Search

For sensitive diagnosis and monitoring of pulmonary disease, ionizing radiation-free imaging methods are of great importance. A noncontrast and free-breathing proton magnetic resonance imaging (MRI) technique for assessment of pulmonary perfusion is phase-resolved functional lung (PREFUL) MRI. Since there is no validation of PREFUL MRI across different centers and scanners, the purpose of this study was to compare perfusion-weighted PREFUL MRI with the well-established dynamic contrast-enhanced (DCE) MRI across two centers on scanners from two different vendors. Sixteen patients with cystic fibrosis (CF) (Center 1: 10 patients; Center 2: 6 patients) underwent PREFUL and DCE MRI at 1.5T in the same imaging session. Normalized perfusion-weighted values and perfusion defect percentage (QDP) values were calculated for the whole lung and three central slices (dorsal, central, ventral of the carina). Obtained parameters were compared using Pearson correlation, Spearman correlation, Bland–Altman analysis, Wilcoxon signed-rank test, and Wilcoxon rank-sum test. Moderate-to-strong correlations between normalized perfusion-weighted PREFUL and DCE values were found (posterior slice: r = 0.69, p 0.07). The feasibility of PREFUL MRI across two different centers and two different vendors was shown in patients with CF and obtained results were in agreement with DCE MRI.

Purpose: To examine the time-dependent diffusion of fluorinated (19F) gas in human lungs for determination of surface-to-volume ratio in comparison to results from hyperpolarized 129Xe and lung function testing in healthy volunteers and patients with chronic obstructive pulmonary disease. Methods: Diffusion of fluorinated gas in the short-time regime was measured using multiple gradient-echo sequences with a single pair of trapezoidal gradient pulses. Pulmonary surface-to-volume ratio was calculated using a first-order approximation of the time-dependent diffusion in a study with 20 healthy volunteers and 22 patients with chronic obstructive pulmonary disease. The repeatability after 7 days as well as the correlation with hyperpolarized 129Xe diffusion MRI and lung function testing was analyzed. Results: Using 19F diffusion MRI, the median surface-to-volume ratio is significantly decreased in chronic obstructive pulmonary disease patients (S/V = 126 cm-1 [87-144 cm-1]) compared with healthy volunteers (S/V = 164 cm-1 [160–84 cm-1], p < 0.0001). No significant difference was found between measurements within 7 days for healthy (p = 0.88, median coefficient of variation = 4.3%) and diseased subjects (p = 0.58, median coefficient of variation= 6.7%). Linear correlations were found with S/V from 129Xe diffusion MRI (r = 0.85, p = 0.001) and the forced expiratory volume in 1 second (r = 0.68, p < 0.0001). Conclusion: Examination of lung microstructure using time-dependent diffusion measurement of inhaled 19F is feasible, repeatable, and correlates with established measurements.

Background. Regional flow volume loop ventilation-weighted noncontrast-enhanced proton lung MRI in free breathing has emerged as a novel technique for assessment of regional lung ventilation, but has yet not been validated with 129Xenon MRI (129Xe-MRI), a direct visualization of ventilation in healthy volunteers, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD) patients. Purpose. To compare regional ventilation and regional flow volume loops measured by noncontrast-enhanced ventilation-weighted phase-resolved functional lung MRI (PREFUL-MRI) with 129Xe-MRI ventilation imaging and with lung function test parameters. Study Type. Retrospective study. Population. Twenty patients with COPD, eight patients with CF, and six healthy volunteers. Field Strength/Sequence. PREFUL and 129Xe-MRI gradient echo sequences were acquired at 1.5T. Assessment. Coronal slices of PREFUL-MRI (free breathing) and 129Xe-MRI (single breath-hold) were acquired on the same day, matched by their ventrodorsal position and coregistered for evaluation. Ventilation defect percentage (VDP) was calculated based on regional ventilation (RV), regional flow volume loops (RFVL), or 129Xe-MRI with two different threshold methods. A combined VDP was calculated for RV and RFVL. Additionally, lung function testing was performed (such as the forced expiratory volume in 1 second [FEV1]) was used. Statistical Tests. The obtained parameters were compared using Wilcoxon tests, correlated using Spearman's correlation coefficient (r), and agreement between PREFUL and 129Xe-MRI parameters was assessed using Bland-Altman analysis and Dice coefficients. Results. VDP measured by PREFUL and 129Xe were significantly correlated with both thresholding techniques (r = 0.62-0.69, P

INTRODUCTION: The coexistence of COPD and bronchiectasis seems to be common and associated with a worse prognosis than for either disease individually. However, no definition of this association exists to guide researchers and clinicians. METHODS: We conducted a Delphi survey involving expert pulmonologists and radiologists from Europe, Turkey and Israel in order to define the "COPD- [bronchiectasis] BE association".A panel of 16 experts from EMBARC selected 35 statements for the survey after reviewing scientific literature. Invited participants, selected on the basis of expertise, geographical and sex distribution, were asked to express agreement on the statements. Consensus was defined as a score of =6 points (scale 0 to 9) in =70% of answers across two scoring rounds. RESULTS: 102 (72.3%) out of 141 invited experts participated in the first round. Their response rate in the second round was 81%. The final consensus definition of "COPD-BE association" was: "The coexistence of (1) specific radiological findings (abnormal bronchial dilatation, airways visible within 1 cm of pleura and/or lack of tapering sign in =1 pulmonary segment and in >1 lobe) with (2) an obstructive pattern on spirometry ([forced expiratory volume in 1 s] FEV(1)/[forced vital capacity] FVC

