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  • 1
    Keywords: evaluation ; Germany ; LUNG ; chest ; CT ; FOLLOW-UP ; follow-up studies ; IMAGES ; SUPPORT ; VENTILATION ; VOLUME ; RESOLUTION ; PATIENT ; MRI ; helium ; HEALTHY ; HYPERPOLARIZED HE-3 ; motion correction ; MR imaging ; PULMONARY ; VOLUMES ; RECIPIENTS ; BRONCHIOLITIS ; bronchiolitis obliterans ; lung transplantation ; pulmonary function ; PULMONARY-FUNCTION ; TRANSPLANT RECIPIENTS
    Abstract: The aim of this study was to evaluate the possible contribution of He-3-MRI to detect obliterative bronchiolitis (OB) in the follow-up of lung transplant recipients. Nine single- and double-lung transplanted patients were studied by an initial and a follow-up He-3-MRI study. Images were evaluated subjectively by estimation of ventilation defect area and quantitatively by individually adapted threshold segmentation and subsequent calculation of ventilated lung volume. Bronchiolitis obliterans syndrome (BOS) was diagnosed using pulmonary function tests. At He-3-MRI, OB was suspected if ventilated lung volume had decreased by 10% or more at the follow-up MRI study compared with the initial study. General accordance between pulmonary function testing and He-3-MRI was good, although subjective evaluation of He-3-MRI underestimated improvement in ventilation as obtained by pulmonary function tests. The He-3-MRI indicated OB in 6 cases. According to pulmonary function tests, BOS was diagnosed in 5 cases. All diagnoses of BOS were also detected by He-3-MRI. In 2 of these 5 cases, He-3-MRI indicated OB earlier than pulmonary function tests. The results support the hypothesis that He-3-MRI may be sensitive for early detection of OB and emphasize the need for larger prospective follow-up studies
    Type of Publication: Journal article published
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  • 2
    Keywords: evaluation ; Germany ; IN-VIVO ; LUNG ; CT ; DENSITY ; EMPHYSEMA ; imaging ; VOLUME ; DISEASE ; computed tomography ; PATIENT ; INDEX ; TRANSPLANTATION ; CONTRAST ; FLOW ; MRI ; magnetic resonance imaging ; FORM ; GAS ; tomography ; COMPUTED-TOMOGRAPHY ; HEALTHY ; HYPERPOLARIZED HE-3 ; DIFFUSION ; AIRWAY ; HRCT ; resonance imaging ; HIGH-RESOLUTION ; OBSTRUCTION ; lung transplantation ; FUNCTIONAL-CHARACTERIZATION ; AIRWAYS DISEASE ; apparent diffusion coefficient ; COEFFICIENT ; hyperpolarized (3)Helium ; lung function ; PULMONARY-FUNCTION TESTS
    Abstract: Purpose: To assess the emphysematous enlargement of distal airspaces and concomitant large and small airway disease using diffusion-weighted (3)Helium-magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT), and lung function tests (LFT). Methods: Seven patients were examined after single lung transplantation (LTx) and 1 before double LTx for various forms of emphysema. Five patients after double LTx served as controls. Patients were assessed by (3)Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [EI]), and LFT. Results: Transplanted lungs: mean ADC = 0.17 cm(2)/s, MLD -848 H, EI 22%. Emphysematous lungs: mean ADC = 0.33 cm(2)/s, MLD -922 H; EI = 54%. Good correlations were found between ADC and MLD (r = 0.6), EI (r = 0.8), intrathoracic gas volume (r = 0.7), forced expiratory volume in 1 second (r = 0.7), and forced expiratory flows (r = 0.7). In contrast, HRCT only provided moderate correlations with LFT (EI: r = 0.5; MLD: r [1e] 0.4). Conclusion: In this initial study, He-3-MRI yield good correlations with HRCT and agrees better than HRCT with the functional characterization of emphysema regarding hyperinflation, large and small airway disease as provided by LFT
    Type of Publication: Journal article published
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  • 3
    Keywords: BLOOD ; Germany ; LUNG ; MODEL ; chest ; CT ; IMAGES ; SUPPORT ; VENTILATION ; computed tomography ; BLOOD-FLOW ; pig ; FLOW ; NO ; CARE ; DIFFERENCE ; PARAMETERS ; tomography ; RECRUITMENT ; PRESSURE ; CEREBRAL-BLOOD-FLOW ; COMPUTED-TOMOGRAPHY ; SERIES ; INCREASE ; LIFE ; DYNAMIC CT ; methods ; PORCINE MODEL ; CIRCULATION ; MEDICINE ; dynamic ; DERECRUITMENT ; ARDS ; ASSISTED VENTILATION ; Basic life support (BLS) ; BYSTANDER CARDIOPULMONARY-RESUSCITATION ; CARDIAC-ARREST ; Cardiopulmonary resuscitation (CPR) ; Chest compression ; CPR ; Haemodynamics ; LUNG COLLAPSE ; Return of spontaneous circulation ; TO-MOUTH VENTILATION
