Biomedical subjects

Sebastian Ley

Publications and source records attributed to Sebastian Ley.

At least 37 records · Page 2Linked to original sources

PubMed2005

Assessment of hemodynamic changes in the systemic and pulmonary arterial circulation in patients with cystic fibrosis using phase-contrast MRI.

Cystic fibrosis (CF) leads to disabling lung disease and pulmonary hypertension (PH). The goal of this study was to assess the hemodynamics in the systemic and pulmonary arterial circulation of patients with CF using MRI. Ten patients with CF and 15 healthy volunteers were examined (1.5-T MRI). Phase-contrast flow measurements were assessed in the ascending aorta, pulmonary trunc, and the left and right pulmonary arteries (PA), resulting in the following parameters: peak velocity (PV) (centimeters per second) velocity rise gradient (VRG), time to PV (milliseconds), and the average area (centimeters squared). The blood flow ratio between the right and left lungs and the bronchosystemic shunt were calculated. For the ascending aorta and pulmonary trunc no parameter was significantly different between both populations. In the right PA a significantly lower PV (p=0.001) and VRG (p=0.02) was found. In the left PA there was a significantly (p=0.007) lower PV but no significant (p=0.07) difference between the VRG. The areas of the right (p=0.08) and left (p=0.5) PA were not significantly enlarged. For the volunteers a linear increase of PV in both PA was found with age, while it decreased in patients with CF. The blood flow distribution (right/left lung) showed no significant (p=0.7) difference between the groups. There was a significantly (p<0.001) higher bronchosystemic shunt volume in patients with CF (1.3 l/min) than in volunteers (0.1 l/min). Magnetic resonance based flow measurements in the right and left PA showed first indications for early development of PH. The significant increase in bronchosystemic shunt volume might be indicative fo the extent of parenchymal changes.

Adult↗

PubMed2005

Comparison of relative forced expiratory volume of one second with dynamic magnetic resonance imaging parameters in healthy subjects and patients with lung cancer.

PURPOSE: To assess relative forced expiratory volume in one second (FEV1/vital capacity (VC)) in healthy subjects and patients with a lung tumor using dynamic magnetic resonance imaging (dMRI) parameters. MATERIALS AND METHODS: In 15 healthy volunteers and 31 patients with a non-small-cell lung carcinoma stage I (NSCLC I), diaphragmatic length change (LE1) and craniocaudal (CC) intrathoracic distance change within one second from maximal inspiration (DE1) were divided by total length change (LE(total), DE(total)) as a surrogate of spirometric FEV1/VC using a true fast imaging with steady-state precession (trueFISP) sequence (TE/TR = 1.7/37.3 msec, temporal resolution = 3 images/second). Influence of tumor localization was examined. RESULTS: In healthy volunteers FEV1/VC showed a highly significant correlation with LE1/LE(total) and DE1/DE(total) (r > 0.9, P < 0.01). In stage IB tumor patients, comparing tumor-bearing with the non-tumor-bearing hemithorax, there was a significant difference in tumors of the middle (LE1/LE(total) = 0.63 +/- 0.05 vs. 0.73 +/- 0.04, DE1/DE(total) = 0.66 +/- 0.05 vs. 0.72 +/- 0.04; P < 0.05) and lower (P < 0.05) lung region. Stage IA tumor patients showed no significant differences with regard to healthy subjects. CONCLUSION: dMRI is a simple noninvasive method to locally determine LE1/LE(total) and DE1/DE(total) as a surrogate of FEV1/VC in volunteers and patients. Tumors of the middle and lower lung regions have a significant influence on these MRI parameters.

Adult↗

PubMed2005

Intraindividual comparison of 1.0 M gadobutrol and 0.5 M gadopentetate dimeglumine for time-resolved contrast-enhanced three-dimensional magnetic resonance angiography of the upper torso.