Background: Free‐breathing phase‐resolved functional lung (PREFUL)‐MRI may be useful for treatment monitoring in chronic obstructive pulmonary disease (COPD) patients with dyspnea. PREFUL test-retest reliability is essential for clinical application. Purpose: To measure the repeatability of PREFUL‐MRI ventilation (V) and perfusion (Q) parameters. Study Type: Retrospective and prospective. Population: A total of 28 COPD patients and 57 healthy subjects. Field Strength/Sequence. 1.5T MRI/2D spoiled gradient echo imaging. Assessment: V and Q lung parameter maps based on three coronal slices were obtained at baseline and after 14 days (COPD patients) or after a short pause outside the scanner (healthy subjects). Regional ventilation (RVent) and imaging flow volume loops by cross‐correlation (ccVent) were quantified. Q was normalized to the signal of the main pulmonary artery (QN) and quantified (QQuant). Pulmonary pulse wave transit time (pPTT), voxel‐by‐voxel (regional), and whole lung (global) ventilation defect percentage based on RVent (VDPRVent) and ccVent (VDPccVent), perfusion defect percentage (QDP), and ventilation/perfusion match based on RVent (VQMRVent) and ccVent (VQMccVent) were calculated. Statistical Tests: Regional V and Q were analyzed globally for each subject. Each parameter's median of scans 1 and 2 were assessed by Wilcoxon sign rank test. A parameter's repeatability was analyzed by Bland-Altman analyses, coefficients of variation, intraclass correlation coefficients (ICC), and power calculations. The regional voxel repeatability was examined by calculating the Sørensen-Dice coefficient. Results: There was no bias and no significant differences between the first and second MRI for any parameters (P > 0.05). Coefficient of variation ranged from 2.26% (ccVent) to 19.31% (QDP), ICC from 0.93 (QDP) to 0.60 (pPTT), the smallest detectable difference was 0.002 ccVent. Regional comparison showed the highest overlap (84%) in VDPRVent in healthy voxels and the lowest (53%) in VDPccVent defect voxels. Data Conclusion: V and Q PREFUL‐MRI parameters were repeatable over two scan sessions in both healthy controls and COPD patients.

Purpose: To investigate the diffusion of hyperpolarized 129Xe in air spaces at short-time scales for determination of lung surface-to-gas-volume ratio in comparison to results from chemical shift saturation recovery, CT, and established clinical measures. Methods: A pulse sequence for measurement of time‐dependent diffusion of 129Xe in air spaces at short diffusion times was developed. Gas uptake into lung tissue was measured in the same breathhold using chemical shift saturation recovery spectroscopy in the short‐time regime. The potential to obtain the surface‐to‐gas‐volume ratio using a first‐order and second‐order approximation of the short‐time expansion of time‐dependent diffusion according to Mitra et al11 and its diagnostic relevance were tested in a study with 9 chronic obstructive pulmonary diseases patients. Results: Surface‐to‐gas‐volume ratios obtained from time‐dependent diffusion were correlated with results from chemical shift saturation recovery, r = 0.840, P = .005 (first‐order fits), and r = 0.923, P < .001 (second‐order fits), and from CT results for second‐order fits, r = 0.729, P = .026. Group means ± SD were 75.0 ± 15.5 cm−1 (first‐order fits) and 122.3 ± 32.8 cm−1 (second‐order fits) for time‐dependent diffusion, 125.9 ± 43.3 cm−1 for chemical shift saturation recovery, and 159.5 ± 50.9 cm−1 for CT. Surface‐to‐gas‐volume ratios from time‐dependent diffusion with first‐order fits correlated significantly with carbon monoxide diffusing capacity as percent of prediction, r = 0.724, P = .028. Conclusion: Time‐dependent diffusion measurements of 129Xe at short‐time scales down to ~1 ms are feasible in chronic obstructive pulmonary patients and provide clinically relevant information on lung microstructure.

Background: Development of antiinflammatory drugs for lung diseases demands novel methods for noninvasive assessment of inflammatory processes in the lung. Purpose: To investigate the feasibility of hyperpolarized 129Xe MRI, 1H T1 time mapping, and dynamic contrast-enhanced (DCE) perfusion MRI for monitoring the response of human lungs to low-dose inhaled lipopolysaccharide (LPS) challenge compared to inflammatory cell counts from induced-sputum analysis. Study Type: Prospective feasibility study. Population: Ten healthy volunteers underwent MRI before and 6 hours after inhaled LPS challenge with subsequent induced-sputum collection. Field Strength/Sequences: 1.5T/hyperpolarized 129Xe MRI: Interleaved multiecho imaging of dissolved and gas phase, ventilation imaging, dissolved-phase spectroscopy, and chemical shift saturation recovery spectroscopy. 1H MRI: Inversion recovery fast low-angle shot imaging for T1 mapping, time-resolved angiography with stochastic trajectori es for DCE MRI. Assessment: Dissolved-phase ratios of 129Xe in red blood cells (RBC), tissue/plasma (TP) and gas phase (GP), ventilation defect percentage, septal wall thickness, surface-to-volume ratio, capillary transit time, lineshape parameters in dissolved-phase spectroscopy, 1H T1 time, blood volume, flow, and mean transit time were determined and compared to cell counts. Statistical Tests: Wilcoxon signed-rank test, Pearson correlation.