    Abstract: Aim: The importance of ventilatory support during cardiac arrest and basic life support is controversial. This experimental study used dynamic computed tomography (CT) to assess the effects of chest compressions only during cardiopulmonary resuscitation (CCO-CPR) on alveolar recruitment and haemodynamic parameters in porcine model of ventricular fibrillation. Materials and methods: Twelve anaesthetized pigs (26 +/- 1 kg) were randomly assigned to one of the following groups: (1) intermittent positive pressure ventilation (IPPV) both during basic life support and advanced cardiac life support, or (2) CCO during basic life support and IPPV during advanced cardiac life support. Measurements were acquired at baseline prior to cardiac arrest, during basic life support, during advanced life support, and after return of spontaneous circulation (ROSC), as follows: dynamic CT series, arterial and central venous pressures, blood gases, and regional organ blood flow. The ventilated and atelectatic lung area was quantified from dynamic CT images. Differences between groups were analyzed using the Kruskal-Wallis test, and a p 〈 0.05 was considered statistically significant. Results: IPPV was associated with cyclic alveolar recruitment and de-recruitment. Compared with controls, the CCO-CPR group had a significantly larger mean fractional area of atelectasis (p = 0.009), and significantly tower PaO2 (p = 0.002) and mean arterial pressure (p = 0.023). The increase in mean atelectatic lung area observed during basic life support in the CCO-CPR groupremained clinically relevant throughout the subsequent advanced cardiac life support period and following ROSC, and was associated with prolonged impaired haemodynamics. No inter-group differences in myocardial and cerebral blood flow were observed. Conclusion: A lack of ventilation during basic life support is associated with excessive atelectasis, arterial hypoxaemia and compromised CPR haemodynamics. Moreover, these detrimental effects remain evident even after restoration of IPPV. (C) 2008 Elsevier Ireland Ltd. ALL rights reserved
    Type of Publication: Journal article published
    PubMed ID: 18556110
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  • 4
    Keywords: BLOOD ; Germany ; LUNG ; MODEL ; CT ; VENTILATION ; computed tomography ; PIGS ; RESOLUTION ; PATIENT ; INJURIES ; pig ; INDUCTION ; DYNAMICS ; CYCLE ; ACQUISITION ; GAS ; DAMAGE ; tomography ; RECRUITMENT ; PRESSURE ; PARENCHYMA ; COMPUTED-TOMOGRAPHY ; HEALTHY ; COLLAPSE ; complications,acute respiratory distress syndrome ; INJURY ; lung,lavage ; lung,respirator therapy ; measurement techniques,dynamic computed tomography ; OXYGENATION ; RESPIRATORY-DISTRESS-SYNDROME ; SHUNT
    Abstract: Background. Fast dynamic computed tomography (dCT) has been used to assess regional dynamics of lung inflation and deflation processes. The aim of this study was to relate ventilation-induced changes in lung density distribution, as measured over several respiratory cycles by dCT, to oxygenation and shunt fraction in a lavage acute respiratory distress syndrome model. Methods. Six anaesthetized pigs underwent pressure-constant ventilation (FIO2=1.0, inspiratory:expiratory ratio=1:1) before and after induction of lung damage by saline lavage. Mean airway pressure (P (aw) over bar) was varied (8, 13, 18, 23, 28, 33, and 38 cm H2O) in random order. At each P (aw) over bar level, dCT acquisitions were performed over several respiratory cycles (Somatom Plus4, Siemens; supradiaphragmatic transverse slice; thickness=1 mm; temporal resolution=100 ms). During scanning at each P (aw) over bar, arterial and mixed venous blood were obtained for blood gas analysis and shunt calculation. In each CT image, fractional areas (FA) of defined density ranges representing ventilated lung and atelectasis were determined by planimetry using dedicated software. The