Pulmonary signal-intensity is reproducible and related to tissue density. In COPD subjects with and without bronchiectasis, signal-intensity was also related to pulmonary function and CT measurements.

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In all ex-smokers, ADC values were significantly elevated in regions of PRM gas trapping, and VDP was quantitatively and spatially related to both PRM gas trapping and PRM emphysema. In patients with mild to moderate COPD, VDP was related to PRM gas trapping, whereas in patients with severe COPD, VDP correlated with both PRM gas trapping and PRM emphysema.

In asthma patients, magnetic resonance imaging (MRI) and the lung clearance index (LCI) have revealed persistent ventilation heterogeneity, although its relationship to asthma control is not well understood. Therefore, our goal was to explore the relationship of MRI ventilation defects and the LCI with asthma control and quality of life in patients with severe, poorly controlled asthma.18 patients with severe, poorly controlled asthma (mean±sd 46±12 years, six males/12 females) provided written informed consent to an ethics board approved protocol, and underwent spirometry, LCI and (3)He MRI during a single 2-h visit. Asthma control and quality of life were evaluated using the Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ). Ventilation heterogeneity was quantified using the LCI and (3)He MRI ventilation defect percent (VDP).All participants reported poorly controlled disease (mean±sd ACQ score=2.3±0.9) and highly heterogeneous ventilation (mean±sd VDP=12±11% and LCI=10.5±3.0). While VDP and LCI were strongly correlated (r=0.86, p<0.0001), in a multivariate model that included forced expiratory volume in 1 s, VDP and LCI, VDP was the only independent predictor of asthma control (R(2)=0.38, p=0.01). There was also a significantly worse VDP, but not LCI in asthma patients with an ACQ score >2 (p=0.04) and AQLQ score <5 (p=0.04), and a trend towards worse VDP (p=0.053), but not LCI in asthma patients reporting ≥1 exacerbation in the past 6 months.In patients with poorly controlled, severe asthma MRI ventilation, but not LCI was significantly worse in those with worse ACQ and AQLQ.

Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using a variety of methods, including multiple-breath gas washout and pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural and functional abnormalities in the lungs, and their relationships with important clinical outcomes. We measured ventilation heterogeneity and respiratory impedance in 100 subjects [50 patients with asthma, 22 ex-smokers, and 28 patients with chronic obstructive pulmonary disease (COPD)] using oscillometry and hyperpolarized 3He magnetic resonance imaging (MRI) and determined their relationships with quality of life scores and disease control/exacerbations. We also coregistered MRI ventilation maps to a computational airway tree model to generate patient-specific respiratory impedance predictions for comparison with experimental measurements. In COPD and asthma patients, respectively, forced oscillation technique (FOT)-derived peripheral resistance (5–19 Hz) and MRI ventilation defect percentage (VDP) were significantly related to quality of life (FOT: COPD ρ = 0.4, P = 0.004; asthma ρ = −0.3, P = 0.04; VDP: COPD ρ = 0.6, P = 0.003; asthma ρ = −0.3, P = 0.04). Patients with poorly controlled asthma (Asthmatic Control Questionnaire >2) had significantly increased resistance (5 Hz: P = 0.01; 5–19 Hz: P = 0.006) and reactance (5 Hz: P = 0.03). FOT-derived peripheral resistance (5–19 Hz) was significantly related to VDP in patients with asthma and COPD patients (asthma: ρ = 0.5, P < 0.001; COPD: ρ = 0.5, P = 0.01), whereas total respiratory impedance was related to VDP only in patients with asthma (resistance 5 Hz: ρ = 0.3, P = 0.02; reactance 5 Hz: ρ = −0.5, P < 0.001). Model-predicted and FOT-measured reactance (5 Hz) were correlated in patients with asthma (ρ = 0.5, P = 0.001), whereas in COPD patients, model-predicted and FOT-measured resistance (5–19 Hz) were correlated (ρ = 0.5, P = 0.004). In summary, in patients with asthma and COPD patients, we observed significant, independent relationships for FOT-measured impedance and MRI ventilation heterogeneity measurements with one another and with quality of life scores. NEW & NOTEWORTHY In 100 patients, including patients with asthma and ex-smokers, 3He MRI ventilation heterogeneity and respiratory system impedance were correlated and both were independently related to quality of life scores and asthma control. These findings demonstrated the critical relationships between respiratory system impedance and ventilation heterogeneity and their role in determining quality of life and disease control. These observations underscore the dominant role that abnormalities in the lung periphery play in ventilation heterogeneity that results in patients’ symptoms.

