Imaging Collateral Ventilation in Patients With Advanced Chronic Obstructive Pulmonary Disease: Relative Sensitivity of 3 He and 129 Xe MRI.
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SUBMITTER: Marshall H
PROVIDER: S-EPMC6749943 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:PurposeHyperpolarized 129 Xe MRI characterizes regional lung ventilation in a variety of disease populations, with high sensitivity to airway obstruction in early disease. However, ventilation images are usually limited to a single breath-hold and most-often acquired using gradient-recalled echo sequences with thick slices (~10-15 mm), which increases partial-volume effects, limits ability to observe small defects, and suffers from imperfect slice selection. We demonstrate higher-resolution ventilation images, in shorter breath-holds, using FLORET (Fermat Looped ORthogonally Encoded Trajectories), a center-out 3D-spiral UTE sequence.MethodsIn vivo human adult (N = 4; 2 healthy, 2 with cystic fibrosis) 129 Xe images were acquired using 2D gradient-recalled echo, 3D radial, and FLORET. Each sequence was acquired at its highest possible resolution within a 16-second breath-hold with a minimum voxel dimension of 3 mm. Images were compared using 129 Xe ventilation defect percentage, SNR, similarity coefficients, and vasculature cross-sections.ResultsThe FLORET sequence obtained relative normalized SNR, 40% greater than 2D gradient-recalled echo (P = .012) and 26% greater than 3D radial (P = .067). Moreover, the FLORET images were acquired with 3-fold-higher nominal resolution in a 15% shorter breath-hold. Finally, vasculature was less prominent in FLORET, likely due to diminished susceptibility-induced dephasing at shorter TEs afforded by UTE sequences.ConclusionThe FLORET sequence yields higher SNR for a given resolution with a shorter breath-hold than traditional ventilation imaging techniques. This sequence more accurately measures ventilation abnormalities and enables reduced scan times in patients with poor compliance and severe lung disease.
| S-EPMC7083696 | biostudies-literature
Project description:PurposeTo develop and optimize a rapid dynamic hyperpolarized 129 Xe ventilation (DXeV) MRI protocol and investigate the feasibility of capturing pulmonary signal-time curves in human lungs.Theory and methodsSpiral k-space trajectories were designed with the number of interleaves Nint = 1, 2, 4, and 8 corresponding to voxel sizes of 8 mm, 5 mm, 4 mm, and 2.5 mm, respectively, for field of view = 15 cm. DXeV images were acquired from a gas-flow phantom to investigate the ability of Nint = 1, 2, 4, and 8 to capture signal-time curves. A finite element model was constructed to investigate gas-flow dynamics corroborating the experimental signal-time curves. DXeV images were also carried out in six subjects (three healthy and three chronic obstructive pulmonary disease subjects).ResultsDXeV images and numerical modelling of signal-time curves permitted the quantification of temporal and spatial resolutions for different numbers of spiral interleaves. The two-interleaved spiral (Nint = 2) was found to be the most time-efficient to obtain DXeV images and signal-time curves of whole lungs with a temporal resolution of 624 ms for 13 slices. Signal-time curves were well matched in three healthy volunteers. The Spearman's correlations of chronic obstructive pulmonary disease subjects were statistically different from three healthy subjects (P < 0.05).ConclusionThe Nint = 2 spiral demonstrates the successful acquisition of DXeV images and signal-time curves in healthy subjects and chronic obstructive pulmonary disease patients. Magn Reson Med 79:2597-2606, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
| S-EPMC5836876 | biostudies-literature
Project description:Background In individuals with postacute COVID-19 syndrome (PACS) and normal pulmonary function, xenon 129 (129Xe) MRI ventilation defects, abnormal quality-of-life scores, and exercise limitation were reported 3 months after infection; the longitudinal trajectory remains unclear. Purpose To measure and compare pulmonary function, exercise capacity, quality of life, and 129Xe MRI ventilation defect percent (VDP) in individuals with PACS evaluated 3 and 15 months after COVID-19 infection. Materials and Methods In this prospective study, participants with PACS aged 18-80 years were enrolled between July 2020 and August 2021 from two quaternary care centers. 129Xe MRI VDP, diffusing capacity of lung for carbon monoxide (Dlco), spirometry, oscillometry, 6-minute walk distance (6MWD), and St George Respiratory Questionnaire (SGRQ) scores were evaluated 3 months and 15 months after COVID-19 infection. Differences between time points were evaluated using the paired t test. Multivariable models were generated to explain exercise capacity and quality-of-life improvement. Odds ratios (ORs) were used to evaluate potential treatment influences. Results Overall, 53 participants (mean age, 55 years ± 18 [SD]; 27 women) attended both 3- and 15-month visits and were included in the analysis. The mean values for 129Xe MRI VDP (5.8% and 4.2%; P = .003), forced expiratory volume in the 1st second of expiration percent predicted (84% and 90%; P = .001), Dlco percent predicted (86% and 99%; P = .002), and SGRQ score (35 and 25; P < .001) improved between the 3- and 15-month visit. VDP measured 3 months after COVID-19 infection predicted the change in 6MWD (β = -0.643, P = .006), while treatment with respiratory medication at 3 months predicted an improved quality-of-life score at 15 months (OR, 4.0; 95% CI: 1.2, 13.8; P = .03). Conclusion Pulmonary function, gas exchange, exercise capacity, quality of life, and 129Xe MRI ventilation defect percent (VDP) improved in participants with postacute COVID-19 syndrome at 15 months compared with 3 months after infection. VDP measured at 3 months after infection correlated with improved exercise capacity, while treatment with respiratory medication was associated with an improved quality-of-life score 15 months after infection. ClinicalTrials.gov registration no. NCT05014516 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Vogel-Claussen in this issue.
