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Rationale: Hemodynamically significant patent ductus arteriosus (hsPDA) in premature infants has been associated with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH). However, these associations remain incompletely understood. Objectives: To assess the associations between hsPDA duration and clinical outcomes, PH, and phenotypic differences on lung magnetic resonance imaging (MRI). Methods: In this retrospective cohort study, we identified all infants with BPD at <32 weeks' gestation who also underwent research lung MRI at <48 weeks' postmenstrual age (PMA) from 2014 to 2022. Clinical echocardiograms were reviewed for hsPDA and categorized as no hsPDA, hsPDA 1-60 days, and hsPDA >60 days. Outcome variables included BPD severity, PH at 36 weeks' PMA, PH after 36 weeks' PMA in the absence of shunt (PH-pulmonary vascular disease [PVD]), tracheostomy or death, and lung phenotype by MRI via modified Ochiai score, indexed total lung volume, and whole-lung hyperdensity. Logistic regression and ANOVA were used. Measurements and Main Results: In total, 133 infants born at 26.2 ± 1.9 weeks, weighing 776 ± 276 g, were reviewed (47 with no hsPDA, 44 with hsPDA 1-60 days, and 42 with hsPDA >60 d). hsPDA duration > 60 days was associated with BPD severity (P < 0.01), PH at 36 weeks' PMA (adjusted odds ratio [aOR], 9.7 [95% confidence interval (CI), 3.3-28.4]), PH-PVD (aOR, 6.5 [95% CI, 2.3-18.3]), and tracheostomy or death (aOR, 3.0 [95% CI, 1.0-8.8]). Duration of hsPDA > 60 days was associated with higher Ochiai score (P = 0.03) and indexed total lung volume (P = 0.01) but not whole-lung hyperdensity (P = 0.91). Conclusions: In infants with moderate or severe BPD, prolonged exposure to hsPDA is associated with BPD severity, PH-PVD, and increased parenchymal lung disease by MRI.
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Displasia Broncopulmonar , Conducto Arterioso Permeable , Hipertensión Pulmonar , Recien Nacido Prematuro , Imagen por Resonancia Magnética , Humanos , Displasia Broncopulmonar/fisiopatología , Displasia Broncopulmonar/diagnóstico por imagen , Displasia Broncopulmonar/complicaciones , Conducto Arterioso Permeable/diagnóstico por imagen , Conducto Arterioso Permeable/fisiopatología , Conducto Arterioso Permeable/complicaciones , Hipertensión Pulmonar/diagnóstico por imagen , Hipertensión Pulmonar/fisiopatología , Masculino , Estudios Retrospectivos , Recién Nacido , Femenino , Imagen por Resonancia Magnética/métodos , Fenotipo , Índice de Severidad de la Enfermedad , Pulmón/diagnóstico por imagen , Pulmón/fisiopatologíaRESUMEN
PURPOSE: To develop a robust 3D ultrashort-TE (UTE) protocol that can reproducibly provide high-quality images, assessed by the ability to yield clinically diagnostic images, and is suitable for clinical translation. THEORY AND METHODS: Building on previous work, a UTE sampled with Fermat looped orthogonally encoded trajectories (FLORET) was chosen as a starting point due to its shorter, clinically reasonable scan times. Modifications to previous FLORET implementations included gradient waveform frequency limitations, a new trajectory ordering scheme, a balanced SSFP implementation, fast gradient spoiling, and full inline reconstruction. FLORET images were collected in phantoms and humans on multiple scanners and sites to demonstrate these improvements. RESULTS: The updates to FLORET provided high-quality images in phantom, musculoskeletal, and pulmonary applications. The gradient waveform modifications and new trajectory ordering scheme significantly reduced visible artifacts. Fast spoiling reduced acquisition time by 20%-28%. Across the various scanners and sites, the inline image quality was consistent and of diagnostic quality. Total image acquisition plus reconstruction time was less than 4 min for musculoskeletal and pulmonary applications with reconstructions taking less than 1 min. CONCLUSION: Recently developed improvements for the FLORET sequence have enabled robust, high-quality UTE acquisitions with short acquisition and reconstruction times. This enables clinical UTE imaging as demonstrated by the implementation of the sequence and acquisition on five MRI scanners, at three different sites, without the need for any additional system characterization or measurements.
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PURPOSE: Xenon-129 (129 Xe) gas-exchange MRI is a pulmonary-imaging technique that provides quantitative metrics for lung structure and function and is often compared to pulmonary-function tests. Unlike such tests, it does not normalize to predictive values based on demographic variables such as age. Many sites have alluded to an age dependence in gas-exchange metrics; however, a procedure for normalizing metrics has not yet been introduced. THEORY: We model healthy reference values for 129 Xe gas-exchange MRI against age using generalized additive models for location, scale, and shape (GAMLSS). GAMLSS takes signal data from an aggregated heathy-reference cohort and fits a distribution with flexible median, variation, skewness, and kurtosis to predict age-dependent centiles. This approach mirrors methods by the Global Lung Function Initiative for modeling pulmonary-function test data and applies it to binning methods widely used by the 129 Xe MRI community to interpret and quantify gas-exchange data. METHODS: Ventilation, membrane-uptake, red blood cell transfer, and red blood cell:membrane gas-exchange metrics were collected on 30 healthy subjects over an age range of 5 to 68 years. A GAMLSS model was fit against age and compared against widely used linear and generalized-linear binning 129 Xe MRI analysis schemes. RESULTS: All 4 gas-exchange metrics had significant skewness, and membrane-uptake had significant kurtosis compared to a normal distribution. Age has significant impact on distribution parameters. GAMLSS-binning produced narrower bins compared to the linear and generalized-linear binning schemes and distributed signal data closer to a normal distribution. CONCLUSION: The proposed "proof-of-concept" GAMLSS-binning approach can improve diagnostic accuracy of 129 Xe gas-exchange MRI by providing a means of modeling voxel distribution data against age.