Evidence-based guidance for the use of airway clearance techniques (ACT) in chronic obstructive pulmonary disease (COPD) is lacking in-part because well-established measurements of pulmonary function such as the forced expiratory volume in 1s (FEV1) are relatively insensitive to ACT. The objective of this crossover study was to evaluate daily use of an oscillatory positive expiratory pressure (oPEP) device for 21-28 days in COPD patients who were self-identified as sputum-producers or non-sputum-producers. COPD volunteers provided written informed consent to daily oPEP use in a randomized crossover fashion. Participants completed baseline, crossover and study-end pulmonary function tests, St. George's Respiratory Questionnaire (SGRQ), Patient Evaluation Questionnaire (PEQ), Six-Minute Walk Test and (3)He magnetic resonance imaging (MRI) for the measurement of ventilation abnormalities using the ventilation defect percent (VDP). Fourteen COPD patients, self-identified as sputum-producers and 13 COPD-non-sputum-producers completed the study. Post-oPEP, the PEQ-ease-bringing-up-sputum was improved for sputum-producers (p = 0.005) and non-sputum-producers (p = 0.04), the magnitude of which was greater for sputum-producers (p = 0.03). There were significant post-oPEP improvements for sputum-producers only for FVC (p = 0.01), 6MWD (p = 0.04), SGRQ total score (p = 0.01) as well as PEQ-patient-global-assessment (p = 0.02). Clinically relevant post-oPEP improvements for PEQ-ease-bringing-up-sputum/PEQ-patient-global-assessment/SGRQ/VDP were observed in 8/7/9/6 of 14 sputum-producers and 2/0/3/3 of 13 non-sputum-producers. The post-oPEP change in (3)He MRI VDP was related to the change in PEQ-ease-bringing-up-sputum (r = 0.65, p = 0.0004) and FEV1 (r = -0.50, p = 0.009). In COPD patients with chronic sputum production, PEQ and SGRQ scores, FVC and 6MWD improved post-oPEP. FEV1 and PEQ-ease-bringing-up-sputum improvements were related to improved ventilation providing mechanistic evidence to support oPEP use in COPD. Clinical Trials # NCT02282189 and NCT02282202.

Purpose To measure regional specific ventilation with free-breathing hydrogen 1 (H) magnetic resonance (MR) imaging without exogenous contrast material and to investigate correlations with hyperpolarized helium 3 (He) MR imaging and pulmonary function test measurements in healthy volunteers and patients with asthma. Materials and Methods Subjects underwent free-breathing H and static breath-hold hyperpolarizedHe MR imaging as well as spirometry and plethysmography; participants were consecutively recruited between January and June 2017. Free-breathing H MR imaging was performed with an optimized balanced steady-state free-precession sequence; images were retrospectively grouped into tidal inspiration or tidal expiration volumes with exponentially weighted phase interpolation. MR imaging volumes were coregistered by using optical flow deformable registration to generateH MR imaging-derived specific ventilation maps. Hyperpolarized He MR imaging- andH MR imaging-derived specific ventilation maps were coregistered to quantify regional specific ventilation within hyperpolarized He MR imaging ventilation masks. Differences between groups were determined with the Mann-Whitney test and relationships were determined with Spearman (ρ) correlation coefficients. Statistical analyses were performed with software. Results Thirty subjects (median age: 50 years; interquartile range [IQR]: 30 years), including 23 with asthma and seven healthy volunteers, were evaluated. BothH MR imaging-derived specific ventilation and hyperpolarized He MR imaging-derived ventilation percentage were significantly greater in healthy volunteers than in patients with asthma (specific ventilation: 0.14 [IQR: 0.05] vs 0.08 [IQR: 0.06], respectively, P< .0001; ventilation percentage: 99% [IQR: 1%] vs 94% [IQR: 5%], P < .0001). For all subjects, H MR imaging-derived specific ventilation correlated with plethysmography-derived specific ventilation (ρ = 0.54, P = .002) and hyperpolarizedHe MR imaging-derived ventilation percentage (ρ = 0.67, P < .0001) as well as with forced expiratory volume in 1 second (FEV) (ρ = 0.65, P = .0001), ratio of FEV to forced vital capacity (ρ = 0.75, P < .0001), ratio of residual volume to total lung capacity (ρ = -0.68, P< .0001), and airway resistance (ρ = -0.51, P = .004). H MR imaging-derived specific ventilation was significantly greater in the gravitational-dependent versus nondependent lung in healthy subjects (P = .02) but not in patients with asthma (P = .1). In patients with asthma, coregisteredH MR imaging specific ventilation and hyperpolarized He MR imaging maps showed that specific ventilation was diminished in correspondingHe MR imaging ventilation defects (0.05 ± 0.04) compared with well-ventilated regions (0.09 ± 0.05) (P < .0001). Conclusion H MR imaging-derived specific ventilation correlated with plethysmography-derived specific ventilation and ventilation defects seen by using hyperpolarizedHe MR imaging. RSNA, 2018 Online supplemental material is available for this article.

Cardiac magnetic resonance imaging (MRI) provides a wealth of imaging biomarkers for cardiovascular disease care and segmentation of cardiac structures is required as a first step in enumerating these biomarkers. Deep convolutional neural networks (CNNs) have demonstrated remarkable success in image segmentation but typically require large training datasets and provide suboptimal results that require further improvements. Here, we developed a way to enhance cardiac MRI multi-class segmentation by combining the strengths of CNN and interpretable machine learning algorithms. We developed a continuous kernel cut segmentation algorithm by integrating normalized cuts and continuous regularization in a unified framework. The high-order formulation was solved through upper bound relaxation and a continuous max-flow algorithm in an iterative manner using CNN predictions as inputs. We applied our approach to two representative cardiac MRI datasets across a wide range of cardiovascular pathologies. We comprehensively evaluated the performance of our approach for two CNNs trained with various small numbers of training cases, tested on the same and different datasets. Experimental results showed that our approach improved baseline CNN segmentation by a large margin, reduced CNN segmentation variability substantially, and achieved excellent segmentation accuracy with minimal extra computational cost. These results suggest that our approach provides a way to enhance the applicability of CNN by enabling the use of smaller training datasets and improving the segmentation accuracy and reproducibility for cardiac MRI segmentation in research and clinical patient care.