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  • 1
    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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  • 2
    Keywords: CANCER ; COMPUTED-TOMOGRAPHY ; HELICAL CT ; MANAGEMENT ; GUIDELINES ; IMAGE QUALITY ; CHEST CT ; STATEMENT ; SCREENING TRIAL ; LOW-DOSE CT
    Abstract: OBJECTIVES: To evaluate the influence of exposure parameters and raw-data based iterative reconstruction (IR) on the measurement variability of computer-aided nodule volumetry on chest multidetector computed tomography (MDCT). MATERIALS AND METHODS: N=7 porcine lung explants were inflated in a dedicated ex vivo phantom and prepared with n=162 artificial nodules. MDCT was performed eight consecutive times (combinations of 120 and 80 kV with 120, 60, 30 and 12 mAs), and reconstructed with filtered back projection (FBP) and IR. Nodule volume and diameter were measured semi-automatically with dedicated software. The absolute percentage measurement error (APE) was computed in relation to the 120 kV 120 mAs acquisition. Noise was recorded for each nodule in every dataset. RESULTS: Mean nodule volume and diameter were 0.32 +/- 0.15 ml and 12.0 +/- 2.6mm, respectively. Although IR reduced noise by 24.9% on average compared to FBP (p〈0.007), APE with IR was equal to or slightly higher than with FBP. Mean APE for volume increased significantly below a volume computed tomography dose index (CTDI) of 1.0 mGy: for 120 kV 12 mAs APE was 3.8 +/- 6.2% (FBP) vs. 4.0 +/- 5.2% (IR) (p〈0.007); for 80 kV 12 mAs APE was 8.0 +/- 13.0% vs. 9.3 +/- 15.8% (n.s.), respectively. Correlating APE with image noise revealed that at identical noise APE was higher with IR than with FBP (p〈0.05). CONCLUSIONS: Computer-aided volumetry is robust in a wide range of exposure settings, and reproducibility is reduced at a CTDI below 1.0 mGy only, but the error rate remains clinically irrelevant. Noise reduction by IR is not detrimental for measurement error in the setting of semi-automatic nodule volumetry on chest MDCT.
    Type of Publication: Journal article published
    PubMed ID: 23727376
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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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  • 6
    Keywords: DIAGNOSIS ; SYSTEMS ; TIME ; REPRODUCIBILITY ; COMPUTED-TOMOGRAPHY ; THIN-SECTION CT ; magnetic resonance imaging (MRI) ; CHILDREN ; ADULTS ; cystic fibrosis ; Lung disease ; Scoring system
    Abstract: Magnetic resonance imaging (MRI) gains increasing importance in the assessment of cystic fibrosis (CF) lung disease. The aim of this study was to develop a morpho-functional MR-scoring-system and to evaluate its intra- and inter-observer reproducibility and clinical practicability to monitor CF lung disease over a broad severity range from infancy to adulthood. 35 CF patients with broad age range (mean 15.3years; range 0.5-42) were examined by morphological and functional MRI. Lobe based analysis was performed for parameters bronchiectasis/bronchial-wall-thickening, mucus plugging, abscesses/sacculations, consolidations, special findings and perfusion defects. The maximum global score was 72. Two experienced radiologists scored the images at two time points (interval 10weeks). Upper and lower limits of agreement, concordance correlation coefficients (CCC), total deviation index and coverage probability were calculated for global, morphology, function, component and lobar scores. Global scores ranged from 6 to 47. Intra- and inter-reader agreement for global scores were good (CCC: 0.98 (R1), 0.94 (R2), 0.97 (R1/R2)) and were comparable between high and low scores. Our results indicate that the proposed morpho-functional MR-scoring-system is reproducible and applicable for semi-quantitative evaluation of a large spectrum of CF lung disease severity. This scoring-system can be applied for the routine assessment of CF lung disease and maybe as endpoint for clinical trials.