| S-EPMC9926501 | biostudies-literature
Project description:BackgroundPatients often report persistent symptoms beyond the acute infectious phase of COVID-19. Hyperpolarised 129Xe MRI provides a way to directly measure airway functional abnormalities; the clinical relevance of 129Xe MRI ventilation defects in ever-hospitalised and never-hospitalised patients who had COVID-19 has not been ascertained. It remains unclear if persistent symptoms beyond the infectious phase are related to small airways disease and ventilation heterogeneity. Hence, we measured 129Xe MRI ventilation defects, pulmonary function and symptoms in ever-hospitalised and never-hospitalised patients who had COVID-19 with persistent symptoms consistent with post-acute COVID-19 syndrome (PACS).MethodsConsenting participants with a confirmed diagnosis of PACS completed 129Xe MRI, CT, spirometry, multi-breath inert-gas washout, 6-minute walk test, St. George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnoea scale, modified Borg scale and International Physical Activity Questionnaire. Consenting ever-COVID volunteers completed 129Xe MRI and pulmonary function tests only.ResultsSeventy-six post-COVID and nine never-COVID participants were evaluated. Ventilation defect per cent (VDP) was abnormal and significantly greater in ever-COVID as compared with never-COVID participants (p<0.001) and significantly greater in ever-hospitalised compared with never-hospitalised participants who had COVID-19 (p=0.048), in whom diffusing capacity of the lung for carbon-monoxide (p=0.009) and 6-minute walk distance (6MWD) (p=0.005) were also significantly different. 129Xe MRI VDP was also related to the 6MWD (p=0.02) and post-exertional SpO2 (p=0.002). Participants with abnormal VDP (≥4.3%) had significantly worse 6MWD (p=0.003) and post-exertional SpO2 (p=0.03).Conclusion129Xe MRI VDP was significantly worse in ever-hospitalised as compared with never-hospitalised participants and was related to 6MWD and exertional SpO2 but not SGRQ or mMRC scores.Trial registration numberNCT05014516.
| S-EPMC9119175 | biostudies-literature
Project description:Fast apparent transverse relaxation (short T2 *) is a common obstacle when attempting to perform quantitative 1 H MRI of the lungs. While T2 * times are longer for pulmonary hyperpolarized (HP) gas functional imaging (in particular for gaseous 129 Xe), T2 * 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. However, the T2 * of HP 129 Xe in the most common animal model of human disease (mice) has not been reported. Herein, we present a multi-echo radial flyback imaging sequence and use it to measure HP 129 Xe T2 * at 7 T under a variety of respiratory conditions. This sequence mitigates the impact of T1 relaxation outside the animal by using multiple gradient-refocused echoes to acquire images at a number of effective echo times for each RF excitation. After validating the sequence using a phantom containing water doped with superparamagnetic iron oxide nanoparticles, we measured the 129 Xe T2 * in vivo for 10 healthy C57Bl/6 J mice and found T2 * ~ 5 ms in the lung airspaces. Interestingly, T2 * was relatively constant over all experimental conditions, and varied significantly with sex, but not age, mass, or the O2 content of the inhaled gas mixture. These results are discussed in the context of T2 * relaxation within porous media.
| S-EPMC7702724 | biostudies-literature
Project description:Magnetic resonance (MR) imaging and spectroscopy using dissolved hyperpolarized (HP) 129Xe have expanded the ability to probe lung function regionally and noninvasively. In particular, HP 129Xe imaging has been used to quantify impaired gas uptake by the pulmonary tissues. Whole-lung spectroscopy has also been used to assess global cardiogenic oscillations in the MR signal intensity originating from 129Xe dissolved in the red blood cells of pulmonary capillaries. Herein, we show that the magnitude of these cardiogenic dynamics can be mapped three dimensionally using radial MRI, because dissolved 129Xe dynamics are encoded directly in the raw imaging data. Specifically, 1-point Dixon imaging is combined with postacquisition keyhole image reconstruction to assess regional blood volume fluctuations within the pulmonary microvasculature throughout the cardiac cycle. This "oscillation mapping" was applied in healthy subjects (mean amplitude 9% of total RBC signal) and patients with pulmonary arterial hypertension (PAH; mean 4%) and idiopathic pulmonary fibrosis (IPF; mean 14%). Whole-lung mean values from these oscillation maps correlated strongly with spectroscopy and clinical pulmonary function testing, but exhibited significant regional heterogeneity, including gravitationally dependent gradients in healthy subjects. Moreover, regional oscillations were found to be sensitive to disease state. Greater percentages of the lungs exhibit low-amplitude oscillations in PAH patients, and longitudinal imaging shows high-amplitude oscillations increase significantly over time (4-14 mo, P = 0.02) in IPF patients. This technique enables regional dynamics within the pulmonary capillary bed to be measured, and in doing so, provides insight into the origin and progression of pathophysiology within the lung microvasculature.NEW & NOTEWORTHY Spatially heterogeneous abnormalities within the lung microvasculature contribute to pathology in various cardiopulmonary diseases but are difficult to assess noninvasively. Hyperpolarized 129Xe MRI is a noninvasive method to probe lung function, including regional gas exchange between pulmonary air spaces and capillaries. We show that cardiogenic oscillations in the raw dissolved 129Xe MRI signal from pulmonary capillary red blood cells can be imaged using a postacquisition reconstruction technique, providing a new means of assessing regional lung microvasculature function and disease state.
