lobes, 2 for 43, 3 for 77, and 4 for 141 lobes. At MRI, the score was 1 for 13 lobes, 2 for 45, 3 for 92, and 4 for 120 lobes. Matching of lung parenchymal destruction and reduced perfusion was found in 213 lobes (weighted kappa = 0.8). The score was higher on CT in 44, and higher on MRI in 13 lobes. Conclusion: 3D-HRCT and 3D MR-perfusion show a high lobar agreement between parenchymal destruction and reduction of perfusion in patients with severe emphysema. (c) 2007 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 17320333
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  • 6
    Keywords: ALGORITHM, ALGORITHMS, CT, DIAGNOSIS, DISEASE, DISEASES, EMPHYSEMA, Germany, LUNG, measurement, QUAN
    Abstract: The new technology of the Multislice-CT provides volume data sets with approximately isotropic resolution, which permits a non invasive measurement of diffuse lung diseases like emphysema in the 3D space. The aim of our project is the development of a full automatic 3D CAD (Computer Aided Diagnosis) software tool for detection, quantification and characterization of emphysema in a thoracic CT data set. It should supply independently an analysis of an image data set to support the physician in clinical daily routine. In this paper we describe the developed 3D algorithms for the segmentation of the tracheo-bronchial tree, the lungs and the emphysema regions. We present different emphysema describing indices
    Type of Publication: Journal article published
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  • 7
    Keywords: Germany ; LUNG ; chest ; CLASSIFICATION ; DENSITY ; DIAGNOSIS ; EMPHYSEMA ; IMAGES ; INFORMATION ; QUANTIFICATION ; segmentation ; SYSTEM ; thorax ; TOOL ; VOLUME ; TIME ; COMPUTED-TOMOGRAPHY ; QUANTITATIVE CT ; QUANTITATIVE-ANALYSIS ; HRCT ; SOFTWARE TOOL ; PROGRAM ; DEPENDENCE ; TRACHEOBRONCHIAL TREE ; TECHNICAL ASPECTS ; LEVEL ; technique ; LUNG-VOLUME ; EXTENT ; TOOLS ; MULTISLICE CT ; PROGRAMS ; AGREEMENT ; ALPHA(1)-ANTITRYPSIN DEFICIENCY ; CT high resolution ; CT quantitative ; DENSITY MASK ; EXCLUSION ; LUNG DENSITOMETRY ; postprocessing ; REPEATABILITY ; tissue characterization ; VOLUME REDUCTION SURGERY
    Abstract: Purpose: The data records of thin-section MSCT of the lung with approx. 300 images are difficult to use in manual evaluation. A computer-assisted pre-diagnosis can help with reporting. Furthermore, post-processing techniques, for instance, for quantification of emphysema on the basis of three-dimensional anatomical information might be improved and the workflow might be further automated. Materials and Methods: The results of 4 programs (Pulmo (R), Volume (R), YACTA and PulmoFUNC) for the quantitative analysis of emphysema (lung and emphysema volume, mean lung density and emphysema index) of 30 consecutive thin-section MSCT datasets with different emphysema severity levels were compared. The classification result of the YACTA program for different types of emphysema was also analyzed. Results: Pulmo (R) and Volume (R) have a median operating time of 105 and 59 minutes respectively due to the necessity for extensive manual correction of the lung segmentation. The programs PulmoFUNC and YACTA, which are automated to a large extent, have a median runtime of 26 and 16 minutes, respectively. The evaluation with Pulmo (R) and Volume (R) using 2 different datasets resulted in implausible values. PulmoFUNC crashed with 2 other datasets in a reproducible manner. Only with YACTA could all graphic datasets be evaluated. The lung volume, emphysema volume, emphysema index and mean lung density determined by YACTA and PulmoFUNC are significantly larger than the corresponding values of Volume (R) and Pulmo (R) (differences: Volume (R): 119 cm(3)/65 cm(3)/1%/17 HU, Pulmo (R): 60 cm(3)/96 cm(3)/1%/37 HU). Classification of the emphysema type was in agreement with that of the radiologist in 26 panlobular cases, in 22 paraseptalen cases and in 15 centrilobular emphysema cases. Conclusion: The substantial expenditure of time obstructs the employment of quantitative emphysema analysis in the clinical routine. The results of YACTA and PulmoFUNC are affected by the dedicated exclusion of the tracheobronchial system. These fully automatic tools enable not only fast quantification without manual interaction, but also a reproducible measurement without user dependence
    Type of Publication: Journal article published
    PubMed ID: 17021978
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  • 8
    Keywords: radiotherapy ; Germany ; LUNG ; MODEL ; chest ; DENSITY ; segmentation ; VENTILATION ; VOLUME ; DISEASES ; TIME ; PATIENT ; pig ; CYCLE ; ACQUISITION ; PRESSURE ; RECONSTRUCTION ; FEASIBILITY ; DEVICES ; RE ; technique ; CT images ; LUNG-VOLUME ; animal ; SET ; animal model ; respiratory gating ; retrospective ; 4-DIMENSIONAL COMPUTED-TOMOGRAPHY ; 4D-MDCT ; AERATION ; AIRWAYS ; laser sensor ; lung volume ; mean lung density