    Type of Publication: Journal article published
    PubMed ID: 21429685
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  • 7
    Keywords: COMPUTED-TOMOGRAPHY ; CONTRAST-ENHANCED MRI ; PULMONARY BLOOD-FLOW ; CYSTIC-FIBROSIS ; hyperpolarized He-3 MRI ; inversion-recovery ; Fourier decomposition ; PARTIAL LIQUID VENTILATION ; COPD PATIENTS ; RABBIT MODEL
    Abstract: Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. Noncontrast-enhanced perfusion imaging is still experimental, either based on arterial spin labeling or Fourier decomposition. The latter is used to separate high- and low-frequency oscillations of lung signal related to the effects of pulsatile blood flow. Lung ventilation: Using contrast-enhanced first-pass perfusion, lung ventilation deficits are indirectly identified by hypoxic vasoconstriction. More direct but still experimental approaches use either inhalation of pure oxygen, an aerosolized contrast agent, or hyperpolarized noble gases. Fourier decomposition MRI based on the low-frequency lung signal oscillation allows for visualization of ventilation without any contrast agent. Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring.
    Type of Publication: Journal article published
    PubMed ID: 24481761
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  • 8
    Abstract: OBJECTIVES: Quantitative multidetector computed tomography (MDCT) as a potential biomarker is increasingly used for severity assessment of emphysema in chronic obstructive pulmonary disease (COPD). Aim of this study was to evaluate the user-independent measurement variability between five different fully-automatic densitometry software tools. MATERIAL AND METHODS: MDCT and full-body plethysmography incl. forced expiratory volume in 1s and total lung capacity were available for 49 patients with advanced COPD (age = 64+/-9 years, forced expiratory volume in 1s = 31+/-6% predicted). Measurement variation regarding lung volume, emphysema volume, emphysema index, and mean lung density was evaluated for two scientific and three commercially available lung densitometry software tools designed to analyze MDCT from different scanner types. RESULTS: One scientific tool and one commercial tool failed to process most or all datasets, respectively, and were excluded. One scientific and another commercial tool analyzed 49, the remaining commercial tool 30 datasets. Lung volume, emphysema volume, emphysema index and mean lung density were significantly different amongst these three tools (p〈0.001). Limits of agreement for lung volume were [-0.195, -0.052l], [-0.305, -0.131l], and [-0.123, -0.052l] with correlation coefficients of r = 1.00 each. Limits of agreement for emphysema index were [-6.2, 2.9%], [-27.0, 16.9%], and [-25.5, 18.8%], with r = 0.79 to 0.98. Correlation of lung volume with total lung capacity was good to excellent (r = 0.77 to 0.91, p〈0.001), but segmented lung volume (6.7+/-1.3 - 6.8+/-1.3l) were significantly lower than total lung capacity (7.7+/-1.7l, p〈0.001). CONCLUSIONS: Technical incompatibilities hindered evaluation of two of five tools. The remaining three showed significant measurement variation for emphysema, hampering quantitative MDCT as a biomarker in COPD. Follow-up studies should currently use identical software, and standardization efforts should encompass software as well.
    Type of Publication: Journal article published
    PubMed ID: 25386874
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  • 9
    Abstract: OBJECTIVES: To evaluate the influence of exposure parameters and raw-data-based iterative reconstruction (IR) on computer-aided segmentation and quantitative analysis of the tracheobronchial tree on multidetector computed tomography (MDCT). MATERIAL AND METHODS: 10 porcine heart-lung-explants were mounted inside a dedicated chest phantom. MDCT was performed at 120kV and 80kV with 120, 60, 30 and 12 mAs each. All scans were reconstructed with filtered back projection (FBP) or IR, resulting in a total of 160 datasets. The maximum number of detected airway segments, most peripheral airway generation detected, generation-specific airway wall thickness (WT), total diameter (TD) and normalized wall thickness (pi10) were compared. RESULTS: The number of detected airway segments decreased slightly with dose (324.8+/-118 at 120kV/120mAs vs. 288.9+/-130 at 80kV/30mAs with FBP, p〈0.05) and was not changed by IR. The 20th generation was constantly detected as most peripheral. WT did not change significantly with exposure parameters and reconstruction algorithm across all generations: range 1st generation 2.4-2.7mm, 5th 1.0-1.1mm, and 10th 0.7mm with FBP; 1st 2.3-2.4mm, 5th 1.0-1.1mm, and 10th 0.7-0.8mm with IR. pi10 was not affected as well (range 0.32-0.34mm). CONCLUSIONS: Exposure parameters and IR had no relevant influence on measured airway parameters even for WT 〈1mm. Thus, no systematic errors would be expected using automatic airway analysis with low-dose MDCT and IR.
    Type of Publication: Journal article published
    PubMed ID: 28767732
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  • 10
    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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