Objective: To compare the cardiopulmonary effects of apneustic anesthesia ventilation (AAV) and conventional mechanical ventilation (CMV) in anesthetized pigs and to describe a new mode of ventilation for anesthetized veterinary species.
Study Design: Randomized, crossover design without washout.
Animals: Twelve healthy, female white Landrace pigs.
Hyperpolarized (HP) xenon magnetic resonance imaging (Xe MRI) is a recently federal drug administration (FDA)-approved imaging modality that produces high-resolution images of an inhaled breath of xenon gas for investigation of lung function. However, implementing Xe MRI is uniquely challenging as it requires specialized hardware and equipment for hyperpolarization, procurement of xenon imaging coils and coil software, development and compilation of multinuclear MR imaging sequences, and reconstruction/analysis of acquired data. Without proper expertise, these tasks can be daunting, and failure to acquire high-quality images can be frustrating, and expensive.
View Article and Find Full Text PDFRationale And Objectives: The current clinical standard for functional imaging of patients with lung ailments is nuclear medicine scintigraphy and Single Photon Emission Computed Tomography (SPECT) which detect the gamma decay of inhaled radioactive tracers. Hyperpolarized (HP) Xenon-129 MRI (XeMRI) of the lungs has recently been FDA approved and provides similar functional images of the lungs with higher spatial resolution than scintigraphy and SPECT. Here we compare Technetium-99m (Tc) diethylene-triamine-pentaacetate scintigraphy and SPECT with HP XeMRI in healthy controls, asthma, and chronic obstructive pulmonary disorder (COPD) patients.
View Article and Find Full Text PDFRationale And Objectives: To support cardiac MR acquisitions during breathing without ECG, we developed software to mitigate the effects of respiratory displacement of the heart. The algorithm resolves respiratory motions and cardiac cycles from DICOM files. The new software automatically detects heartbeats from expiration and inspiration to decrease apparent respiratory motion.
View Article and Find Full Text PDFHyperpolarized Xe MRI (Xe-MRI) is increasingly used to image the structure and function of the lungs. Because Xe imaging can provide multiple contrasts (ventilation, alveolar airspace size, and gas exchange), imaging often occurs over several breath-holds, which increases the time, expense, and patient burden of scans. We propose an imaging sequence that can be used to acquire Xe-MRI gas exchange and high-quality ventilation images within a single, approximately 10 s, breath-hold.
View Article and Find Full Text PDFRationale: Hyperpolarized (HP) Xe-MRI provides non-invasive methods to quantify lung function and structure, with the 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 Xe ADC measurements have not been rigorously investigated. Here, we introduce an analytical model to predict the experimental uncertainty of Xe ADC estimates.
View Article and Find Full Text PDFHyperpolarized (HP) 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 Xe MRI as outcome measures in multi-site clinical trials across a range of pulmonary disorders. Until recently, HP Xe MRI techniques have been developed largely independently at a limited number of academic centers, without harmonizing acquisition strategies.
View Article and Find Full Text PDFComputational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard.
View Article and Find Full Text PDFPurpose: In this study, we compared hyperpolarized He and Xe images from patients with cystic fibrosis using two commonly applied magnetic resonance sequences, standard gradient echo (GRE) and balanced steady-state free precession (TrueFISP) to quantify regional similarities and differences in signal distribution and defect analysis.
Materials And Methods: Ten patients (7M/3F) with cystic fibrosis underwent hyperpolarized gas MR imaging with both He and Xe. Six had MRI with both GRE, and TrueFISP sequences and four patients had only GRE sequence but not TrueFISP.
Background: Alveolar development and lung parenchymal simplification are not well characterized in vivo in neonatal patients with respiratory morbidities, such as bronchopulmonary dysplasia (BPD). Hyperpolarized (HP) gas diffusion magnetic resonance imaging (MRI) is a sensitive, safe, nonionizing, and noninvasive biomarker for measuring airspace size in vivo but has not yet been implemented in young infants.
Objective: This work quantified alveolar airspace size via HP gas diffusion MRI in healthy and diseased explanted infant lung specimens, with comparison to histological morphometry.
Adolescent idiopathic scoliosis (AIS) is associated with decreased respiratory quality of life and impaired diaphragm function. Recent hyperpolarized helium (HHe) MRI studies show alveolarization continues throughout adolescence, and mechanical forces are known to impact alveolarization. We therefore hypothesized that patients with AIS would have alterations in alveolar size, alveolar number, or alveolar septal dimensions compared to adolescents without AIS, and that posterior spinal fusion (PSF) might reverse these differences.
View Article and Find Full Text PDFAdverse events have limited the use of bronchial thermoplasty (BT) in severe asthma. We sought to evaluate the effectiveness and safety of using Xe magnetic resonance imaging (Xe MRI) to prioritize the most involved airways for guided BT. Thirty subjects with severe asthma were imaged with volumetric computed tomography and Xe MRI to quantitate segmental ventilation defects.
View Article and Find Full Text PDFFast apparent transverse relaxation (short T *) is a common obstacle when attempting to perform quantitative H MRI of the lungs. While T * times are longer for pulmonary hyperpolarized (HP) gas functional imaging (in particular for gaseous Xe), T * can still lead to quantitative inaccuracies for sequences requiring longer echo times (such as diffusion weighted images) or longer readout duration (such as spiral sequences). This is especially true in preclinical studies, where high magnetic fields lead to shorter relaxation times than are typically seen in human studies.