| S-EPMC7473944 | biostudies-literature
Project description:Cryptophane-based biosensors are promising agents for the ultrasensitive detection of biomedically relevant targets via 129Xe NMR. Dynamic light scattering revealed that cryptophanes form water-soluble aggregates tens to hundreds of nanometers in size. Acridine orange fluorescence quenching assays allowed quantitation of the aggregation state, with critical concentrations ranging from 200 nM to 600 nM, depending on the cryptophane species in solution. The addition of excess carbonic anhydrase (CA) protein target to a benzenesulfonamide-functionalized cryptophane biosensor (C8B) led to C8B disaggregation and produced the expected 1:1 C8B-CA complex. C8B showed higher affinity at 298 K for the cytoplasmic isozyme CAII than the extracellular CAXII isozyme, which is a biomarker of cancer. Using hyper-CEST NMR, we explored the role of stoichiometry in detecting these two isozymes. Under CA-saturating conditions, we observed that isozyme CAII produces a larger 129Xe NMR chemical shift change (δ = 5.9 ppm, relative to free biosensor) than CAXII (δ = 2.7 ppm), which indicates the strong potential for isozyme-specific detection. However, stoichiometry-dependent chemical shift data indicated that biosensor disaggregation contributes to the observed 129Xe NMR chemical shift change that is normally assigned to biosensor-target binding. Finally, we determined that monomeric cryptophane solutions improve hyper-CEST saturation contrast, which enables ultrasensitive detection of biosensor-protein complexes. These insights into cryptophane-solution behavior support further development of xenon biosensors, but will require reinterpretation of the data previously obtained for many water-soluble cryptophanes.
| S-EPMC6050516 | biostudies-literature
Project description:The recovery process of COVID-19 patients is unclear. Some recovered patients complain of continued shortness of breath. Vasculopathy has been reported in COVID-19, stressing the importance of probing microstructure and function of lungs at the alveolar-capillary interface. While CT detects structural abnormalities, little is known about the impact of disease on lung function. 129Xe MRI is a technique uniquely capable of assessing ventilation, microstructure and gas exchange. Using 129Xe MRI, we found COVID-19 patients have higher ventilation defects percentage (5.9% vs 3.7%), unchanged microstructure, longer gas-blood exchange time (43.5 ms vs 32.5 ms), and reduced RBC/TP (0.279 vs 0.330) compared with healthy subjects. These findings suggest regional ventilation and alveolar airspace dimensions are relatively normal around the time of discharge, while gas-blood exchange function is diminished. This study establishes the feasibility of localized lung function measurement in COVID-19 patients. Such readouts could be useful as a supplement to structural imaging.
| S-EPMC7775756 | biostudies-literature
Project description:A decacationic water-soluble pillar[5]arene possessing a nonsolvated hydrophobic core has been designed and synthesized. This supramolecular host is capable of binding xenon, as evidenced by hyperCEST depletion experiments. Fluorescence-based studies also demonstrate that xenon binds into the cavity of the pillararene with an association constant of 4.6 × 103 M-1. These data indicate that the water-soluble pillararene is a potential scaffold for building contrast agents that can be detected by xenon-129 magnetic resonance imaging.
| S-EPMC7643082 | biostudies-literature
Project description:Gas vesicle nanoparticles (GVs) are gas-containing protein assemblies expressed in bacteria and archaea. Recently, GVs have gained considerable attention for biotechnological applications as genetically encodable contrast agents for MRI and ultrasonography. However, at present, the practical use of GVs is hampered by a lack of robust methodology for their induction into mammalian cells. Here, we demonstrate the genetic reconstitution of protein nanoparticles with characteristic bicone structures similar to natural GVs in a human breast cancer cell line KPL-4 and genetic control of their size and shape through expression of reduced sets of humanized gas vesicle genes cloned into Tol2 transposon vectors, referencing the natural gas vesicle gene clusters of the cyanobacteria planktothrix rubescens/agardhii. We then report the utility of these nanoparticles as multiplexed, sensitive, and genetically encoded contrast agents for hyperpolarized xenon chemical exchange saturation transfer (HyperCEST) MRI.
| S-EPMC7091528 | biostudies-literature