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Background: Neonatal dynamic tracheal collapse (tracheomalacia, TM) is a common and serious comorbidity in infants, particularly those with chronic lung disease of prematurity (bronchopulmonary dysplasia, BPD) or congenital airway or lung-related conditions such as congenital diaphragmatic hernia (CDH), but the underlying pathology, impact on clinical outcomes, and response to therapy are not well understood. There is a pressing clinical need for an accurate, objective, and safe assessment of neonatal TM., Purpose: To use retrospectively respiratory-gated ultrashort echo-time (UTE) MRI to noninvasively analyze moving tracheal anatomy for regional, quantitative evaluation of dynamic airway collapse in quiet-breathing, nonsedated neonates., Study Type: Prospective., Population/subjects: Twenty-seven neonatal subjects with varying respiratory morbidities (control, BPD, CDH, abnormal polysomnogram)., Field Strength/sequence: High-resolution 3D radial UTE MRI (0.7 mm isotropic) on 1.5T scanner sited in the neonatal intensive care unit., Assessment: Images were retrospectively respiratory-gated using the motion-modulated time-course of the k-space center. Tracheal surfaces were generated from segmentations of end-expiration/inspiration images and analyzed geometrically along the tracheal length to calculate percent-change in luminal cross-sectional area (A % ) and ratio of minor-to-major diameters at end-expiration (r D,exp ). Geometric results were compared to clinically available bronchoscopic findings (n = 14)., Statistical Tests: Two-sample t-test., Results: Maximum A % significantly identified subjects with/without a bronchoscopic TM diagnosis (with: 46.9 ± 10.0%; without: 27.0 ± 5.8%; P < 0.001), as did minimum r D,exp (with: 0.346 ± 0.146; without: 0.671 ± 0.218; P = 0.008). Subjects with severe BPD exhibited a far larger range of minimum r D,exp than subjects with mild/moderate BPD or controls (0.631 ± 0.222, 0.782 ± 0.075, and 0.776 ± 0.030, respectively), while minimum r D,exp was reduced in CDH subjects (0.331 ± 0.171) compared with controls (P < 0.001)., Data Conclusion: Respiratory-gated UTE MRI can quantitatively and safely evaluate neonatal dynamic tracheal collapse, as validated with the clinical standard of bronchoscopy, without requiring invasive procedures, anesthesia, or ionizing radiation., Level of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:659-667., (© 2018 International Society for Magnetic Resonance in Medicine.)

Background: Lung disease is the most frequent cause of morbidity and mortality in patients with cystic fibrosis (CF), and there is a shortage of sensitive biomarkers able to regionally monitor disease progression and to assess early responses to therapy., Purpose: To determine the feasibility of noncontrast-enhanced multivolume MRI, which assesses intensity changes between expiratory and inspiratory breath-hold images, to detect and quantify regional ventilation abnormalities in CF lung disease, with a focus on the structure-function relationship., Study Type: Retrospective., Population: Twenty-nine subjects, including healthy young children (n = 9, 7-37 months), healthy adolescents (n = 4, 14-22 years), young children with CF lung disease (n = 10, 7-47 months), and adolescents with CF lung disease (n = 6, 8-18 years) were studied., Field Strength/sequence: 3D spoiled gradient-recalled sequence at 1.5T., Assessment: Subjects were scanned during breath-hold at functional residual capacity (FRC) and total lung capacity (TLC) through noncontrast-enhanced MRI and CT. Expiratory-inspiratory differences in MR signal-intensity (Δ 1 H-MRI) and CT-density (ΔHU) were computed to estimate regional ventilation. MR and CT images were also evaluated using a CF-specific scoring system., Statistical Tests: Quadratic regression, Spearman's correlation, one-way analysis of variance (ANOVA)., Results: Δ 1 H-MRI maps were sensitive to ventilation heterogeneity related to gravity dependence in healthy lung and to ventilation impairment in CF lung disease. A high correlation was found between MRI and CT ventilation maps (R 2  = 0.79, P < 0.001). Globally, Δ 1 H-MRI and ΔHU decrease with increasing morphological score (respectively, R 2  = 0.56, P < 0.001 and R 2  = 0.31, P < 0.001). Locally, Δ 1 H-MRI was higher in healthy regions (median 15%) compared to regions with bronchiectasis, air trapping, consolidation, and to segments fed by airways with bronchial wall thickening (P < 0.001)., Data Conclusion: Multivolume noncontrast-enhanced MRI, as a nonionizing imaging modality that can be used on nearly any MRI scanner without specialized equipment or gaseous tracers, may be particularly valuable in CF care, providing a new imaging biomarker to detect early alterations in regional lung structure-function., Level of Evidence: 3 Technical Efficacy: Stage 3 J. MAGN. RESON. IMAGING 2018;48:531-542., (© 2018 International Society for Magnetic Resonance in Medicine.)

Purpose: To demonstrate that ultrashort echo time (UTE) magnetic resonance imaging (MRI) can achieve computed tomography (CT)-like quantification of lung parenchyma in free-breathing, non-sedated neonates. Because infant CTs are used sparingly, parenchymal disease evaluation via UTE MRI has potential for translational impact., Materials and Methods: Two neonatal control cohorts without suspected pulmonary morbidities underwent either a research UTE MRI (n = 5; 1.5T) or a clinically-ordered CT (n = 9). Whole-lung means and anterior-posterior gradients of UTE-measured image intensity (arbitrary units, au, normalized to muscle) and CT-measured density (g/cm 3 ) were compared (Mann-Whitney U-test). Separately, a diseased neonatal cohort (n = 5) with various pulmonary morbidities underwent both UTE MRI and CT. UTE intensity and CT density were compared with Spearman correlations within ∼33 anatomically matched regions of interest (ROIs) in each diseased subject, spanning low- to high-density tissues. Radiological classifications were evaluated in all ROIs, with mean UTE intensities and CT densities compared in each classification., Results: In control subjects, whole-lung UTE intensities (0.51 ± 0.04 au) were similar to CT densities (0.44 ± 0.09 g/cm 3 ) (P = 0.062), as were UTE (0.021 ± 0.020 au/cm) and CT (0.034 ± 0.024 [g/cm 3 ]/cm) anterior-posterior gradients (P = 0.351). In diseased subjects' ROIs, significant correlations were observed between UTE and CT (P ≤0.007 in each case). Relative differences between UTE and CT were small in all classifications (4-25%)., Conclusion: These results demonstrate a strong association between UTE image intensity and CT density, both between whole-lung tissue in control patients and regional radiological pathologies in diseased patients. This indicates the potential for UTE MRI to longitudinally evaluate neonatal pulmonary disease and to provide visualization of pathologies similar to CT, without sedation/anesthesia or ionizing radiation., Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:992-1000., (© 2017 International Society for Magnetic Resonance in Medicine.)