View Article and Find Full Text PDFLymphangioleiomyomatosis (LAM) is a rare disease associated with cystic destruction of the pulmonary parenchyma and chronic respiratory failure, and there are trials underway to determine if early intervention can prevent disease progression. An imaging technique that is sensitive to early regional disease would therefore be valuable for patient care and clinical trials. We postulated that hyperpolarized Xe MRI would be sensitive to ventilation abnormalities and alveolar airspace dilation in patients with mild LAM disease and normal pulmonary function and that Xe MRI would reveal important features of cyst ventilation.
View Article and Find Full Text PDFBackground: The ventilation defect percent (VDP), measured from hyperpolarized (HP) Xe magnetic resonance imaging (MRI), is sensitive to functional changes in cystic fibrosis (CF) lung disease. The purpose of this study was to measure and compare VDP from HP Xe MRI acquired at two institutions in stable pediatric CF subjects with preserved lung function.
Methods: This retrospective analysis included 26 participants from two institutions (18 CF, 8 healthy, age range 10-17).
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.
Background: Hyperpolarized Xe is a promising contrast agent for MRI of pediatric lung function, but its safety and tolerability in children have not been rigorously assessed.
Objective: To assess the feasibility, safety and tolerability of hyperpolarized Xe gas as an inhaled contrast agent for pediatric pulmonary MRI in healthy control subjects and in children with cystic fibrosis.
Materials And Methods: Seventeen healthy control subjects (ages 6-15 years, 11 boys) and 11 children with cystic fibrosis (ages 8-16 years, 4 boys) underwent Xe MRI, receiving up to three doses of Xe gas prepared by either a commercially available or a homebuilt Xe polarizer.
Background: Cystic fibrosis (CF) is a genetic disease which carries high morbidity and mortality from lung-function decline. Monitoring disease progression and treatment response in young patients is desirable, but serial imaging via CT is often considered prohibitive, and detailed functional information cannot be obtained using conventional imaging techniques. Hyperpolarized Xe magnetic resonance imaging (MRI) can depict and quantify regional ventilation, but has not been investigated in pediatrics.
View Article and Find Full Text PDFPurpose: To determine the feasibility of pulmonary magnetic resonance imaging (MRI) of neonatal lung structures enabled by combining two novel technologies: first, a 3D radial ultrashort echo time (UTE) pulse sequence capable of high spatial resolution full-chest imaging in nonsedated quiet-breathing neonates; and second, a unique, small-footprint 1.5T MRI scanner design adapted for neonatal imaging and installed within the neonatal intensive care unit (NICU).
Materials And Methods: Ten patients underwent MRI within the NICU, in accordance with an approved Institutional Review Board protocol.
Purpose: To further validate the ability of ultrashort echo-time (UTE) magnetic resonance imaging (MRI) in quantifying lung density in patients diagnosed with chronic obstructive pulmonary disease (COPD) and to develop an MRI-based emphysema index (EI).
Materials And Methods: Ten subjects clinically diagnosed with COPD (5M/5F, age 62.6 ± 8.
Purpose: To implement pulmonary three-dimensional (3D) radial ultrashort echo-time (UTE) MRI in non-sedated, free-breathing neonates and adults with retrospective motion tracking of respiratory and intermittent bulk motion, to obtain diagnostic-quality, respiratory-gated images.
Methods: Pulmonary 3D radial UTE MRI was performed at 1.5 tesla (T) during free breathing in neonates and adult volunteers for validation.
Purpose: Chronic obstructive pulmonary disease (COPD) is an irreversible lung disease characterized by small-airway obstruction and alveolar-airspace destruction. Hyperpolarized Xe diffusion MRI of lung is a promising biomarker for assessing airspace enlargement, but has yet to be validated by direct comparison to lung histology. Here we have compared diffusion measurements of hyperpolarized (HP) Xe in explanted lungs to regionally matched morphological measures of airspace size.
View Article and Find Full Text PDFRationale: Bronchopulmonary dysplasia (BPD) is a prevalent yet poorly characterized pulmonary complication of premature birth; the current definition is based solely on oxygen dependence at 36 weeks postmenstrual age without objective measurements of structural abnormalities across disease severity.
Objectives: We hypothesize that magnetic resonance imaging (MRI) can spatially resolve and quantify the structural abnormalities of the neonatal lung parenchyma associated with premature birth.
Methods: Using a unique, small-footprint, 1.
Purpose: To quantify regional lung ventilation in healthy volunteers and patients with severe asthma (both before and after thermoplasty) by using a combination of helium 3 ((3)He) magnetic resonance (MR) imaging and computed tomography (CT), with the intention of developing more effective image-guided treatments for obstructive lung diseases.
Materials And Methods: With approval of the local institutional review board, informed consent, and an Investigational New Drug Exemption, six healthy volunteers and 10 patients with severe asthma were imaged in compliance with HIPAA regulations by using both multidetector CT and (3)He MR imaging. Individual bronchopulmonary segments were labeled voxel by voxel from the CT images and then registered to the (3)He MR images by using custom software.