Dynamic evaluation of acute lung injury using hyperpolarized Xe magnetic resonance.

Prognosticating acute lung injury (ALI) is challenging, in part because of a lack of sensitive biomarkers. Hyperpolarized gas magnetic resonance (MR) has unique advantages in pulmonary function measurement and can provide promising biomarkers for the assessment of lung injuries. Herein, we employ hyperpolarized Xe MRI and generate a number of imaging biomarkers to detect the pulmonary physiological and morphological changes during the progression of ALI in an animal model.

Improvement in the signal amplitude and bandwidth of an optical atomic magnetometer via alignment-to-orientation conversion.

We evaluated the alignment-to-orientation conversion (AOC) at the cesium D1 line to improve a nonlinear magneto-optical rotation (NMOR) optical atomic magnetometer's signal amplitude and bandwidth. For the 6 S F = 3 → 6 P F' = 4 transition, the AOC-related NMOR achieves a 1.7-fold enhancement in signal amplitude compared to the conventional NMOR, benefiting from narrow linewidth and ultraweak power broadening.

Accelerate gas diffusion-weighted MRI for lung morphometry with deep learning.

Objectives: Multiple b-value gas diffusion-weighted MRI (DW-MRI) enables non-invasive and quantitative assessment of lung morphometry, but its long acquisition time is not well-tolerated by patients. We aimed to accelerate multiple b-value gas DW-MRI for lung morphometry using deep learning.

Methods: A deep cascade of residual dense network (DC-RDN) was developed to reconstruct high-quality DW images from highly undersampled k-space data.

Quieting an environmental magnetic field without shielding.

We construct an active magnetic compensation device and propose an efficient magnetic compensation method that suppresses a wider range of frequencies and amplitudes of time-varying magnetic fields than conventional methods. This system can compensate for all frequencies in the bandwidth of the sensors used by analyzing and extracting the spectral characteristics of the ambient field. We compensate simultaneously for various types of interference in rotation and achieve a reduction of the 50-Hz power-frequency field noise by 36 dB.

Quantitative evaluation of lung injury caused by PM using hyperpolarized gas magnetic resonance.

Purpose: To demonstrate the feasibility of Xe MR in evaluating the pulmonary physiological changes caused by PM in animal models.

Methods: Six rats were treated with PM solution (16.2 mg/kg) by intratracheal instillation twice a week for 4 weeks, and another six rats treated with normal saline served as the control cohort.

Fast and accurate reconstruction of human lung gas MRI with deep learning.

Purpose: To fast and accurately reconstruct human lung gas MRI from highly undersampled k-space using deep learning.

Methods: The scheme was comprised of coarse-to-fine nets (C-net and F-net). Zero-filling images from retrospectively undersampled k-space at an acceleration factor of 4 were used as input for C-net, and then output intermediate results which were fed into F-net.

Single breath-hold measurement of pulmonary gas exchange and diffusion in humans with hyperpolarized Xe MR.

Pulmonary diseases usually result in changes of the blood-gas exchange function in the early stages. Gas exchange across the respiratory membrane and gas diffusion in the alveoli can be quantified using hyperpolarized Xe MR via chemical shift saturation recovery (CSSR) and diffusion-weighted imaging (DWI), respectively. Generally, CSSR and DWI data have been collected in separate breaths in humans.

Highly and Adaptively Undersampling Pattern for Pulmonary Hyperpolarized Xe Dynamic MRI.

Hyperpolarized (HP) gas (e.g., He or Xe) dynamic MRI could visualize the lung ventilation process, which provides characteristics regarding lung physiology and pathophysiology.

Quantitative evaluation of pulmonary gas-exchange function using hyperpolarized Xe CEST MRS and MRI.

