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Purpose\ud \ud This study describes the development and testing of an asymmetrical xenon-129 (129Xe) birdcage radiofrequency (RF) coil for 129Xe lung ventilation imaging at 1.5 Tesla, which allows proton (1H) system body coil transmit–receive functionality.\ud \ud \ud Methods\ud \ud The 129Xe RF coil is a whole-body asymmetrical elliptical birdcage constructed without an outer RF shield to enable 1H imaging. urn:x-wiley:07403194:media:mrm28915:mrm28915-math-0001 field homogeneity and flip angle mapping of the 129Xe birdcage RF coil and 1H system body RF coil with the 129Xe RF coil in situ were evaluated in the MR scanner. The functionality of the 129Xe birdcage RF coil was demonstrated through hyperpolarized 129Xe lung ventilation imaging with the birdcage in both transceiver configuration and transmit-only configuration when combined with an 8-channel 129Xe receive-only RF coil array. The functionality of 1H system body coil with the 129Xe RF coil in situ was demonstrated by acquiring coregistered 1H lung anatomical MR images.\ud \ud \ud Results\ud \ud The asymmetrical birdcage produced a homogeneous urn:x-wiley:07403194:media:mrm28915:mrm28915-math-0002 field (±10%) in agreement with electromagnetic simulations. Simulations indicated an optimal detuning configuration with 4 diodes. The obtained g-factor of 1.4 for acceleration factor of R = 2 indicates optimal array configuration. Coregistered 1H anatomical images from the system body coil along with 129Xe lung images demonstrated concurrent and compatible arrangement of the RF coils.\ud \ud \ud Conclusion\ud \ud A large asymmetrical birdcage for homogenous urn:x-wiley:07403194:media:mrm28915:mrm28915-math-0003 transmission with high sensitivity reception for 129Xe lung MRI at 1.5 Tesla has been demonstrated. The unshielded asymmetrical birdcage design enables 1H structural lung MR imaging in the same exam.

Purpose\ud \ud This work assesses the accuracy of the stretched exponential (SEM) and cylinder models of lung microstructural length scales that can be derived from hyperpolarized gas DWI. This was achieved by simulating 3He and 129Xe DWI signals within two micro‐CT–derived realistic acinar airspace meshes that represent healthy and idiopathic pulmonary fibrosis lungs.\ud \ud \ud Methods\ud \ud The healthy and idiopathic pulmonary fibrosis acinar airway meshes were derived from segmentations of 3D micro‐CT images of excised human lungs and meshed for finite element simulations of the Bloch‐Torrey equations. 3He and 129Xe multiple b value DWI experiments across a range of diffusion times (3He Δ = 1.6 ms; 129Xe Δ = 5 to 20 ms) were simulated in each mesh. Global SEM mean diffusive length scale and cylinder model mean chord length value was derived from each finite element simulation and compared against each mesh’s mean linear intercept length, calculated from intercept length measurements within micro‐CT segmentation masks.\ud \ud \ud Results\ud \ud The SEM‐derived mean diffusive length scale was within ±10% of the mean linear intercept length for simulations with both 3He (Δ = 1.6 ms) and 129Xe (Δ = 7 to 13 ms) in the healthy mesh, and with 129Xe (Δ = 13 to 20 ms) for the idiopathic pulmonary fibrosis mesh, whereas for the cylinder model–derived mean chord length the closest agreement with mean linear intercept length (11.7% and 22.6% difference) was at 129Xe Δ = 20 ms for both healthy and IPF meshes, respectively.\ud \ud \ud Conclusion\ud \ud This work validates the use of the SEM for accurate estimation of acinar dimensions and indicates that the SEM is relatively robust across a range of experimental conditions and acinar length scales.