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Pulmón , Imagen por Resonancia Magnética , Niño , Humanos , Adolescente , Adulto Joven , Preescolar , Adulto , Persona de Mediana Edad , Anciano , Imagen por Resonancia Magnética/métodos , Pulmón/diagnóstico por imagen , Isótopos de Xenón , Pruebas de Función Respiratoria , Respiración , EritrocitosRESUMEN
PURPOSE: The underlying functional and microstructural lung disease in neonates who are born preterm (bronchopulmonary dysplasia, BPD) remains poorly characterized. Moreover, there is a lack of suitable techniques to reliably assess lung function in this population. Here, we report our preliminary experience with hyperpolarized 129 Xe MRI in neonates with BPD. METHODS: Neonatal intensive care patients with established BPD were recruited (N = 9) and imaged at a corrected gestational age of median:40.7 (range:37.1, 44.4) wk using a 1.5T neonatal scanner. 2D 129 Xe ventilation and diffusion-weighted images and dissolved phase spectroscopy were acquired, alongside 1 H 3D radial UTE. 129 Xe images were acquired during a series of short apneic breath-holds (Ë3 s). 1 H UTE images were acquired during tidal breathing. Ventilation defects were manually identified and qualitatively compared to lung structures on UTE. ADCs were calculated on a voxel-wise basis. The signal ratio of the 129 Xe red blood cell (RBC) and tissue membrane (M) resonances from spectroscopy was determined. RESULTS: Spiral-based 129 Xe ventilation imaging showed good image quality and sufficient sensitivity to detect mild ventilation abnormalities in patients with BPD. 129 Xe ADC values were elevated above that expected given healthy data in older children and adults (median:0.046 [range:0.041, 0.064] cm2 s-1 ); the highest value obtained from an extremely pre-term patient. 129 Xe spectroscopy revealed a low RBC/M ratio (0.14 [0.06, 0.21]). CONCLUSION: We have demonstrated initial feasibility of 129 Xe lung MRI in neonates. With further data, the technique may help guide management of infant lung diseases in the neonatal period and beyond.
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Displasia Broncopulmonar , Adulto , Recién Nacido , Niño , Humanos , Displasia Broncopulmonar/diagnóstico por imagen , Estudios de Factibilidad , Isótopos de Xenón , Pulmón/diagnóstico por imagen , Imagen por Resonancia Magnética/métodosRESUMEN
BACKGROUND: Multiple-breath washout (MBW) 129 Xe MRI (MBW Xe-MRI) is a promising technique for following pediatric cystic fibrosis (CF) lung disease progression. However, its repeatability in stable CF needs to be established to use it as an outcome measure for novel therapies. PURPOSE: To assess intravisit and intervisit repeatability of MBW Xe-MRI in healthy and CF children. STUDY TYPE: Prospective, longitudinal cohort study. SUBJECTS: A total of 18 pediatric subjects (7 healthy, 11 CF). FIELD STRENGTH/SEQUENCE: A 3 T/2D coronal hyperpolarized (HP) 129 Xe images using GRE sequence. ASSESSMENT: All subjects completed MBW Xe-MRI, pulmonary function tests (PFTs) (spirometry, nitrogen [N2 ] MBW for lung clearance index [LCI]) and ventilation defect percent (VDP) at baseline (visit 1) and 1-month after. Fractional ventilation (FV), coefficient of variation (CoVFV ) maps were calculated from MBW Xe-MRI data acquired between intervening air washout breaths performed after an initial xenon breath-hold. Skewness of FV and CoVFV map distributions was also assessed. STATISTICAL TESTS: Repeatability: intraclass correlation coefficients (ICC), within-subject coefficient of variation (CV%), repeatability coefficient (CR). Agreement: Bland-Altman. For correlations between MBW Xe-MRI, VDP and PFTs: Spearman's correlation. Significance threshold: P < 0.05. RESULTS: For FV, intravisit median [IQR] ICC was high in both healthy (0.94 [0.48, 0.99]) and CF (0.83 [0.04, 0.97]) subjects. CoVFV also had good intravisit ICC in healthy (0.92 [0.42, 0.99]) and CF (0.79 [0.02, 0.96]) subjects. Similarly, for FV, intervisit ICC was high in health (0.94 [0.68, 0.99]) and CF (0.89 [0.61, 0.97]). CoVFV also had good intervisit ICC in health (0.92 [0.42, 0.99]) and CF (0.78 [0.26, 0.94]). FV had better intervisit repeatability than VDP. CoVFV correlated significantly with LCI (R = 0.56). Skewness of FV distributions significantly distinguished between cohorts at baseline. DATA CONCLUSION: MBW Xe-MRI had high intravisit and intervisit repeatability in healthy and stable CF subjects. CoVFV correlated with LCI, suggesting the importance of ventilation heterogeneity to early CF. EVIDENCE LEVEL: 1. TECHNICAL EFFICACY: Stage 2.