    Abstract: Respiratory gated 3D-MDCT acquisition of the whole chest over time (4D-MDCT) allow retrospective reconstruction of raw data at any point of the respiratory cycle might be beneficial in severely ill or sedated patients. Aim of this feasibility study was to investigate 2 prototype devices as input for retrospective respiratory gating in order to calculate lung volumes (LVs) and mean lung densities (MLDs) over time. Sixteen-row MDCT data were acquired in 5 ventilated pigs using a laser sensor and charge-coupled devine (CCD) camera and retrospectively reconstructed at every 10% of the respiratory cycle. Semiautomatic segmentation of the 3D data sets was performed, and LV and MLD were calculated. Data acquisition was successful in all cases. The mean difference of LV between maximum inspiration and expiration was 246 and 240 mL (laser and CCD, respectively). The mean difference of MLD between inspiration and expiration was 70 (laser) and 67 (CCD) HU. The lowest MLD was found at the beginning of the respiratory cycle (0%) for laser, and at 90% for CCD. Both gating devices allowed for reliable 4D-MDCT image acquisition. No differences were found for calculated LV and MLD, whereas the respiratory cycle was more precisely detected using the laser based gating device
    Type of Publication: Journal article published
    PubMed ID: 17162648
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  • 9
    Keywords: 4-dimensional, 4-DIMENSIONAL COMPUTED-TOMOGRAPHY, animal, ANIMAL-MODEL, animals, ARTIFICIAL-RESPIRAT
    Abstract: Purpose: This feasibility study in healthy animals should prove the concept that it is possible to quantitatively assess the effects of different ventilatory settings on the lung parenchyma during ongoing ventilation in respiratory gated 4-dimensional (D)-computed tomography (CT). For this purpose, the influence of different tidal volumes and positive end-expiratory pressure (PEEP) on quantitative assessment of lung volumes (LVs) and lung compartments was analyzed. Methods: Five anesthetized and ventilated (20 breaths/min, inspiratory/expiratory ratio of 1:2) healthy pigs underwent 16-row multidetector CT with retrospective respiratory gating using a noncontact charge-coupled device camera as a gating device. The device was connected to the scanner instead of the electrocardiogram gating unit. Parameters for retrospective scans were collimation 1 mm, 120 kV, 300 mA, gantry rotation time 0.5 seconds, helical pitch 2.4. Two tidal volumes (3 00 mL and 450 mL) and 3 PEEP levels (0, 5, and 10 cm H2O) were applied resulting in 6 scans per animal. Images were reconstructed throughout the respiratory cycle in increments of 10%. Semiautomatic segmentation provided LV, mean lung density (MLD), and different lung compartments (atelectasis, hypoventilated, normal ventilated, hyperventilated). Results: At tidal volume 300 mL the inspiratory LV were 1.05, 1.26, and 1.5 L and expiratory LV 0.75, 0.99, and 1.24 L (PEEP 0, 5, 10 cm H2O, respectively). Differences of MLD between inspiration and expiration were 86, 65, and 46 HU. At tidal volume 450 mL, the inspiratory LV were 1.21, 1.43, and 1.72 L, and expiratory LV were 0.78, 1.01, and 1.34 L (for PEEP 0, 5, 10 cm H2O). Differences of MLD between inspiration and expiration were 109, 86, and 59 HU. A clear oscillatory wave of the normal and hypoventilated volumes was found at PEEP 0, with increase in PEEP the hypoventilated areas became increasingly normal ventilated, the amplitude of the curves decreased, and hyperventilated areas increased. Conclusion: Using a new 4D-CT technique we were able to demonstrate the effect of different ventilation settings on the whole lung during the whole respiratory cycle. The disadvantages of static lung imaging or dynamic 2D-CT can be overcome. The possibility of quantitative evaluation of the whole lung and direct visualization and measurement of recruitment during different ventilation settings might be a great benefit for patients suffering from inhomogeneous lung injury and failure
    Type of Publication: Journal article published
    PubMed ID: 18496053
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  • 10
    Keywords: ACCURACY, airway geometry measurement, analysis, BRONCHIECTASIS, closed-form solution for the measur
    Abstract: The technology of multislice X-ray computed tomography (MSCT) provides volume data sets with approximately isotropic resolution, which permits a noninvasive 3-D measurement and quantification of airway geometry. In different diseases, like emphysema, chronic obstructive pulmonary disease (COPD), or cystic fribrosis, changes in lung parenchyma are associated with an increase in airway wall thickness. In this paper, we describe an objective measuring method of the airway geometry in the 3-D space. The limited spatial resolution of clinical CT scanners in comparison to thin structures like airway walls causes difficulties in the measurement of the density and the thickness of these structures. Initially, these difficulties will be addressed and then a new method is introduced to circumvent the problems. Therefore the wall thickness is approximated by an integral based closed-form solution, based on the volume conservation property of convolution. We evaluated the method with a phantom containing 10 silicone tubes and proved the repeatability in datasets of eight pigs scanned twice. Furthermore, a comparison of CT datasets of 16 smokers and 15 nonsmokers was done. Further medical studies are ongoing
    Type of Publication: Journal article published
    PubMed ID: 18270063
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