Purpose: To measure the transverse relaxation time (T2) and apparent diffusion co-efficient (ADC) of 19F-C3F8 gas in vivo in human lungs at 1.5T and 3T, and to de-termine the representative distribution of values of these parameters in a cohort of healthy volunteers.\ud Methods: Mapping of ADC at lung inflation levels of functional residual capacity (FRC) and total lung capacity (TLC) was performed with inhaled 19F-C3F8 (eight subjects) and 129Xe (six subjects) at 1.5T. T2 mapping with 19F-C3F8 was performed at 1.5T (at FRC and TLC) for 8 subjects and at 3T (at TLC for seven subjects).\ud Results: At both FRC and TLC, the 19F-C3F8 ADC was smaller than the free dif-fusion coefficient demonstrating airway microstructural diffusion restriction. From FRC to TLC, the mean ADC significantly increased from 1.56 mm2/s to 1.83 mm2/s (P = .0017) for 19F-C3F8, and from 2.49 mm2/s to 3.38 mm2/s (P = .0015) for 129Xe. The posterior-to-anterior gradient in ADC for FRC versus TLC in the superior half of the lungs was measured as 0.0308 mm2/s per cm versus 0.0168 mm2/s per cm for 19F-C3F8 and 0.0871 mm2/s per cm versus 0.0326 mm2/s per cm for 129Xe. A con-sistent distribution of 19F-C3F8 T2 values was observed in the lungs, with low values observed near the diaphragm and large pulmonary vessels. The mean T2 across vol-unteers was 4.48 ms at FRC and 5.33 ms at TLC for 1.5T, and 3.78 ms at TLC for 3T.\ud Conclusion: In this feasibility study, values of physiologically relevant parameters of lung microstructure measurable by MRI (T2, and ADC) were established for C3F8 in vivo lung imaging in healthy volunteers.

Purpose\ud Imaging of the different resonances of dissolved hyperpolarized xenon‐129 (129Xe) in the lung is performed using a four‐echo flyback 3D radial spectroscopic imaging technique and is evaluated in healthy volunteers (HV) and subjects with idiopathic pulmonary fibrosis (IPF).\ud \ud Theory and Methods\ud 10 HV and 25 subjects with IPF underwent dissolved 129Xe MRI at 1.5T. IPF subjects underwent same day pulmonary function tests to measure forced vital capacity and the diffusion capacity of the lung for carbon monoxide (DLCO). A four‐point echo time technique with k‐space chemical‐shift modeling of gas, dissolved 129Xe in lung tissue/plasma (TP) and red blood cells (RBC) combined with a 3D radial trajectory was implemented within a 14‐s breath‐hold.\ud \ud Results\ud Results show an excellent chemical shift separation of the dissolved 129Xe compartments and gas contamination removal, confirmed by a strong agreement between average imaging and global spectroscopy RBC/TP ratio measurements. Subjects with IPF exhibited reduced imaging gas transfer when compared to HV. A significant increase of the amplitude of RBC signal cardiogenic oscillation was also observed. In IPF subjects, DLCO% predicted was significantly correlated with RBC/TP and RBC/GAS ratios and the correlations were stronger in the inferior and periphery sections of the lungs.\ud \ud Conclusion\ud Lung MRI of dissolved 129Xe was performed with a four‐echo spectroscopic imaging method. Subjects with IPF demonstrated reduced xenon imaging gas transfer and increased cardiogenic modulation of dissolved xenon signal in the RBCs when compared to HV.

Peer popularity constitutes a pivotal developmental task to adolescents’ current and future adaptation. This study identified distinct adolescent popularity profiles and explored their links with excessive Internet usage and interpersonal sensitivity. The sample included 2090 students attending Greek high schools (Mage = 16.16, SD = 0.91). Their popularity was measured via self-report and peer sociometric means. They also responded to the Internet Addiction Test (IAT) and the Interpersonal Sensitivity subscale of the Symptom Checklist-90-Revised (SCL-90-R). A sequence of latent profile analysis, ANOVAs and linear regression models were performed. Three distinct popularity profiles were revealed: the “Average Confident” (68.4%), the “Socially Vulnerable” (26.8%), and the “Insecure Bi-Strategic” (4.8%). These profiles did not significantly vary regarding their Internet usage and interpersonal sensitivity behaviours. Interestingly, lower self-perceived popularity predicted higher interpersonal sensitivity, whereas higher actual popularity predicted excessive Internet use. Findings have important implications for student-tailored mental health prevention and intervention practices. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Purpose\ud To develop and assess a method for acquiring coregistered proton anatomical and hyperpolarized 129Xe ventilation MR images of the lungs with compressed sensing (CS) in a single breath hold.\ud \ud Methods\ud Retrospective CS simulations were performed on fully sampled ventilation images acquired from one healthy smoker to optimize reconstruction parameters. Prospective same‐breath anatomical and ventilation images were also acquired in five ex‐smokers with an acceleration factor of 3 for hyperpolarized 129Xe images, and were compared to fully sampled images acquired during the same session. The following metrics were used to assess data fidelity: mean absolute error (MAE), root mean square error, and linear regression of the signal intensity between fully sampled and undersampled images. The effect of CS reconstruction on two quantitative imaging metrics routinely reported [percentage ventilated volume (%VV) and heterogeneity score] was also investigated.\ud \ud Results\ud Retrospective simulations showed good agreement between fully sampled and CS‐reconstructed (acceleration factor of 3) images with MAE (root mean square error) of 3.9% (4.5%). The prospective same‐breath images showed a good match in ventilation distribution with an average R2 of 0.76 from signal intensity linear regression and a negligible systematic bias of +0.1% in %VV calculation. A bias of −1.8% in the heterogeneity score was obtained.\ud \ud Conclusion\ud With CS, high‐quality 3D images of hyperpolarized 129Xe ventilation (resolution 4.2 × 4.2 × 7.5 mm3) can be acquired with coregistered 1H anatomical MRI in a 15‐s breath hold. The accelerated acquisition time dispenses with the need for registration between separate breath‐hold 129Xe and 1H MRI, enabling more accurate %VV calculation.