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Fibrosis Quística , Humanos , Niño , Fibrosis Quística/diagnóstico por imagen , Xenón , Estudios Prospectivos , Estudios Longitudinales , Pruebas de Función Respiratoria/métodos , Pulmón/diagnóstico por imagen , Isótopos de Xenón , Imagen por Resonancia Magnética/métodosRESUMEN
RATIONALE: Organ size matching is an important determinant of successful allocation and outcomes in lung transplantation. While computed tomography (CT) is the gold standard, it is rarely used in an organ-donor context, and chest X-ray (CXR) may offer a practical and accurate solution in estimating lung volumes for donor and recipient size matching. We compared CXR lung measurements to CT-measured lung volumes and traditional estimates of lung volume in the same subjects. METHODS: Our retrospective study analyzed clinically obtained CXR and CT lung images of 250 subjects without evidence of lung disease (mean age 9.9 ± 7.8 years; 129 M/121F). From CT, each lung was semi-automatically segmented and total lung volumes were quantified. From anterior-posterior CXR view, each lung was manually segmented and areas were measured. Lung lengths from the apices to the mid-basal regions of each lung were measured from CXR. Quantified CT lung volumes were compared to the corresponding CXR lung lengths, CXR lung areas, height, weight, and predicted total lung capacity (pTLC). RESULTS: There are strong and significant correlations between CT volumes and CXR lung areas in the right lung (R2 = .89, p < .0001), left lung (R2 = .87, p < .0001), and combined lungs (R2 = .89, p < .0001). Similar correlations were seen between CT volumes and CXR measured lung lengths in the right lung (R2 = .79, p < .0001) and left lung (R2 = .81, p < .0001). This correlation between anatomical lung volume (CT) and CXR was stronger than lung-volume correlation to height (R2 = .66, p < .0001), weight (R2 = .43, p < .0001), or pTLC (R2 = .66, p < .0001). CONCLUSION: CXR measures correlate much more strongly with true lung volumes than height, weight, or pTLC. The ability to obtain efficient and more accurate lung volume via CXR has the potential to change our current listing practices of using height as a surrogate for lung size, with a case example provided.
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Trasplante de Pulmón , Pulmón , Humanos , Preescolar , Niño , Adolescente , Estudios Retrospectivos , Rayos X , Pulmón/diagnóstico por imagen , Mediciones del Volumen Pulmonar/métodos , Trasplante de Pulmón/métodosRESUMEN
BACKGROUND: Pulmonary hypertension (PH) is a common complication in patients with alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a severe congenital disorder associated with mutations in the FOXF1 gene. Although the loss of alveolar microvasculature causes PH in patients with ACDMPV, it is unknown whether increasing neonatal lung angiogenesis could prevent PH and right ventricular (RV) hypertrophy. METHODS: We used echocardiography, RV catheterization, immunostaining, and biochemical methods to examine lung and heart remodeling and RV output in Foxf1WT/S52F mice carrying the S52F Foxf1 mutation (identified in patients with ACDMPV). The ability of Foxf1WT/S52F mutant embryonic stem cells to differentiate into respiratory cell lineages in vivo was examined using blastocyst complementation. Intravascular delivery of nanoparticles with a nonintegrating Stat3 expression vector was used to improve neonatal pulmonary angiogenesis in Foxf1WT/S52F mice and determine its effects on PH and RV hypertrophy. RESULTS: Foxf1WT/S52F mice developed PH and RV hypertrophy after birth. The severity of PH in Foxf1WT/S52F mice directly correlated with mortality, low body weight, pulmonary artery muscularization, and increased collagen deposition in the lung tissue. Increased fibrotic remodeling was found in human ACDMPV lungs. Mouse embryonic stem cells carrying the S52F Foxf1 mutation were used to produce chimeras through blastocyst complementation and to demonstrate that Foxf1WT/S52F embryonic stem cells have a propensity to differentiate into pulmonary myofibroblasts. Intravascular delivery of nanoparticles carrying Stat3 cDNA protected Foxf1WT/S52F mice from RV hypertrophy and PH, improved survival, and decreased fibrotic lung remodeling. CONCLUSIONS: Nanoparticle therapies increasing neonatal pulmonary angiogenesis may be considered to prevent PH in ACDMPV.