PURPOSE: To compare the signal characteristics and bolus dynamics of 1.0 M gadobutrol and 0.5 M Gd-DTPA for time-resolved, three-dimensional, contrast-enhanced (CE) MRA of the upper torso. MATERIALS AND METHODS: Ten healthy volunteers were examined with time-resolved three-dimensional CE-MRA (scan time per three-dimensional data set: 0.86 second; voxel size: 3.6 x 2 x 6.3 mm(3)). Each volunteer underwent eight individual examinations after intravenous injection of 0.05 and 0.1 mmol/kg body weight (b.w.) of 1.0 M gadobutrol and 0.5 M Gd-DTPA using two injection rates (2.5 and 5 mL/second). The data analysis included quantitative measurements of the peak signal-to-noise ratio (SNR) and bolus dispersion (full width at half maximum (FWHM)) in the pulmonary artery, left atrium, and thoracic and abdominal aortas. RESULTS: No significant differences in the peak SNR and bolus dispersion were observed between gadobutrol and Gd-DTPA for all dose levels and injection rates in any of the vascular segments. For both contrast agents a dose of 0.1 mmol/kg b.w. injected with 5 mL/second achieved the highest SNR in all vascular segments. CONCLUSION: For the imaging parameters used in this study, higher-concentrated gadolinium chelates offer no relevant advantages for time-resolved three-dimensional CE-MRA of the upper torso.

Body Mass Index↗

PubMed2005

Evaluation of lung volumetry using dynamic three-dimensional magnetic resonance imaging.

RATIONALE AND OBJECTIVES: We sought to investigate lung volume and surface measurements during the breathing cycle using dynamic three-dimensional magnetic resonance imaging (3D MRI). MATERIALS AND METHODS: Breathing cycles of 20 healthy volunteers were examined using a 2D trueFISP sequence (3 images/second) in combination with a model and segmented 3D FLASH sequence (1 image/second) MR images using view sharing. Segmentation was performed semiautomatically using an interactive region growing technique. Vital capacity (VC) was calculated from MRI using the model (2D) and counting the voxels (3D) and was compared with spirometry. RESULTS: VC from spirometry was 4.9+/-0.9 L, 4.4+/-1.2 L from 2D MRI measurement, and 4.7+/-0.9 L for 3D MRI. Using the 3D technique, correlation to spirometry was higher than using the 2D technique (r>0.95 vs. r>0.83). Using the 3D technique, split lung volumes and lung surface could be calculated. There was a significant difference between the left and right lung volume in expiration (P<0.05). CONCLUSIONS: Dynamic 3D MRI is a noninvasive tool to evaluate split lung volumes and lung surfaces during the breathing cycle with a high correlation to spirometry.

Adult↗

PubMed2005

Effect of inspiratory and expiratory breathhold on pulmonary perfusion: assessment by pulmonary perfusion magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The effect of breathholding on pulmonary perfusion remains largely unknown. The aim of this study was to assess the effect of inspiratory and expiratory breathhold on pulmonary perfusion using quantitative pulmonary perfusion magnetic resonance imaging (MRI). METHODS AND RESULTS: Nine healthy volunteers (median age, 28 years; range, 20-45 years) were examined with contrast-enhanced time-resolved 3-dimensional pulmonary perfusion MRI (FLASH 3D, TR/TE: 1.9/0.8 ms; flip angle: 40 degrees; GRAPPA) during end-inspiratory and expiratory breathholds. The perfusion parameters pulmonary blood flow (PBF), pulmonary blood volume (PBV), and mean transit time (MTT) were calculated using the indicator dilution theory. As a reference method, end-inspiratory and expiratory phase-contrast (PC) MRI of the pulmonary arterial blood flow (PABF) was performed. RESULTS: There was a statistically significant increase of the PBF (delta = 182 mL/100 mL/min), PBV (delta = 12 mL/100 mL), and PABF (delta = 0.5 L/min) between inspiratory and expiratory breathhold measurements (P < 0.0001). Also, the MTT was significantly shorter (delta = -0.5 sec) at expiratory breathhold (P = 0.03). Inspiratory PBF and PBV showed a moderate correlation (r = 0.72 and 0.61, P < or = 0.008) with inspiratory PABF. CONCLUSION: Pulmonary perfusion during breathhold depends on the inspiratory level. Higher perfusion is observed at expiratory breathhold.