FA data of individual 100 ms scans were averaged over several respiratory cycles, and expressed as mean FA in percentage of total lung area at each Pawmacr. For atelectatic lung parenchyma a quantitative relationship of the respective mean FA to shunt fraction was studied using regression analysis. Results. Under steady-state conditions, mean FA of atelectasis correlated linearly with the calculated shunt fraction (healthy lungs, r=+0.76; lavaged lungs, r=+0.89). There is a non-linear relationship between mean FA of ventilated lung parenchyma and mean FA of atelectasis with Pa-O 2. Conclusions. We conclude that dCT allows assessment of the effects of ventilator adjustments and resultant Pawmacr; changes upon lung aeration and oxygenation rapidly, and with good spatial and temporal resolution. This may benefit patients with acute lung injury, whose ventilatory pattern may be optimized as early as during their first diagnostic workup
    Type of Publication: Journal article published
    PubMed ID: 14570794
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  • 5
    Keywords: Germany ; LUNG ; CT ; DIAGNOSIS ; QUANTIFICATION ; SPIRAL CT ; TOOL ; VENTILATION ; VISUALIZATION ; VOLUME ; TIME ; STRATEGIES ; COMPUTED-TOMOGRAPHY ; SERIES ; COLLAPSE ; ACUTE LUNG INJURY ; ALVEOLAR RECRUITMENT ; chest CT,dynamic computed tomography,density,volumetry,pig ; CINE CT ; DISTRESS-SYNDROME ; GENERAL-ANESTHESIA ; TRACHEAL INSTABILITY
    Abstract: Purpose: Dynamic CT (dCT) allows visualization and quantification of ventilated lung and atelectases with high temporal resolution during continuous ventilation. This study compares a quantitative image analysis in a subcarinal single slice dCT series versus a whole lung spiral-CT, in order to analyze, whether the distribution of atelectasis of a single dCT series is representative for the whole lung. Materials and Methods: dCT in sliding windows technique (slice thickness 1 mm, temporal increment 100 ms) was performed in 8 healthy pigs 3 cm caudal to the carina during continuous mechanical ventilation. Subsequently, a spiral-CT of the whole lung (slice thickness 2 mm; pitch 1.5; increment 2 mm) was acquired during inspiratory breath hold (airway pressure 20 mbar). Lung segmentation and planimetry of predefined density ranges were achieved using a dedicated software tool in both data-sets. Thus, the fractions of the following functional lung compartments were averaged over time: hyperinflated lung (-1024 to -910 HE), normal ventilated lung -900 to -300 HE) and atelectasis (-300 to +200 HE). Results: Quantitative analysis of dCF-series during continuous respiration correlated with the density analysis in spiral-CT as follows: hyperinflated lung r = 0.56; normal ventilated lung r = 0.83 and atelectases r = 0.84. Analysis of spiral-CT showed the following distribution of functional lung compartments: hyperinflated lung 3.1% normal ventilated lung 77.9% and atelectasis 19.0%. In dCT, hyperinflated lung represented 6.4%, normal ventilated lung 65.2% and atelectasis 28.4% of total the lung area. Conclusion: The results of our study demonstrate that dCT allows monitoring of atelectasis formation in response to different ventilatory strategies. However, a deviation between dCT and spiral-CT has to be taken into account. In subcarinal dCT series, hyperinflated lung areas and atelectases were overestimated due to a craniocaudal gradient of atelectases, whereas normal ventilated lung was underestimated
    Type of Publication: Journal article published
    PubMed ID: 15026956
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  • 6
    Keywords: Germany ; LUNG ; chest ; CT ; EMPHYSEMA ; FOLLOW-UP ; HIGH-RESOLUTION CT ; IMAGES ; TOOL ; VENTILATION ; VOLUME ; PATIENT ; IMPACT ; TRANSPLANTATION ; AIR ; MRI ; SEQUENCE ; DIFFERENCE ; DECREASE ; AGE ; GAS ; EXCHANGE ; PARAMETERS ; QUANTITATIVE CT ; REJECTION ; HYPERPOLARIZED HE-3 ; ORIENTATION ; hyperpolarized ; HRCT ; PULMONARY ; VOLUMES ; fibrosis ; PATTERN ; INHALATION ; CAPACITY ; HIGH-RESOLUTION ; RECIPIENTS ; pulmonary function ; PULMONARY-FUNCTION ; TRANSPLANT RECIPIENTS ; He-3 ; HE-3 GAS ; LUNG-VOLUMES ; COMPUTED DENSITY ; MORPHOMETRY ; single-lung transplantation ; SPIROMETRY ; split-lung function