Purpose: To develop a novel technique for voxel‐based mapping of lung microstructural parameters using hyperpolarized 129Xe dissolved‐phase MR imaging during saturation recovery. Methods: A pulse sequence using a highly undersampled stack‐of‐stars trajectory was developed, and low‐rank plus sparse matrix decomposition was employed for reconstruction of regional 129Xe uptake dynamics into lung tissue. In 4 healthy volunteers and 9 patients with chronic obstructive pulmonary disease, the technique was tested and compared to chemical shift saturation recovery spectroscopy in patients. Reproducibility of 129Xe gas uptake imaging was assessed by computing coefficients of variation, and results were compared with other modalities. Results: Numerical simulations and results from in vivo measurements in patients with chronic obstructive pulmonary disease showed that septal wall thickness and surface‐to‐volume ratio can be measured with an accuracy close to spectroscopic measurements. The average of the microstructural parameters of the total lung volume showed good reproducibility (coefficient of variation wall thickness: 7.4% coefficient of variation surface‐to‐volume ratio: 7.5%) and correlated strongly with the findings of global chemical shift saturation recovery spectroscopy. Gravitational gradients of microstructural parameters and increased heterogeneity in chronic obstructive pulmonary disease patients were observed. Conclusion: A novel technique for mapping of regional lung microstructural parameters was introduced, and its feasibility was shown in healthy volunteers and chronic obstructive pulmonary disease patients.

Pulmonary hypertension (PH) is highly heterogeneous and despite treatment advances it remains a life-shortening condition. There have been significant advances in imaging technologies, but despite evidence of their potential clinical utility, practice remains variable, dependent in part on imaging availability and expertise. This statement summarizes current and emerging imaging modalities and their potential role in the diagnosis and assessment of suspected PH. It also includes a review of commonly encountered clinical and radiological scenarios, and imaging and modeling-based biomarkers. An expert panel was formed including clinicians, radiologists, imaging scientists, and computational modelers. Section editors generated a series of summary statements based on a review of the literature and professional experience and, following consensus review, a diagnostic algorithm and 55 statements were agreed. The diagnostic algorithm and summary statements emphasize the key role and added value of imaging in the diagnosis and assessment of PH and highlight areas requiring further research.

Rationale and Objectives: To assess the repeatability of global and regional lung ventilation quantification in both healthy subjects and patients with chronic obstructive pulmonary disease (COPD) using fluorinated (19F) gas washout magnetic resonance (MR) imaging in free breathing. Material and Methods: In this prospective institutional review board-approved study, 12 healthy nonsmokers and eight COPD patients were examined with 19F dynamic gas washout MR imaging in free breathing and with lung function testing. Measurements were repeated within 2 weeks. Lung ventilation was quantified using 19F gas washout time. Repeatability was analyzed for the total lung and on a regional basis using the coefficient of variation (COV) and Bland-Altman plots. Results: In healthy subjects and COPD patients, a good repeatability was found for lung ventilation quantification using dynamic 19F gas washout MR imaging on a global (COV < 8%) and regional (COV < 15%) level. Gas washout time was significantly increased in the COPD group compared to the healthy subjects. Conclusion: 19F gas washout MR imaging provides a good repeatability of lung ventilation quantification and appears to be sensitive to early changes of regional lung function alterations such as normal aging.

Purpose: To evaluate the reproducibility and regional variation of parameters obtained from localized 129Xe chemical shift saturation recovery (CSSR) MR spectroscopy in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD) and to compare the results to 129Xe dissolved‐phase MR imaging. Methods: Thirteen healthy volunteers and 10 COPD patients were scanned twice using 129Xe dissolved‐phase imaging, CSSR, and ventilation imaging sequences. A 16‐channel phased‐array coil in combination with the regularized spectral localization achieved by sensitivity heterogeneity (SPLASH) method was used to perform a regional analysis of CSSR data. Lung function and microstructural parameters were obtained using Patz model functions and their reproducibility was assessed. Results: The Patz model alveolar wall thickness parameter shows good reproducibility on a regional basis with a median coefficient of variation of 6.5% in healthy volunteers and 12.4% in COPD patients. Significant regional differences of lung function parameters derived from localized CSSR were found in healthy volunteers and correlations with spirometric indices were found. Conclusion: Localized 129Xe CSSR provides reproducible estimates of alveolar wall thickness and is able to detect regional differences of lung microstructure.