Adult↗

PubMed2005

Paired inspiratory/expiratory volumetric thin-slice CT scan for emphysema analysis: comparison of different quantitative evaluations and pulmonary function test.

PURPOSES: The aim of the study was to use three-dimensional high-resolution CT scan data sets in inspiration and expiration for the quantitative evaluation of emphysema. Using an advanced dedicated semiautomatic analysis tool, the functional inspiratory/expiratory shifts of emphysema volume and clusters were quantified. The pulmonary function test (PFT) served as the clinical "gold standard." MATERIALS AND METHODS: Thirty-one patients (9 women and 22 men; mean [+/- SD] age, 60 +/- 8 years) who had severe emphysema due to COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] class III and IV) were included in the study. All patients underwent paired inspiratory/expiratory multidetector CT scans (slice thickness, 1/0.8 mm) and pulmonary function tests (PFTs). CT scan data were analyzed with self-written emphysema detection solftware. It provides lung volume (LV), emphysema volume (EV), emphysema index (EI), and four clusters of emphysema with different volumes (from 2, 8, 65, and 120 mm(3)). These results were correlated with total lung capacity (TLC), intrathoracic gas volume (ITGV), and residual volume (RV) derived from PFT results. RESULTS: Inspiratory LV correlated with TLC (r = 0.9), expiratory LV with ITGV (r = 0.87), and RV (r = 0.83). Expiratory EV correlated better with ITGV (r = 0.88) and RV (r = 0.93) than with inspiratory EV (r = 0.83 and 0.88, respectively). The mean inspiratory EI was 54 +/- 13%, and it decreased to 43 +/- 15% in expiration. However, the individuals showed a broad spectrum of changes of EI (mean, 11%; range, 1 to 28%), and no differences in inspiratory/expiratory EI and changes in EI or LV were found between GOLD III and GOLD IV patients. In expiration, there was a change from the large emphysema cluster (-37%) to the intermediate cluster (+15%) and small cluster (+13% and +11%, respectively). The change of volume of the large emphysema cluster after expiration correlated well with the changes in LV (r = 0.9), EV (r = 0.99), EI (r = 0.85), and MLD (r = 0.76). CONCLUSION: Emphysema volumes measured from expiratory MDCT scans better reflect PFT abnormalities in patients with severe emphysema than those from inspiratory scans. Volumetric cluster analysis provided deeper insights into the local hyperinflation and expiratory obstruction of large emphysematous clusters.

Adult↗

PubMed2005

Time-resolved contrast-enhanced three-dimensional magnetic resonance angiography of the chest: combination of parallel imaging with view sharing (TREAT).

RATIONALE AND OBJECTIVES: In view sharing, some parts of k-space are updated more often than others, leading to an effective shortening of the total acquisition time. Undersampling of high-frequency k-space data, however, can result in artifacts at the edges of blood vessels, especially during the rapid signal intensity changes. The objective of this study was to evaluate a new time-resolved echo-shared angiographic technique (TREAT) combining parallel imaging with view sharing. First, the presence of artifacts arising from different temporal interpolation schemes was evaluated in simulations of the point spread function. Second, the image quality and presence of artifacts of time-resolved parallel three-dimensional magnetic resonance angiography (3D MRA) of the chest, acquired with and without view sharing, was assessed in a clinical study of patients with cardiovascular or pulmonary disease. MATERIALS AND METHODS: Using parameters from a time-resolved parallel 3D MRA sequence without view sharing (parallel MRA), giving a 33% increase in spatial resolution, our simulations have revealed that k-space segmentation in 3 regions provides acceptable artifacts. Thirty-six consecutive patients (mean age, 50 +/- 16 years; 15 females, 22 males) were examined in a clinical study with TREAT. The image data were compared with that of a group of 31 consecutive patients (mean age, 46 +/- 19 years; 12 females, 19 males) examined with a conventional time-resolved parallel MRA sequence without view sharing (parallel MRA). The image quality and presence of artifacts was assessed in a blind comparison by 2 radiologists in consensus using MPR and MIP reconstructions. Furthermore, the peak SNR of the pulmonary artery and aorta was compared between both MRA sequences. RESULTS: The image quality of TREAT was rated significantly higher than that of the parallel MRA sequence without view sharing: depending on the orientation of MPR and MIP reconstructions, an excellent image quality was found in 69-89% with TREAT and in 45-71% with the parallel MRA protocol without view sharing, respectively. The presence of artifacts was equal with both sequences. CONCLUSION: View sharing can be successfully combined with other acceleration techniques, such as parallel imaging. TREAT allows the assessment of the thoracic vasculature with a high temporal and spatial resolution.