    Abstract: Objective: To develop and evaluate a postprocessing tool to quantify ventilated split-lung volumes on the basis of He-3-MRI and to apply it in patients after single-lung transplantation (SLTX). High-resolution CT (HRCT) was employed as a reference modality providing split air-filled lung volumes. Lung volumes derived from pulmonary function test results served as clinical parameters and were used as the "gold standard." Material and methods: Eight patients (mean age, 54 years) with emphysema and six patients (mean age, 58 years) with idiopathic pulmonary fibrosis. All patients were evaluated following SLTX. HRCT was performed during inspiration (slice thickness, I mm; increment, 10 mm). For correlation with He-3-MRI, HRCT images were reconstructed In coronal orientation to match the same anatomic levels. Aerated lung was determined by threshold-based segmentation of CT. He-3-MRI was performed on a 1.5-T scanner using a two-dimensional, fast low-angle shot sequence in coronal orientation covering the whole lung after inhalation of a 300-mL bolus of hyperpolarized He-3 gas followed by normal room air for the rest of the tidal volume. Lung segmentation on He-3-MRI was done using different thresholds; Results: In emphysematous patients, He-3-MRI showed excellent correlation (r = 0.9),with vital capacity, while CT correlated (r = 0.8) with total lung capacity. He-3-MRI correlated well with CT (r 〉 0.8) for grafts and native fibrotic lungs. In emphysematous lungs, MRI showed a good correlation (r = 0.7) with the nonemphysematous lung volume from CT. Increasing thresholds in He-3-MRI reveal differences between aerated and ventilated lung areas with a different distribution in emphysema and fibrosis. Conclusions: He-3-MRI is superior to CT in emphysema to demonstrate ventilated lung areas that participate in gas exchange. In fibrosis, He-3-MRI and CT have a similar impact. The decrease pattern and the intraindividual ratio between ventilation of native and transplanted lungs will have to be investigated as a new surrogate for the ventilatory follow-up in patients undergoing SLTX
    Type of Publication: Journal article published
    PubMed ID: 14718438
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  • 7
    Keywords: evaluation ; Germany ; LUNG ; EMPHYSEMA ; imaging ; VENTILATION ; RESOLUTION ; TIME ; PATIENT ; GRAFT ; MRI ; SEQUENCE ; SIGNAL ; PATTERNS ; GAS ; REGION ; REGIONS ; PARENCHYMA ; KINETICS ; MOTION ; REJECTION ; functional MRI ; GRAFT-REJECTION ; HEALTHY ; HYPERPOLARIZED HE-3 ; lung transplant ; motion correction ; NATIVE LUNG ; noble gas MRI ; PULMONARY VENTILATION
    Abstract: Rationale and objectives. The ability of motion corrected dynamic 3 He-magnetic resonance imaging (MRI) to discriminate distributional patterns of inhaled hyperpolarized He-3 between different groups of lung transplant recipients was evaluated. Methods: An ultrafast low-angle shot 2D sequence (temporal resolution 128 ms) was used for ventilation He-3-MRI of 11 single and 6 double lung transplant recipients. After digital motion correction, signal kinetics were evaluated in a tracheal and 7 pulmonary regions of interest. Results from grafts and native lungs as well as from normal and rejected grafts were compared with each other and to reference values from healthy subjects. Results: In emphysema patients, median alveolar rise time, a parameter for increase of alveolar signal, was 0.28 seconds for the graft and 0.48 seconds for the native lung, in fibrosis patients its median was 0.46 seconds for the graft and 0.21 seconds for the native lung. In double lung recipients, alveolar rise time was 0.29 seconds in normal and clinically rejected grafts. Conclusions: Dynamic ventilation He-3-MRI discriminated normal lung grafts from diseased native lungs in single lung recipients. Graft rejection in double lung recipients could not be discriminated
    Type of Publication: Journal article published
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  • 8