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Técnicas de Transferencia de Gen , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/terapia , Nanopartículas , Síndrome de Circulación Fetal Persistente/complicaciones , Alveolos Pulmonares/anomalías , Factor de Transcripción STAT3/genética , Remodelación de las Vías Aéreas (Respiratorias)/genética , Animales , Biomarcadores , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Portadores de Fármacos , Sistemas de Liberación de Medicamentos , Ecocardiografía , Fibrosis , Factores de Transcripción Forkhead/deficiencia , Terapia Genética , Humanos , Hipertensión Pulmonar/diagnóstico , Hipertensión Pulmonar/metabolismo , Hipertrofia Ventricular Derecha/diagnóstico , Hipertrofia Ventricular Derecha/etiología , Hipertrofia Ventricular Derecha/metabolismo , Ratones , Ratones Transgénicos , Densidad Microvascular/genética , Miofibroblastos/metabolismo , Síndrome de Circulación Fetal Persistente/genética , Síndrome de Circulación Fetal Persistente/patología , Factor de Transcripción STAT3/administración & dosificación , Nanomedicina Teranóstica/métodos , Resultado del Tratamiento , Remodelación Vascular/genéticaRESUMEN
BACKGROUND: Chest computed tomography (CT) remains the imaging standard for demonstrating cystic fibrosis (CF) airway structural disease in vivo. However, visual scoring systems as an outcome measure are time consuming, require training and lack high reproducibility. Our objective was to validate a fully automated artificial intelligence (AI)-driven scoring system of CF lung disease severity. METHODS: Data were retrospectively collected in three CF reference centres, between 2008 and 2020, in 184 patients aged 4-54â years. An algorithm using three 2D convolutional neural networks was trained with 78 patients' CT scans (23â530 CT slices) for the semantic labelling of bronchiectasis, peribronchial thickening, bronchial mucus, bronchiolar mucus and collapse/consolidation. 36 patients' CT scans (11â435 CT slices) were used for testing versus ground-truth labels. The method's clinical validity was assessed in an independent group of 70 patients with or without lumacaftor/ivacaftor treatment (n=10 and n=60, respectively) with repeat examinations. Similarity and reproducibility were assessed using the Dice coefficient, correlations using the Spearman test, and paired comparisons using the Wilcoxon rank test. RESULTS: The overall pixelwise similarity of AI-driven versus ground-truth labels was good (Dice 0.71). All AI-driven volumetric quantifications had moderate to very good correlations to a visual imaging scoring (p<0.001) and fair to good correlations to forced expiratory volume in 1â s % predicted at pulmonary function tests (p<0.001). Significant decreases in peribronchial thickening (p=0.005), bronchial mucus (p=0.005) and bronchiolar mucus (p=0.007) volumes were measured in patients with lumacaftor/ivacaftor. Conversely, bronchiectasis (p=0.002) and peribronchial thickening (p=0.008) volumes increased in patients without lumacaftor/ivacaftor. The reproducibility was almost perfect (Dice >0.99). CONCLUSION: AI allows fully automated volumetric quantification of CF-related modifications over an entire lung. The novel scoring system could provide a robust disease outcome in the era of effective CF transmembrane conductance regulator modulator therapy.
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Inteligencia Artificial , Regulador de Conductancia de Transmembrana de Fibrosis Quística , Adolescente , Adulto , Aminopiridinas/uso terapéutico , Niño , Preescolar , Humanos , Pulmón/diagnóstico por imagen , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Adulto JovenRESUMEN
RATIONALE: Hyperpolarized (HP) 129 Xe-MRI provides non-invasive methods to quantify lung function and structure, with the 129 Xe apparent diffusion coefficient (ADC) being a well validated measure of alveolar airspace size. However, the experimental factors that impact the precision and accuracy of HP 129 Xe ADC measurements have not been rigorously investigated. Here, we introduce an analytical model to predict the experimental uncertainty of 129 Xe ADC estimates. Additionally, we report ADC dependence on age in healthy pediatric volunteers. METHODS: An analytical expression for ADC uncertainty was derived from the Stejskal-Tanner equation and simplified Bloch equations appropriate for HP media. Parameters in the model were maximum b-value (bmax ), number of b-values (Nb ), number of phase encoding lines (Nph ), flip angle and the ADC itself. This model was validated by simulations and phantom experiments, and five fitting methods for calculating ADC were investigated. To examine the lower range for 129 Xe ADC, 32 healthy subjects (age 6-40 years) underwent diffusion-weighted 129 Xe MRI. RESULTS: The analytical model provides a lower bound on ADC uncertainty and predicts that decreased signal-to-noise ratio yields increases in relative uncertainty (ϵADC) . As such, experimental parameters that impact non-equilibrium 129 Xe magnetization necessarily impact the resulting ϵADC . The values of diffusion encoding parameters (Nb and bmax ) that minimize ϵADC strongly depend on the underlying ADC value, resulting in a global minimum for ϵADC . Bayesian fitting outperformed other methods (error < 5%) for estimating ADC. The whole-lung mean 129 Xe ADC of healthy subjects increased with age at a rate of 1.75 × 10-4 cm2 /s/yr (p = 0.001). CONCLUSIONS: HP 129 Xe diffusion MRI can be improved by minimizing the uncertainty of ADC measurements via uncertainty propagation. Doing so will improve experimental accuracy when measuring lung microstructure in vivo and should allow improved monitoring of regional disease progression and assessment of therapy response in a range of lung diseases.