Cardiovascular Diseases↗

PubMed2004

Respiratory lumenal change of the pharynx and trachea in normal subjects and COPD patients: assessment by cine-MRI.

The purpose of this study was to use cine-MRI during continuous respiration to measure the respiratory lumenal diameter change in the pharynx and at an upper tracheal level. Fifteen non-smokers and 23 chronic obstructive pulmonary disease (COPD) patients with smoking history (median 50 pack-years) were included. Cine-MRI with seven frames/s was performed during continuous respiration. Minimal and maximal cross-sectional lumenal diameters within the pharynx and the upper tracheal lumen area were measured. The median diameter change in the pharynx (tracheal area) was 70% (1.4 cm(2)) in volunteers and 76% (1.7 cm(2)) in smokers (P=0.98, P=0.04). Tracheal lumenal collapse was a median of 43% in volunteers and 64% in smokers (P=0.011). No clear disease-related difference of the pharynx-lumen was found. The maximal cross-sectional area of the upper trachea lumen as well as the respiratory collapse was larger in COPD patients than in normal subjects. This information is important for the modelling of ventilation and prediction of drug deposition, which are influenced by the airway diameter.

Aged↗

PubMed2004

Analysis of intrathoracic tumor mobility during whole breathing cycle by dynamic MRI.

PURPOSE: To assess diaphragm, lung region, and tumor mobility during the whole breathing cycle using dynamic MRI. A generalized safety margin concept for radiotherapy planning was calculated and compared with an individualized concept. METHODS AND MATERIALS: The breathing cycles of 20 patients with solitary lung tumors (15 Stage I non-small-cell lung carcinoma, 5 small solitary metastases) were examined with dynamic MRI (true Fast imaging with steady precision, three images per second). The deep inspiratory and expiratory positions of the diaphragm, upper, middle, and lower lung regions, and the tumor were measured in three dimensions. The mobility of tumor-bearing and corresponding tumor-free regions was compared. Tumor mobility in quiet respiration served as an MRI-based safety margin concept. RESULTS: The motion of the lung regions was significantly greater in the lower regions than in the upper regions (5 +/- 2 cm vs. 0.9 +/- 0.4 cm, p < 0.05). Tumor-bearing lung regions showed a significantly lower mobility than the corresponding noninvolved regions (p < 0.05). In quiet respiration, tumor mobility showed a high variability; a safety margin of 3.4 mm in the upper, 4.5 mm in the middle, and 7.2 mm in the lower region was calculated. CONCLUSION: Dynamic MRI is a simple, noninvasive method to evaluate intrathoracic tumor mobility for therapy planning. Because of the high variability of tumor mobility, an individual safety margin is recommended.

Adult↗

PubMed2004

Chronic thromboembolic pulmonary hypertension: pre- and postoperative assessment with breath-hold MR imaging techniques.