Hyperpolarized Xe gas MR has been a powerful tool for evaluating pulmonary structure and function due to the extremely high enhancement in spin polarization, the good solubility in the pulmonary parenchyma, and the excellent chemical sensitivity to its surrounding environment. Generally, the quantitative structural and functional information of the lung are evaluated using hyperpolarized Xe by employing the techniques of chemical shift saturation recovery (CSSR) and xenon polarization transfer contrast (XTC). Hyperpolarized Xe chemical exchange saturation transfer (Hyper-CEST) is another method for quantifying the exchange information of hyperpolarized Xe by using the exchange of xenon signals according to its different chemical shifts, and it has been widely used in biosensor studies in vitro.

A Multiscale Fuzzy Metric for Detecting Small Infrared Targets Against Chaotic Cloudy/Sea-Sky Backgrounds.

In a low signal-to-clutter ratio (SCR) small-infrared-target image with chaotic cloudy-/sea-sky background, the target has very similar thermal intensities to the background (e.g., edges of clouds).

Lung morphometry using hyperpolarized Xe multi-b diffusion MRI with compressed sensing in healthy subjects and patients with COPD.

Purpose: To demonstrate the feasibility of compressed sensing (CS) to accelerate the acquisition of hyperpolarized (HP) Xe multi-b diffusion MRI for quantitative assessments of lung microstructural morphometry.

Methods: Six healthy subjects and six chronic obstructive pulmonary disease (COPD) subjects underwent HP Xe multi-b diffusion MRI (b = 0, 10, 20, 30, and 40 s/cm ). First, a fully sampled (FS) acquisition of HP Xe multi-b diffusion MRI was conducted in one healthy subject.

Considering low-rank, sparse and gas-inflow effects constraints for accelerated pulmonary dynamic hyperpolarized Xe MRI.

Dynamic hyperpolarized (HP) Xe MRI is able to visualize the process of lung ventilation, which potentially provides unique information about lung physiology and pathophysiology. However, the longitudinal magnetization of HP Xe is nonrenewable, making it difficult to achieve high image quality while maintaining high temporal-spatial resolution in the pulmonary dynamic MRI. In this paper, we propose a new accelerated dynamic HP Xe MRI scheme incorporating the low-rank, sparse and gas-inflow effects (L + S + G) constraints.

Simultaneous assessment of both lung morphometry and gas exchange function within a single breath-hold by hyperpolarized Xe MRI.

During the measurement of hyperpolarized Xe magnetic resonance imaging (MRI), the diffusion-weighted imaging (DWI) technique provides valuable information for the assessment of lung morphometry at the alveolar level, whereas the chemical shift saturation recovery (CSSR) technique can evaluate the gas exchange function of the lungs. To date, the two techniques have only been performed during separate breaths. However, the request for multiple breaths increases the cost and scanning time, limiting clinical application.

Detection of smoke-induced pulmonary lesions by hyperpolarized Xe diffusion kurtosis imaging in rat models.

Purpose: To demonstrate that hyperpolarized (HP) xenon diffusion kurtosis imaging (DKI) is able to detect smoke-induced pulmonary lesions in rat models.

Methods: Multi-b DKI with hyperpolarized xenon was used for the first time in five smoke-exposed rats and five healthy rats. Additionally, DKI with b values of up to 80 s/cm were used in two healthy rats to probe the critical b value (a limit beyond which the DKI cannot describe the non-Gaussian diffusion).

Mammogram Enhancement Using Intuitionistic Fuzzy Sets.

Objective: Conventional mammogram enhancement methods use transform-domain filtering, which possibly produce some artifacts or not well highlight all local details in images. This paper presents a new enhancement method based on intuitionistic fuzzy sets.

Methods: The presented algorithm initially separates a mammogram via a global threshold and then fuzzifies the image utilizing the intuitionistic fuzzy membership function that adopts restricted equivalence functions.

Adaptive Intuitionistic Fuzzy Enhancement of Brain Tumor MR Images.

Image enhancement techniques are able to improve the contrast and visual quality of magnetic resonance (MR) images. However, conventional methods cannot make up some deficiencies encountered by respective brain tumor MR imaging modes. In this paper, we propose an adaptive intuitionistic fuzzy sets-based scheme, called as AIFE, which takes information provided from different MR acquisitions and tries to enhance the normal and abnormal structural regions of the brain while displaying the enhanced results as a single image.