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Imagen de Difusión por Resonancia Magnética/métodos , Pulmón/diagnóstico por imagen , Isótopos de Xenón , Adolescente , Adulto , Factores de Edad , Niño , Difusión , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Relación Señal-Ruido , Incertidumbre , Adulto JovenRESUMEN
BACKGROUND: 129 Xe gas-transfer MRI provides regional measures of pulmonary gas exchange in adults and separates xenon in interstitial lung tissue/plasma (barrier) from xenon in red blood cells (RBCs). The technique has yet to be demonstrated in pediatric populations or conditions. PURPOSE/HYPOTHESIS: To perform an exploratory analysis of 129 Xe gas-transfer MRI in children. STUDY TYPE: Prospective. POPULATION: Seventy-seven human volunteers (38 males, age = 17.7 ± 15.1 years, range 5-68 years, 16 healthy). Four pediatric disease cohorts. FIELD STRENGTH/SEQUENCE: 3-T, three-dimensional-radial one-point Dixon Fast Field Echo (FFE) Ultrashort Echo Time (UTE). ASSESSMENT: Breath hold compliance was assessed by quantitative signal-to-noise and dynamic metrics. Whole-lung means and standard deviations were extracted from gas-transfer maps. Gas-transfer metrics were investigated with respect to age and lung disease. Clinical pulmonary function tests were retrospectively acquired for reference lung disease severity. STATISTICAL TESTS: Wilcoxon rank-sum tests to compare age and disease cohorts, Wilcoxon signed-rank tests to compare pre- and post-breath hold vitals, Pearson correlations between age and gas-transfer metrics, and limits of normal with a binomial exact test to compare fraction of subjects with abnormal gas-transfer. P ≤ 0.05 was considered significant. RESULTS: Eighty percentage of pediatric subjects successfully completed 129 Xe gas-transfer MRI. Gas-transfer parameters differed between healthy children and adults, including ventilation (0.75 and 0.67) and RBC:barrier ratio (0.31 and 0.46) which also correlated with age (ρ = -0.76, 0.57, respectively). Bone marrow transplant subjects had impaired ventilation (90% of reference) and increased dissolved 129 Xe standard deviation (242%). Bronchopulmonary dysplasia subjects had decreased barrier-uptake (69%). Cystic fibrosis subjects had impaired ventilation (91%) and increased RBC-transfer (146%). Lastly, childhood interstitial lung disease subjects had increased ventilation heterogeneity (113%). Limits of normal provided detection of abnormalities in additional gas-transfer parameters. DATA CONCLUSION: Pediatric 129 Xe gas-transfer MRI was adequately successful and gas-transfer metrics correlated with age. Exploratory analysis revealed abnormalities in a variety of pediatric obstructive and restrictive lung diseases. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.
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Enfermedades Pulmonares , Isótopos de Xenón , Adolescente , Adulto , Anciano , Niño , Preescolar , Estudios de Factibilidad , Humanos , Imagenología Tridimensional/métodos , Recién Nacido , Pulmón/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estudios Retrospectivos , Xenón , Adulto JovenRESUMEN
Background: Premature birth affects millions of neonates each year, placing them at risk for respiratory disease due to prematurity. Bronchopulmonary dysplasia is the most common chronic lung disease of infancy, but recent data suggest that even premature infants who do not meet the strict definition of bronchopulmonary dysplasia can develop adverse pulmonary outcomes later in life. This post-prematurity respiratory disease (PPRD) manifests as chronic respiratory symptoms, including cough, recurrent wheezing, exercise limitation, and reduced pulmonary function. This document provides an evidence-based clinical practice guideline on the outpatient management of infants, children, and adolescents with PPRD. Methods: A multidisciplinary panel of experts posed questions regarding the outpatient management of PPRD. We conducted a systematic review of the relevant literature. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of the clinical recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations were developed for or against three common medical therapies and four diagnostic evaluations in the context of the outpatient management of PPRD. Conclusions: The panel developed recommendations for the outpatient management of patients with PPRD on the basis of limited evidence and expert opinion. Important areas for future research were identified.
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Enfermedades del Prematuro/terapia , Enfermedades Respiratorias/terapia , Adolescente , Cuidados Posteriores , Niño , Enfermedad Crónica , Humanos , Lactante , Recién Nacido , Recien Nacido PrematuroRESUMEN
Bronchopulmonary dysplasia (BPD) is a common long-term complication of preterm birth. The chest radiograph appearance and survivability have evolved since the first description of BPD in 1967 because of improved ventilation and clinical strategies and the introduction of surfactant in the early 1990s. Contemporary imaging care is evolving with the recognition that comorbidities of tracheobronchomalacia and pulmonary hypertension have a great influence on outcomes and can be noninvasively evaluated with CT and MRI techniques, which provide a detailed evaluation of the lungs, trachea and to a lesser degree the heart. However, echocardiography remains the primary modality to evaluate and screen for pulmonary hypertension. This review is intended to highlight the important findings that chest radiograph, CT and MRI can contribute to precision diagnosis, phenotyping and prognosis resulting in optimal management and therapeutics.