PURPOSE: To evaluate the potential of breath-hold magnetic resonance (MR) imaging techniques in morphologic and functional assessment of patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and after surgery. MATERIALS AND METHODS: Thirty-four patients with CTEPH were examined before and after pulmonary thromboendarterectomy (PTE). For morphologic assessment, contrast material-enhanced MR angiography was used; for assessment of hemodynamics, velocity-encoded gradient-echo sequences and cine gradient-echo sequences along the short axis of the heart were performed. Contrast-enhanced MR angiography was compared with selective digital subtraction angiography (DSA) for depiction of central thromboembolic material and visualization of the pulmonary arterial tree. Functional analysis included calculation of left and right ventricular ejection fractions and peak velocities, net forward volumes per heartbeat, and blood volume per minute in the left and right pulmonary arteries and ascending aorta. Flow measurements were compared with invasively measured mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance (PVR) measurements. Nonparametric Wilcoxon and sign tests were used for statistical analysis. RESULTS: MR angiography revealed typical findings of CTEPH (intraluminal webs and bands, vessel cutoffs, and organized central thromboemboli) in all patients. It depicted pulmonary vessels up to the segmental level in all cases. For subsegmental arteries, DSA revealed significantly more patent vessel segments than did MR angiography (733 versus 681 segments, P <.001). MR angiography revealed technical success of surgery in 33 of 34 patients. Patients had reduced right ventricular ejection fractions and pulmonary peak velocities that significantly increased after PTE (P <.001 for both). Right ventricular ejection fraction had good correlation with PVR (r = 0.6) and MPAP (r = 0.7). The postoperative decrease in MPAP correlated well with the increase in right ventricular ejection fraction (r = 0.8). Postoperatively, there was complete reduction of a preoperatively existing bronchosystemic shunt volume in 33 of 34 patients. CONCLUSION: Breath-hold MR imaging techniques enable morphologic and semiquantitative functional assessment of patients with CTEPH.

Adult↗

PubMed2004

Measurement of diaphragmatic length during the breathing cycle by dynamic MRI: comparison between healthy adults and patients with an intrathoracic tumor.

The purpose of this study was to assess diaphragmatic length and shortening during the breathing cycle in healthy volunteers and patients with a lung tumor using dynamic MRI (dMRI). In 15 healthy volunteers and 28 patients with a solitary lung tumor, diaphragmatic motion and length were measured during the breathing cycle using a trueFISP sequence (three images per second in the coronal and sagittal plane). Time-distance curves and maximal length reduction (= shortening) of the diaphragm were calculated. The influence of tumor localization on diaphragmatic shortening was examined. In healthy volunteers maximal diaphragmatic shortening was 30% in the coronal and 34% in the sagittal orientation, with no difference between both hemithoraces. Tumors of the upper and middle lung region did not affect diaphragmatic shortening. In contrast, tumors of the lower lung region changed shortening significantly ( P<0.05). In hemithoraces with a tumor in the lower region, shortening was 18% in the coronal and 19% in the sagittal plane. The ratio of diaphragmatic length change from inspiration to expiration changed significantly from healthy subjects (inspiration length >> expiratory length, P<0.05) to patients with a tumor in the lower lung region (inspiratory length = expiratory length). dMRI is a simple, non-invasive method to evaluate diaphragmatic motion and shortening in volunteers and patients during the breathing cycle. Tumors of the lower lung region have a significant influence on shortening of the diaphragm.

Adult↗

PubMed2004

3D pulmonary perfusion MRI and MR angiography of pulmonary embolism in pigs after a single injection of a blood pool MR contrast agent.

The purpose of this study was to assess the feasibility of contrast-enhanced 3D perfusion MRI and MR angiography (MRA) of pulmonary embolism (PE) in pigs using a single injection of the blood pool contrast Gadomer. PE was induced in five domestic pigs by injection of autologous blood thrombi. Contrast-enhanced first-pass 3D perfusion MRI (TE/TR/FA: 1.0 ms/2.2 ms/40 degrees; voxel size: 1.3 x 2.5 x 4.0 mm3; TA: 1.8 s per data set) and high-resolution 3D MRA (TE/TR/FA: 1.4 ms/3.4 ms/40 degrees; voxel size: 0.8 x 1.0 x 1.6 mm3) was performed during and after a single injection of 0.1 mmol/kg body weight of Gadomer. Image data were compared to pre-embolism Gd-DTPA-enhanced MRI and post-embolism thin-section multislice CT (n = 2). SNR measurements were performed in the pulmonary arteries and lung. One animal died after induction of PE. In all other animals, perfusion MRI and MRA could be acquired after a single injection of Gadomer. At perfusion MRI, PE could be detected by typical wedge-shaped perfusion defects. While the visualization of central PE at MRA correlated well with the CT, peripheral PE were only visualized by CT. Gadomer achieved a higher peak SNR of the lungs compared to Gd-DTPA (21 +/- 8 vs. 13 +/- 3). Contrast-enhanced 3D perfusion MRI and MRA of PE can be combined using a single injection of the blood pool contrast agent Gadomer.

