Initial feasibility and challenges of hyperpolarized Xe MRI in neonates with bronchopulmonary dysplasia.

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 Xe MRI in neonates with BPD.

Longitudinal Lung Function Assessment of Patients Hospitalized With COVID-19 Using H and Xe Lung MRI.

Background: Microvascular abnormalities and impaired gas transfer have been observed in patients with COVID-19. The progression of pulmonary changes in these patients remains unclear.

Research Question: Do patients hospitalized with COVID-19 without evidence of architectural distortion on structural imaging exhibit longitudinal improvements in lung function measured by using H and Xe MRI between 6 and 52 weeks following hospitalization?

Study Design And Methods: Patients who were hospitalized with COVID-19 pneumonia underwent a pulmonary H and Xe MRI protocol at 6, 12, 25, and 51 weeks following hospital admission in a prospective cohort study between November 2020 and February 2022.

Hyperpolarized Xe imaging of the brain: Achievements and future challenges.

Hyperpolarized (HP) xenon-129 ( Xe) brain MRI is a promising imaging modality currently under extensive development. HP Xe is nontoxic, capable of dissolving in pulmonary blood, and is extremely sensitive to the local environment. After dissolution in the pulmonary blood, HP Xe travels with the blood flow to the brain and can be used for functional imaging such as perfusion imaging, hemodynamic response detection, and blood-brain barrier permeability assessment.

Measuring Xe transfer across the blood-brain barrier using MR spectroscopy.

Purpose: This study develops a tracer kinetic model of xenon uptake in the human brain to determine the transfer rate of inhaled hyperpolarized Xe from cerebral blood to gray matter that accounts for the effects of cerebral physiology, perfusion and magnetization dynamics. The Xe transfer rate is expressed using a tracer transfer coefficient, which estimates the quantity of hyperpolarized Xe dissolved in cerebral blood under exchange with depolarized Xe dissolved in gray matter under equilibrium of concentration.

Theory And Methods: Time-resolved MR spectra of hyperpolarized Xe dissolved in the human brain were acquired from three healthy volunteers.

Comparison of quantitative multiple-breath specific ventilation imaging using colocalized 2D oxygen-enhanced MRI and hyperpolarized He MRI.

Two magnetic resonance specific ventilation imaging (SVI) techniques, namely, oxygen-enhanced proton (OE-H) and hyperpolarized He (HP-He), were compared in eight healthy supine subjects [age 32 (6) yr]. An in-house radio frequency coil array for H configured with the He transmit-receive coil in situ enabled acquisition of SVI data from two nuclei from the same slice without repositioning the subjects. After 3 × 3 voxel downsampling to account for spatial registration errors between the two SV images, the voxel-by-voxel correlation coefficient of two SV maps ranged from 0.

Imaging Human Brain Perfusion with Inhaled Hyperpolarized Xe MR Imaging.

Purpose To evaluate the feasibility of directly imaging perfusion of human brain tissue by using magnetic resonance (MR) imaging with inhaled hyperpolarized xenon 129 (Xe). Materials and Methods In vivo imaging with Xe was performed in three healthy participants. The combination of a high-yield spin-exchange optical pumping Xe polarizer, custom-built radiofrequency coils, and an optimized gradient-echo MR imaging protocol was used to achieve signal sensitivity sufficient to directly image hyperpolarized Xe dissolved in the human brain.