    Keywords: SIMULATIONS ; Germany ; IN-VIVO ; LUNG ; MODEL ; ALGORITHM ; CT ; DENSITY ; imaging ; VENTILATION ; computed tomography ; TIME ; SIMULATION ; ACQUISITION ; GAS ; tomography ; COMPUTED-TOMOGRAPHY ; HEALTHY ; nuclear medicine ; PULMONARY ; TEMPORAL VARIATION ; AIRWAY PRESSURE ; LAVAGE ARDS ; INFLATION ; INTEGRAL-EQUATIONS ; MECHANICS ; NMR RELAXATION DATA
    Abstract: In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs
    Type of Publication: Journal article published
    PubMed ID: 15815088
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  • 9
    Keywords: Germany ; LUNG ; imaging ; QUANTIFICATION ; VENTILATION ; validation ; MRI ; GAS ; HYPERPOLARIZED HE-3 ; PULMONARY VENTILATION ; nuclear medicine ; OXYGEN ; SOFTWARE ; HEALTHY-VOLUNTEERS ; TRANSPLANT RECIPIENTS ; COEFFICIENT ; OXYGEN-SENSITIVE HE-3-MRI ; He-3 magnetic resonance imaging ; He-3-MRI ; HR-CT ; RESOLUTION COMPUTED-TOMOGRAPHY ; SENSITIVE HE-3-MRI
    Abstract: The aim of this study was to validate oxygen-sensitive He-3-MRI in noninvasive determination of the regional, two- and three-dimensional distribution of oxygen partial pressure. In a gas-filled elastic silicon ventilation bag used as a lung phantom, oxygen sensitive two- and three-dimensional He-3-MRI measurements were performed at different oxygen concentrations which had been equilibrated in a range of normal and pathologic values. The oxygen partial pressure distribution was determined from He-3-MRI using newly developed software allowing for mapping of oxygen partial pressure. The reference bulk oxygen partial pressure inside the phantom was measured by conventional respiratory gas analysis. In two-dimensional measurements, image-based and gas-analysis results correlated with r = 0.98; in three-dimensional measurements the between-methods correlation coefficient was r = 0.89. The signal-to-noise ratio of three-dimensional measurements was about half of that of two-dimensional measurements and became critical ( below 3) in some data sets. Oxygen-sensitive He-3-MRI allows for noninvasive determination of the two- and three-dimensional distribution of oxygen partial pressure in gas-filled airspaces
    Type of Publication: Journal article published
    PubMed ID: 15856240
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  • 10
    Keywords: Germany ; LUNG ; chest ; EMPHYSEMA ; FOLLOW-UP ; HIGH-RESOLUTION CT ; QUANTIFICATION ; SYSTEM ; VENTILATION ; DISEASE ; PATIENT ; TRANSPLANTATION ; MRI ; COMPUTED-TOMOGRAPHY ; HYPERPOLARIZED HE-3 ; ORIENTATION ; HRCT ; SINGLE ; RECIPIENTS ; PULMONARY-FUNCTION TESTS ; He-3-MRI ; volumetry ; SMALL AIRWAYS ; visual assessment
    Abstract: Purpose: Visual assessment of the ventilation using HRCT and He-3-MRI in patients after single lung transplantation (SLTX). Analysis of specific ventilation defects found with He-3-MRI and morphological changes found with HRCT. Materials and Methods: We evaluated 8male patients (54 +/- 6 years) suffering from emphysema and six patients (3males and 3 females, 58 +/- 9.5 years) suffering from idiopathic pulmonary fibrosis (IPF) after SLTX. The morphological changes at HRCT were classified and localized. In He-3-MRI (2D FLASH), 10 to 14 slices (slice thickness 10 mm, gap 5 mm) were acquired in coronal orientation to cover the whole lung. Ventilation defects were localized and characterized. The visually estimated ventilation was recorded on a 5-point scoring system. A double threshold technique was applied to volumetric quantification in He-3-MRI to serve as internal reference. Results: We found no correlation between morphological changes in HRCT and ventilation defects in He-3-MRI. The visual assessment of ventilation in He-3-MRI was sufficient in patients with emphysema, but this was not confirmed in patients with IPF. The visual assessment in HRCT did not correlate with the volumetric evaluation in both conditions. Conclusion: The various ventilation defects were not linked to specific morphological changes. For the visually assessed ventilation in patients with emphysema, 3He-MRI is superior to HRCT
    Type of Publication: Journal article published
    PubMed ID: 15838756
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