Detection of the mild emphysema by quantification of lung respiratory airways with hyperpolarized xenon diffusion MRI.

Purpose: To demonstrate the feasibility to quantify the lung respiratory airway in vivo with hyperpolarized xenon diffusion magnetic resonance imaging (MRI), which is able to detect mild emphysema in the rat model.

Materials And Methods: The lung respiratory airways were quantified in vivo using hyperpolarized xenon diffusion MRI (7T) with eight b values (5, 10, 15, 20, 25, 30, 35, 40 s/cm ) in five control rats and five mild emphysematous rats, which were induced by elastase. The morphological results from histology were acquired and used for comparison.

Fast Determination of Flip Angle and T1 in Hyperpolarized Gas MRI During a Single Breath-Hold.

MRI of hyperpolarized media, such as (129)Xe and (3)He, shows great potential for clinical applications. The optimal use of the available spin polarization requires accurate flip angle calibrations and T1 measurements. Traditional flip angle calibration methods are time-consuming and suffer from polarization losses during T1 relaxation.

Oxygen-dependent hyperpolarized (129) Xe brain MR.

Hyperpolarized (HP) (129) Xe MR offers unique advantages for brain functional imaging (fMRI) because of its extremely high sensitivity to different chemical environments and the total absence of background noise in biological tissues. However, its advancement and applications are currently plagued by issues of signal strength. Generally, xenon atoms found in the brain after inhalation are transferred from the lung via the bloodstream.

Constant-variable flip angles for hyperpolarized media MRI.

The longitudinal magnetization of hyperpolarized media, such as hyperpolarized (129)Xe, (3)He, etc., is nonrenewable. When the MRI data acquisition begins at the k-domain center, a constant flip angle (CFA) results in an image of high signal-to-noise ratio (SNR) but sacrifices the accuracy of spatial information.

Quantitative evaluation of radiation-induced lung injury with hyperpolarized xenon magnetic resonance.

Purpose: To demonstrate the feasibility of quantitative and comprehensive global evaluation of pulmonary function and microstructural changes in rats with radiation-induced lung injury (RILI) using hyperpolarized xenon MR.

Methods: Dissolved xenon spectra were dynamically acquired using a modified chemical shift saturation recovery pulse sequence in five rats with RILI (bilaterally exposed by 6-MV x-ray with a dose of 14 Gy 3 mo. prior to MR experiments) and five healthy rats.

Atomic filter based on stimulated Raman transition at the rubidium D1 line.

We report on a 795 nm atomic filter consisting of a stimulated Raman gain amplifier together with normal Faraday anomalous dispersion optical filtering (FADOF) at the rubidium D1 line. The filter is operated with a single transmission peak. The gain of the filter's transmission light signal is enhanced up to 85-fold compared to case operating without a stimulated Raman transition.

Ultralow field NMR spectrometer with an atomic magnetometer near room temperature.

We present a Cs atomic magnetometer with a sensitivity of 150fT/Hz(1/2) operating near room temperature. The nuclear magnetic resonance (NMR) signal of 125μL tap water was detected at an ultralow magnetic field down to 47nT, with the signal-to-noise ratio (SNR) of the NMR signal approaching 50 after eight averages. Relaxivity experiments with a Gd(DTPA) contrast agent in zero field were performed, in order to show the magnetometer's ability to measure spin-lattice relaxation time with high accuracy.

Quantitative estimation of SPINOE enhancement in solid state.

A theoretical approach to quantitatively estimate the spin polarization enhancement via spin polarization-induced nuclear Overhauser effect (SPINOE) in solid state is presented. We show that theoretical estimates from the model are in good agreement with published experimental results. This method provides a straightforward way to predict the enhanced factor of nuclear magnetic resonance signals in solid state experiments.