High-quality FLORET UTE imaging for clinical translation.

Purpose: To develop a robust 3D ultrashort-TE (UTE) protocol that can reproducibly provide high-quality images, assessed by the ability to yield clinically diagnostic images, and is suitable for clinical translation.

Theory And Methods: Building on previous work, a UTE sampled with Fermat looped orthogonally encoded trajectories (FLORET) was chosen as a starting point due to its shorter, clinically reasonable scan times. Modifications to previous FLORET implementations included gradient waveform frequency limitations, a new trajectory ordering scheme, a balanced SSFP implementation, fast gradient spoiling, and full inline reconstruction.

Simultaneous brain and neck time-of-flight MRA using spiral multiband with localized quadratic encoding.

Purpose: To develop a method that achieves simultaneous brain and neck time-of-flight (ToF) magnetic resonance angiography (MRA) within feasible scan timeframes.

Methods: Localized quadratic (LQ) encoding is efficient for both signal-to-noise ratio (SNR) and in-flow enhancement. We proposed a spiral multiband LQ method to enable simultaneous intracranial and carotid ToF-MRA within a single scan.

Spiral inflow MRA with sliding-slice localized quadratic encoding.

Purpose: This work proposes a 2D/3D hybrid inflow MRA technique for fast scanning and high SNR and contrast-to-noise (CNR) efficiencies.

Methods: Localized quadratic (LQ) encoding was combined with a sliding-slice spiral acquisition. Inflow MRAs around the circle of Willis and the carotid bifurcations were collected on four healthy volunteers.

A field map updating algorithm to improve fat-water spiral imaging.

Purpose: An accurate field map is essential to separate fat and water signals in a dual-echo chemical shift encoded spiral MRI scan. A rapid low-resolution B map prescan is usually performed before each exam. Occasional inaccuracy in these field map estimates can lead to misclassification of the water and fat signals as well as blurring artifacts in the reconstruction.

4D lung MRI with high-isotropic-resolution using half-spoke (UTE) and full-spoke 3D radial acquisition and temporal compressed sensing reconstruction.

. To develop a respiratory motion-resolved four-dimensional (4D) magnetic resonance imaging (MRI) technique with high-isotropic-resolution (1.1 mm) using 3D radial sampling, camera-based respiratory motion sensing, and temporal compressed sensing reconstruction for lung cancer imaging.

Free-breathing 2D radial cine MRI with respiratory auto-calibrated motion correction (RAMCO).

Purpose: To develop a free-breathing (FB) 2D radial balanced steady-state free precession cine cardiac MRI method with 100% respiratory gating efficiency using respiratory auto-calibrated motion correction (RAMCO) based on a motion-sensing camera.

Methods: The signal from a respiratory motion-sensing camera was recorded during a FB retrospectively electrocardiogram triggered 2D radial balanced steady-state free precession acquisition using pseudo-tiny-golden-angle ordering. With RAMCO, for each acquisition the respiratory signal was retrospectively auto-calibrated by applying different linear translations, using the resulting in-plane image sharpness as a criterium.

Human upper-airway respiratory airflow: In vivo comparison of computational fluid dynamics simulations and hyperpolarized 129Xe phase contrast MRI velocimetry.

Computational 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.

Variable anisotropic FOV for 3D radial imaging with spiral phyllotaxis (VASP).

Purpose: To develop a new 3D radial trajectory based on the natural spiral phyllotaxis (SP), with variable anisotropic FOV.

Theory & Methods: A 3D radial trajectory based on the SP with favorable interleaving properties for cardiac imaging has been proposed by Piccini et al (Magn Reson Med. 2011;66:1049-1056), which supports a FOV with a fixed anisotropy.

Longitudinal imaging reveals subhippocampal dynamics in glutamate levels associated with histopathologic events in a mouse model of tauopathy and healthy mice.

Tauopathies are neurodegenerative disorders characterized by abnormal intracellular aggregates of tau protein, and include Alzheimer's disease, corticobasal degeneration, frontotemporal dementia, and traumatic brain injury. Glutamate metabolism is altered in neurodegenerative disorders manifesting in higher or lower concentrations of glutamate, its transporters or receptors. Previously, glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging (MRI) demonstrated that glutamate levels are reduced in regions of synapse loss in the hippocampus of a mouse model of late-stage tauopathy.

Mapping the alterations in glutamate with GluCEST MRI in a mouse model of dopamine deficiency.

Glutamate chemical exchange saturation transfer (GluCEST) MRI was used to measure metabolic changes in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by mapping regional cerebral glutamate. The GluCEST contrast following MPTP treatment was correlated with H-MR spectroscopy, motor function, and immunohistochemical measures. The GluCEST contrast was found to be significantly higher in the striatum and motor cortex of mice treated with MPTP than in controls (p < 0.

T1ρ Magnetic Resonance Imaging to Assess Cartilage Damage After Primary Shoulder Dislocation.

Background: Patients who suffer anterior shoulder dislocations are at higher risk of developing glenohumeral arthropathy, but little is known about the initial cartilage damage after a primary shoulder dislocation. T1ρ is a magnetic resonance imaging (MRI) technique that allows quantification of cartilage proteoglycan content and can detect physiologic changes in articular cartilage.

Purpose: This study aimed to establish baseline T1ρ MRI values for glenoid and humeral head cartilage, determine whether T1ρ MRI can detect glenohumeral cartilage damage after traumatic primary shoulder dislocation, and assess for patterns in cartilage damage in anterior shoulder dislocation.

High quality three-dimensional gagCEST imaging of in vivo human knee cartilage at 7 Tesla.

Purpose: To develop a new faster and higher quality three-dimensional (3D) gagCEST MRI technique for reliable quantification of glycosaminoglycan (GAG) present in the human knee cartilages.

Methods: A new magnetization-prepared 3D gradient echo-based MRI pulse sequence has been designed to obtain the B inhomogeneity, B inhomogeneity, and CEST Z-spectra images.

Results: The gagCEST values of different compartments of knee cartilage are calculated using a newly developed technique for healthy subjects and a symptomatic knee cartilage degenerated subject.