Prognosticating idiopathic pulmonary fibrosis (IPF) is challenging, in part due to a lack of sensitive biomarkers. A recent article in Thorax described how hyperpolarised xenon magnetic resonance spectroscopy may quantify regional gas exchange in IPF lungs. In a population of patients with IPF, we find that the xenon signal from red blood cells diminishes relative to the tissue/plasma signal over a 12-month time period, even when the diffusion factor for carbon monoxide is static over the same time period. We conclude that hyperpolarised 129Xe MR spectroscopy may be sensitive to short-term changes in interstitial gas diffusion in IPF.

Background\ud MRI with inhaled hyperpolarized helium 3 (3He) allows for functional and structural imaging of the lungs. Hyperpolarized gas diffusion-weighted (DW) MRI provides noninvasive and quantitative assessment of microstructural acinar changes in the lungs.\ud \ud Purpose\ud To investigate whether microstructural imaging metrics from in-vivo hyperpolarized 3He DW MRI are sensitive to longitudinal changes in a cohort of participants with idiopathic pulmonary fibrosis (IPF) and to evaluate the reproducibility of these metrics and their correlation with existing clinical measures of IPF disease severity.\ud \ud Materials and Methods\ud In this prospective study, 18 participants with IPF underwent 3He DW MRI at 1.5 T and 11 participants underwent an identical same-day examination for reproducibility assessment. Thirteen participants returned for 6- and 12-month follow-up examinations. Pulmonary function tests, including diffusing capacity of the lungs for carbon monoxide and forced vital capacity, were performed at each examination. The apparent diffusion coefficient (ADC) and stretched exponential model–derived mean diffusive length scale (LmD) from DW MRI was compared with baseline CT fibrosis scores and pulmonary function tests by using Spearman rank correlation coefficient. Longitudinal changes in DW MRI and pulmonary function test measurements were assessed with Friedman tests and post hoc Dunn test.\ud \ud Results\ud 3He ADC and LmD were reproducible (mean Bland-Altman analysis bias, 0.002 cm2 · sec-1 and −1.5 μm, respectively). Elevated ADC and LmD regions qualitatively corresponded to fibrotic regions at CT. ADC and LmD correlated with diffusing capacity of the lungs for carbon monoxide (respectively: r = −0.56, P = .017; and r = −0.54, P = .02) and CT fibrosis score (respectively: r = 0.71, P = .001; and r = 0.65, P = .003). LmD increased by 12 μm after 12 months (P = .001) whereas mean ADC (P = .17), forced vital capacity (P = .12), and diffusing capacity of the lungs for carbon monoxide (P > .99) were not statistically different between examinations.\ud \ud Conclusion\ud Helium 3 diffusion-weighted MRI-derived mean diffusive length scale demonstrates longitudinal changes in lungs affected by idiopathic pulmonary fibrosis.