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Displasia Broncopulmonar , Hipertensión Pulmonar , Nacimiento Prematuro , Displasia Broncopulmonar/diagnóstico por imagen , Femenino , Humanos , Recién Nacido , Imagen por Resonancia Magnética/efectos adversos , Embarazo , Tomografía Computarizada por Rayos X/efectos adversosRESUMEN
BACKGROUND: Pulmonary arterial hypertension, impaired cardiac function and lung hypoplasia are common in infants with congenital diaphragmatic hernia (CDH) and are associated with increased morbidity and mortality. Robust noninvasive methods to quantify these abnormalities in early infancy are lacking. OBJECTIVE: To determine the feasibility of MRI to quantify cardiopulmonary hemodynamics and function in infants with CDH and to investigate left-right blood flow and lung volume discrepancies. MATERIALS AND METHODS: We conducted a prospective MRI study of 23 neonates (isolated left CDH: 4 pre-repair, 7 post-repair, 3 pre- and post-repair; and 9 controls) performed on a small-footprint 1.5-tesla (T) scanner. We calculated MRI-based pulmonary arterial blood flow, left ventricular eccentricity index, cardiac function and lung volume. Using the Wilcoxon rank sum test for continuous data and Fisher exact test for categorical data, we made pairwise group comparisons. RESULTS: The right-to-left ratios for pulmonary artery blood flow and lung volume were elevated in pre-repair and post-repair CDH versus controls (flow: P<0.005; volume: P<0.05 pre-/post-repair). Eccentricity index at end-systole significantly differed between pre-repair and post-repair CDH (P<0.01) and between pre-repair CDH and controls (P<0.001). CONCLUSION: Cardiopulmonary MRI is a viable method to serially evaluate cardiopulmonary hemodynamics and function in critically ill infants and is useful for capturing left-right asymmetries in pulmonary blood flow and lung volume.
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Hernias Diafragmáticas Congénitas , Recién Nacido , Lactante , Humanos , Hernias Diafragmáticas Congénitas/diagnóstico por imagen , Hernias Diafragmáticas Congénitas/complicaciones , Estudios Prospectivos , Pulmón/anomalías , Mediciones del Volumen Pulmonar , Imagen por Resonancia Magnética/métodosRESUMEN
BACKGROUND: Measurement of regional lung ventilation with hyperpolarized 129Xe magnetic resonance imaging (129Xe MRI) in pediatric asthma is poised to advance our understanding of disease mechanisms and pathophysiology in a disorder with diverse clinical phenotypes. 129Xe MRI has not been investigated in a pediatric asthma cohort. OBJECTIVE: We hypothesized that 129Xe MRI is feasible and can demonstrate ventilation defects that relate to and predict clinical severity in a pediatric asthma cohort. METHODS: Thirty-seven children (13 with severe asthma, 8 with mild/moderate asthma, 16 age-matched healthy controls) aged 6 to 17 years old were imaged with 129Xe MRI. Ventilation defect percentage (VDP) and image reader score were calculated and compared with clinical measures at baseline and at follow-up. RESULTS: Children with asthma had higher VDP (P = .002) and number of defects per image slice (defects/slice) (P = .0001) than children without asthma. Children with clinically severe asthma had significantly higher VDP and number of defects/slice than healthy controls. Children with asthma who had a higher number of defects/slice had a higher rate of health care utilization (r = 0.48; P = .03) and oral corticosteroid use (r = 0.43; P = .05) at baseline. Receiver-operating characteristic analysis demonstrated that the VDP and number of defects/slice were predictive of increased health care utilization, asthma, and severe asthma. VDP correlated with FEV1 (r = -0.35; P = .04) and FEV1/forced vital capacity ratio (r = -0.41; P = .01). CONCLUSIONS: 129Xe MRI correlates with asthma severity, health care utilization, and oral corticosteroid use. Because delineation of clinical severity is often difficult in children, 129Xe MRI may be an important biomarker for severity, with potential to identify children at higher risk for exacerbations and improve outcomes.
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Asma/diagnóstico , Medios de Contraste , Imagen por Resonancia Magnética/métodos , Isótopos de Xenón , Adolescente , Asma/terapia , Estudios de Casos y Controles , Niño , Femenino , Humanos , Masculino , Curva ROC , Pruebas de Función Respiratoria , Índice de Severidad de la EnfermedadRESUMEN
PURPOSE: Hyperpolarized xenon (129 Xe) gas-transfer imaging allows different components of pulmonary gas transfer-alveolar air space, lung interstitium/blood plasma (barrier), and red blood cells (RBCs)-to be assessed separately in a single breath. However, quantitative analysis is challenging because dissolved-phase 129 Xe images are often contaminated by off-resonant gas-phase signal generated via imperfectly selective excitation. Although previous methods required additional data for gas-phase removal, the method reported here requires no/minimal sequence modifications/data acquisitions, allowing many previously acquired images to be corrected retroactively. METHODS: 129 Xe imaging was implemented at 3.0T via an interleaved three-dimensional radial acquisition of the gaseous and dissolved phases (using one-point Dixon reconstruction for the dissolved phase) in 46 human subjects and a phantom. Gas-phase contamination (9.5% ± 4.8%) was removed from gas-transfer data using a modified gas-phase image. The signal-to-noise ratio (SNR) and signal distributions were compared before and after contamination removal. Additionally, theoretical gaseous contaminations were simulated at different magnetic field strengths for comparison. RESULTS: Gas-phase contamination at 3.0T was more diffuse and located predominantly outside the lungs, relative to simulated 1.5T contamination caused by the larger frequency offset. Phantom experiments illustrated a 91% removal efficiency. In human subjects, contamination removal produced significant changes in dissolved signal SNR (+7.8%), mean (-1.4%), and standard deviation (-2.3%) despite low contamination. Repeat measurements showed reduced variance (dissolved mean, -1.0%; standard deviation, -8.4%). CONCLUSION: Off-resonance gas-phase contamination can be removed robustly with no/minimal sequence modifications. Contamination removal permits more accurate quantification, reduces radiofrequency stringency requirements, and increases data consistency, providing improved sensitivity needed for multicenter trials.