Animals↗

PubMed2004

Assessment of pulmonary hypertension by CT and MR imaging.

In the recent World Health Organization (WHO) classification the group of pulmonary arterial hypertension (PH) comprises the classic primary pulmonary hypertension and several conditions with definite or very high risk factors to develop pulmonary arterial hypertension. Therapeutic advances drive the need for a comprehensive pre-therapeutic evaluation for optimal treatment. Furthermore, follow-up examinations need to be performed to monitor changes in disease status and response to therapy. Up to now, the diagnostic imaging work-up of PH comprises mainly echocardiography, invasive right heart catheterization and ventilation/perfusion scintigraphy. Due to technical advances helical computed tomography (CT) and magnetic resonance imaging (MRI) became more important in the evaluation and for differential diagnosis of pulmonary arterial hypertension. Both modalities are reviewed and recommendations for clinical use are given.

Heart Diseases↗

PubMed2004

Hybrid segmentation and virtual bronchoscopy based on CT images.

RATIONALE AND OBJECTIVES: Introduction of combination of the segmentation tool SegoMeTex and the virtual endoscopy system VIVENDI to perform virtual endoscopic inspections of the human lung. This virtual bronchoscopy system enables visualization of the tracheobronchial tree down to seventh generation. Furthermore, the modified virtual system visualizes hidden structures such as segmented vascular system or tumors. MATERIALS AND METHODS: The segmentation is based on image data acquired by a multislice computed tomography scanner. SegoMeTex is used to segment the tracheobronchial tree by a hybrid system with minimal user action. Similarly, the complementary pulmonary arterial can be segmented, whereas additional structures such as tumors are marked manually. On this dataset, subsequently, data structures of the inner surface for virtual endoscopy are generated. Finally, the dataset can be explored by a virtual bronchoscopy procedure using the VIVENDI system. RESULTS: The segmentation method was successfully tested on 22 patients. The hybrid segmentation system identified bronchi up to the sixth generation with a sensitivity of more than 58%, and a positive predictive value of more than 90%. After the segmentation, the datasets are explored interactively (>30 fps on a standard personal computer platform in real-time rendering) using the virtual endoscopy software. The exploration exposed a high-quality reconstruction, even of small structures throughout the dataset. CONCLUSION: Virtual bronchoscopy in combining with a highly sensitive segmentation is a valuable tool for the localization and measurement of stenosis for resection planning.

Bronchial Diseases↗

PubMed2004

Measurement of tumor diameter-dependent mobility of lung tumors by dynamic MRI.

BACKGROUND AND PURPOSE: To assess the influence of tumor diameter on tumor mobility and motion of the tumor bearing hemithorax during the whole breathing cycle in patients with stage I non-small-cell lung cancer (NSCLC) using dynamic MRI. PATIENTS AND METHODS: Breathing cycles of thirty-nine patients with solitary NSCLCs were examined using a trueFISP sequence (three images per second). Patients were divided into three groups according to the maximal tumor diameter in the transverse plane (<3, 3-5 and >5 cm). Continuous time-distance curves and deep inspiratory and expiratory positions of the chest wall, the diaphragm and the tumor were measured in three planes. Motion of tumor-bearing and corresponding contralateral non-tumor bearing regions was compared. RESULTS: Patients with a tumor >3 cm showed a significantly lower diaphragmatic motion of the tumor bearing compared with the non-tumor bearing hemithorax in the craniocaudal (CC) directions (tumors 3-5 cm: 23.4+/-1.2 vs 21.1+/-1.5 cm (P<0.05); tumors >5 cm: 23.4+/-1.2 vs 20.1+/-1.6 cm (P<0.01). Tumors >5 cm in the lower lung region showed a significantly lower mobility compared with tumors <3 cm (1.8+/-1.0 vs 3.8+/-0.7 cm, P<0.01) in the CC directions. CONCLUSIONS: Dynamic MRI is a simple non-invasive method to differentiate mobility of tumors with different diameters and its influence on the surrounding tissue. Tumor diameter has a significant influence on tumor mobility and this might be taken into account in future radiotherapy planning.