Image registration of lung CT images acquired at different inflation levels has been proposed as a surrogate method to map lung 'ventilation'. Prior to clinical use, it is important to understand how this technique compares with direct ventilation imaging modalities such as hyperpolarised gas MRI. However, variations in lung inflation level have been shown to affect regional ventilation distributions. Therefore, the aim of this study was to evaluate the impact of lung inflation levels when comparing CT ventilation imaging to ventilation from 3He-MRI. 7 asthma patients underwent breath-hold CT at total lung capacity (TLC) and functional residual capacity (FRC). 3He-MRI and a same-breath 1H-MRI were acquired at FRC+1L and TLC. Percentage ventilated volumes (%VVs) were calculated for FRC+1L and TLC 3He-MRI. TLC-CT and registered FRC-CT were used to compute a surrogate ventilation map from voxel-wise intensity differences in Hounsfield unit values, which was thresholded at the 10th and 20th percentiles. For direct comparison of CT and 3He-MRI ventilation, FRC+1L and TLC 3He-MRI were registered to TLC-CT indirectly via the corresponding same-breath 1H-MRI data. For 3He-MRI and CT ventilation comparison, Dice similarity coefficients (DSCs) between the binary segmentations were computed. The median (range) of %VVs for FRC+1L and TLC 3He-MRI were 90.5 (54.9-93.6) and 91.8 (67.8-96.2), respectively (p=0.018). For MRI versus CT ventilation comparison, statistically significant improvements in DSCs were observed for TLC 3He MRI when compared with FRC+1L, with median (range) values of 0.93 (0.86-0.93) and 0.86 (0.68-0.92), respectively (p=0.017), for the 10-100th percentile and 0.87 (0.83-0.88) and 0.81 (0.66-0.87), respectively (p=0.027), for the 20-100th percentile. Correlation of CT ventilation imaging and hyperpolarised gas MRI is sensitive to lung inflation level. For ventilation maps derived from CT acquired at FRC and TLC, a higher correlation with gas ventilation MRI can be achieved if the MRI is acquired at TLC. &#13.

Purpose\ud To compare in vivo lung morphometry parameters derived from theoretical gas diffusion models, the cylinder model and stretched exponential model, in a range of acinar microstructural length scales encountered in healthy and diseased lungs with 3He and 129Xe diffusion‐weighted MRI.\ud \ud Methods\ud Three‐dimensional multiple b‐value 3He and 129Xe diffusion‐weighted MRI was acquired with compressed sensing at 1.5 T from 51 and 31 subjects, respectively, including healthy volunteers, ex‐smokers, idiopathic pulmonary fibrosis, and chronic obstructive pulmonary disease patients. For each subject, the stretched exponential model–derived mean diffusive length scale (LmD) was calculated from the diffusion signal decay, and was compared with the cylinder model–derived mean chord length (Lm) and mean alveolar diameter (LAlv) in order to determine the relationships among the different lung morphometry parameters.\ud \ud Results\ud For both 3He and 129Xe diffusion‐weighted MRI, the mean global LmD value was significantly related (P < .001) to Lm in a nonlinear power relationship, whereas the LAlv demonstrated excellent linear correlation (P < .001) with LmD. A mean bias of +1.0% and urn:x-wiley:07403194:media:mrm27608:mrm27608-math-00012.6% toward LmD was obtained for Bland‐Altman analyses of 3He and 129Xe LmD and LAlv values, suggesting that the two morphometric parameters are equivalent measures of mean acinar dimensions.\ud \ud Conclusion\ud Within the experimental range of parameters considered here for both 3He and 129Xe, the stretched exponential model–derived LmD is related nonlinearly to cylinder model–derived Lm, and demonstrates excellent agreement with the cylinder model–derived LAlv.

Here we present a Rb−129Xe spin-exchange optical pumping polarizer capable of rapid generation of large volumes of highly polarized 129Xe gas. Through modeling and measurements we maximize the 129Xe nuclear spin polarization output to enable the generation of polarized 129Xe gas imaging volumes (300 cm3) every 5 min within a clinical setting. Our model is verified by experiment to correctly predict the optimum Rb vapor density for maximum 129Xe nuclear polarization for a flux 3.4 W/cm2 of circularly polarized Rb D1 photons incident on an 80 cm long cylindrical optical cell. We measure a 129Xe magnetization production efficiency of ηpr=1.8%, which approaches the photon efficiency limit ηγ=3.3% of this system and enables the polarization of 2.72×1022 129Xe spins per hour, corresponding to 1013 cm3 of 100% polarized 129Xe at STP. This magnetization production rate is threefold higher than the highest previously published 129Xe magnetization production rate and has enabled routine clinical lung magnetic resonance imaging (MRI) with hyperpolarized 129Xe doses available on demand at run time, as well as high-SNR 129Xe MRI of the human brain and kidneys.