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Artefactos , Isótopos de Xenón , Humanos , Pulmón/diagnóstico por imagen , Imagen por Resonancia Magnética , XenónRESUMEN
PURPOSE: Diffusion and lung morphometry imaging using hyperpolarized gases are promising tools to quantify pulmonary microstructure noninvasively in humans and in animal models. These techniques assume the motion encoded is exclusively diffusive gas displacement, but the impact of cardiac motion on measurements has never been explored. Furthermore, although diffusion morphometry has been validated against histology in humans and mice using 3 He, it has never been validated in mice for 129 Xe. Here, we examine the effect of cardiac motion on diffusion imaging and validate 129 Xe diffusion morphometry in mice. THEORY AND METHODS: Mice were imaged using gradient-echo-based diffusion imaging, and apparent diffusion-coefficient (ADC) maps were generated with and without cardiac gating. Diffusion-weighted images were fit to a previously developed theoretical model using Bayesian probability theory, producing morphometric parameters that were compared with conventional histology. RESULTS: Cardiac gating had no significant impact on ADC measurements (dual-gating: ADC = 0.020 cm2 /s, single-gating: ADC = 0.020 cm2 /s; P = .38). Diffusion-morphometry-generated maps of ADC (mean, 0.0165 ± 0.0001 cm2 /s) and acinar dimensions (alveolar sleeve depth [h] = 44 µm, acinar duct radii [R] = 99 µm, mean linear intercept [Lm ] = 74 µm) that agreed well with conventional histology (h = 45 µm, R = 108 µm, Lm = 63 µm). CONCLUSION: Cardiac motion has negligible impact on 129 Xe ADC measurements in mice, arguing its impact will be similarly minimal in humans, where relative cardiac motion is reduced. Hyperpolarized 129 Xe diffusion morphometry accurately and noninvasively maps the dimensions of lung microstructure, suggesting it can quantify the pulmonary microstructure in mouse models of lung disease.
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Imagen de Difusión por Resonancia Magnética , Isótopos de Xenón , Animales , Teorema de Bayes , Difusión , Helio , Pulmón/diagnóstico por imagen , Masculino , RatonesRESUMEN
Hyperpolarized (HP) 129 Xe MRI uniquely images pulmonary ventilation, gas exchange, and terminal airway morphology rapidly and safely, providing novel information not possible using conventional imaging modalities or pulmonary function tests. As such, there is mounting interest in expanding the use of biomarkers derived from HP 129 Xe MRI as outcome measures in multi-site clinical trials across a range of pulmonary disorders. Until recently, HP 129 Xe MRI techniques have been developed largely independently at a limited number of academic centers, without harmonizing acquisition strategies. To promote uniformity and adoption of HP 129 Xe MRI more widely in translational research, multi-site trials, and ultimately clinical practice, this position paper from the 129 Xe MRI Clinical Trials Consortium (https://cpir.cchmc.org/XeMRICTC) recommends standard protocols to harmonize methods for image acquisition in HP 129 Xe MRI. Recommendations are described for the most common HP gas MRI techniques-calibration, ventilation, alveolar-airspace size, and gas exchange-across MRI scanner manufacturers most used for this application. Moreover, recommendations are described for 129 Xe dose volumes and breath-hold standardization to further foster consistency of imaging studies. The intention is that sites with HP 129 Xe MRI capabilities can readily implement these methods to obtain consistent high-quality images that provide regional insight into lung structure and function. While this document represents consensus at a snapshot in time, a roadmap for technical developments is provided that will further increase image quality and efficiency. These standardized dosing and imaging protocols will facilitate the wider adoption of HP 129 Xe MRI for multi-site pulmonary research.