Adult↗

PubMed2004

Contrast-enhanced three-dimensional pulmonary perfusion magnetic resonance imaging: intraindividual comparison of 1.0 M gadobutrol and 0.5 M Gd-DTPA at three dose levels.

RATIONALE AND OBJECTIVES: To compare 1.0 M gadobutrol and 0.5 M Gd-DTPA for contrast-enhanced three-dimensional pulmonary perfusion magnetic resonance imaging (3D MRI). MATERIALS AND METHODS: Ten healthy volunteers (3 females; 7 males; median age, 27 years; age range, 18-31 years) were examined with contrast-enhanced dynamic 3D MRI with parallel acquisition technique (FLASH 3D; reconstruction algorithm: generalized autocalibrating partially parallel acquisitions; acceleration factor: 2; TE/TR/alpha: 0.8/1.9 milliseconds/40 degrees; FOV: 500 x 375 mm; matrix: 256 x 86; slab thickness: 180 mm; 36 partitions; voxel size: 4.4 x 2 x 5 mm; TA: 1.48 seconds). Twenty-five consecutive data sets were acquired after intravenous injection of 0.025, 0.05, and 0.1 mmol/kg body weight of gadobutrol and Gd-DTPA. Quantitative measurements of peak signal-to-noise ratios (SNR) of both lungs were performed independently by 3 readers. Bolus transit times through the lungs were assessed from signal intensity time curves. RESULTS: The peak SNR in the lungs was comparable between gadobutrol and Gd-DTPA at all dose levels (15.7 vs. 15.5 at 0.1 mmol/kg bw; 12.9 vs. 12.5 at 0.05 mmol/kg bw; 7.6 vs. 8.9 at 0.025 mmol/kg bw). A dose of 0.1 mmol/kg achieved the highest peak SNR compared with all other dose levels (P < 0.05). A higher peak SNR was observed in gravity dependent lung (P < 0.05). Despite different injection volumes, transit times of the contrast bolus did not differ between both agents. CONCLUSION: Higher concentrated gadolinium chelates offer no advantage over standard 0.5 M Gd-DTPA for contrast-enhanced 3D MRI of lung perfusion.

Adolescent↗

PubMed2004

Evaluation of chest motion and volumetry during the breathing cycle by dynamic MRI in healthy subjects: comparison with pulmonary function tests.

RATIONALE AND OBJECTIVES: To investigate diaphragm and chest wall motion during the whole breathing cycle using magnetic resonance imaging (MRI) and a volumetric model in correlation with spirometry. MATERIALS AND METHODS: Breathing cycles of 15 healthy volunteers were examined using a trueFISP sequence (5 slices in 3 planes, 3 images per second). Time-distance curves were calculated and correlated to spirometry. A model for vital capacity (VC), continuous time-dependent vital capacity (tVC), and investigating the influence of horizontal and vertical parameters on tVC was introduced. RESULTS: Time-distance curves of the breathing cycle using MRI correlated highly significant with spirometry (P < 0.0001). VC calculated by the model was similar to VC measured in spirometry (5.00 L vs. 5.15 L). tVC correlated highly significantly with spirometry (P < 0.0001). Vertical parameters had a more profound influence on tVC change than horizontal parameters. CONCLUSIONS: Dynamic MRI is a simple noninvasive method to evaluate local chest wall motion and respiratory mechanics. It widens the repertoire of tools for lung examination with a high temporal resolution.

Adult↗

PubMed2004

Functional evaluation of emphysema using diffusion-weighted 3Helium-magnetic resonance imaging, high-resolution computed tomography, and lung function tests.

PURPOSE: To assess the emphysematous enlargement of distal airspaces and concomitant large and small airway disease using diffusion-weighted 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 Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [EI]), and LFT. RESULTS: Transplanted lungs: mean ADC = 0.17 cm/s, MLD = -848 H, EI = 22%. Emphysematous lungs: mean ADC = 0.33 cm/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 [le] 0.4). CONCLUSION: In this initial study, He-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.

Female↗