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Pulmón , Isótopos de Xenón , Pulmón/diagnóstico por imagen , Imagen por Resonancia Magnética , Estudios Multicéntricos como Asunto , Ventilación Pulmonar , RespiraciónRESUMEN
OBJECTIVES: To assess the feasibility of magnetic resonance imaging (MRI) for postnatal assessment of pulmonary vascularity in infants with congenital diaphragmatic hernia (CDH). STUDY DESIGN: Infants with prenatally diagnosed CDH (n = 24) received postnatal pulmonary MRI. Infants with nonpulmonary birth defects served as controls (n = 5). Semiautomatic segmentation was performed to obtain total vascular volume using time of flight images to assess vascularity. RESULTS: Average vascular density (vascular volume/lung volume) in control infants was 0.23 ± 0.06 mm3/mm3 compared with 0.18 ± 0.06 mm3/mm3 in infants with CDH is (P = .09). When stratified further based on CDH severity, the difference between control infants and moderate CDH group was statistically significant. (0.23 mm3/mm3 vs 0.15 mm3/mm3, P = .01). Ipsilateral vascular density on MRI in infants with CDH significantly correlated with the prenatal pulmonary hypertensive index (P = .0004, Spearman R = +0.87) and with number of days on mechanical ventilation (P = .04, Spearman R = -0.44), total days on inhaled nitric oxide (P = .02, Spearman R = -0.47), use of epoprostenol for acute pulmonary hypertension (PH) (0.14 mm3/mm3 vs 0.20 mm3/mm3, P = .005), and use of sildenafil for chronic PH (0.15 mm3/mm3 vs 0.19 mm3/mm3, P = .03). CONCLUSIONS: Our results suggest that postnatal pulmonary vascularity assessed by MRI strongly correlates with prenatal and postnatal markers of PH severity and that pulmonary vascularity may serve as a direct measure of pulmonary vascular hypoplasia in infants with CDH.
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Hernias Diafragmáticas Congénitas/diagnóstico por imagen , Hipertensión Pulmonar/diagnóstico por imagen , Mediciones del Volumen Pulmonar/métodos , Estudios de Casos y Controles , Femenino , Humanos , Recién Nacido , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Índice de Severidad de la EnfermedadRESUMEN
Rationale: Bronchopulmonary dysplasia is a heterogeneous lung disease characterized by regions of cysts and fibrosis, but methods for evaluating lung function are limited to whole lung rather than specific regions of interest.Objectives: Respiratory-gated, ultrashort echo time magnetic resonance imaging was used to test the hypothesis that cystic regions of the lung will exhibit a quantifiable Vt that will correlate with ventilator settings and clinical outcomes.Methods: Magnetic resonance images of 17 nonsedated, quiet-breathing infants with severe bronchopulmonary dysplasia were reconstructed into end-inspiration and end-expiration images. Cysts were identified and measured by using density threshold combined with manual identification and segmentation. Regional Vts were calculated by subtracting end-expiration from end-inspiration volumes in total lung, noncystic lung, total-cystic lung, and individual large cysts.Measurements and Main Results: Cystic lung areas averaged larger Vts than noncystic lung when normalized by volume (0.8 ml Vt/ml lung vs. 0.1 ml Vt/ml lung, P < 0.002). Cyst Vt correlates with cyst size (P = 0.012 for total lung cyst and P < 0.002 for large cysts), although there was variability between individual cyst Vt, with 22% of cysts demonstrating negative Vt. Peak inspiratory pressure positively correlated with total lung Vt (P = 0.027) and noncystic Vt (P = 0.015) but not total lung cyst Vt (P = 0.8). Inspiratory time and respiratory rate did not improve Vt of any analyzed lung region.Conclusions: Cystic lung has greater normalized Vt when compared with noncystic lung. Ventilator pressure increases noncystic lung Vt, but inspiratory time does not correlate with Vt of normal or cystic lung.
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Displasia Broncopulmonar/diagnóstico por imagen , Quistes/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Respiración Artificial/métodos , Volumen de Ventilación Pulmonar/fisiología , Displasia Broncopulmonar/fisiopatología , Displasia Broncopulmonar/terapia , Quistes/fisiopatología , Femenino , Humanos , Imagenología Tridimensional , Lactante , Recien Nacido Extremadamente Prematuro , Recién Nacido , Masculino , Técnicas de Imagen Sincronizada RespiratoriasRESUMEN
Rationale: Patients with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH) have increased morbidity and mortality. Noninvasive assessment relies on echocardiograms (echos), which are technically challenging in this population. Improved assessment could augment decisions regarding PH therapies.Objectives: We hypothesized that neonatal cardiac magnetic resonance imaging (MRI) will correlate with BPD severity and predict short-term clinical outcomes, including need for PH therapies for infants with BPD.Methods: A total of 52 infants (31 severe BPD, 9 moderate BPD, and 12 with either mild or no BPD) were imaged between 39 and 47 weeks postmenstrual age on a neonatal-sized, neonatal ICU-sited 1.5-T magnetic resonance (MR) scanner. MR left ventricular eccentricity index (EI), main pulmonary artery-to-aorta (PA/AO) diameter ratio, and pulmonary arterial blood flow were determined. Echos obtained for clinical indications were reviewed. MRI and echo indices were compared with BPD severity and clinical outcomes, including length of stay (LOS), duration of respiratory support, respiratory support at discharge, and PH therapy.Measurements and Main Results: PA/AO ratio increased with BPD severity. Increased PA/AO ratio, MR-EI, and echo-EIs were associated with increased LOS and duration of respiratory support. No correlation was seen between pulmonary arterial blood flow and BPD outcomes. Controlling for gestational age, birth weight, and BPD severity, MR-EI was associated with LOS and duration of respiratory support. Increased PA/AO ratio and MR-EI were associated with PH therapy during hospitalization and at discharge.Conclusions: MRI can provide important image-based measures of cardiac morphology that relate to disease severity and clinical outcomes in neonates with BPD.