Direct estimation of O MR images (DIESIS) for quantification of oxygen metabolism in the human brain with partial volume correction.

Purpose: To provide a data post-processing method that corrects for partial volume effects (PVE) and fast decay in dynamic O MRI for the mapping of cerebral metabolic rates of oxygen consumption (CMRO ).

Methods: CMRO is altered in neurodegenerative diseases and tumors and can be measured after O gas inhalation using dynamic O MRI. CMRO quantification is difficult because of PVE.

3D CMRO mapping in human brain with direct O MRI: Comparison of conventional and proton-constrained reconstructions.

Oxygen metabolism is altered in brain tumor regions and is quantified by the cerebral metabolic rate of oxygen consumption (CMRO). Direct dynamic O MRI with inhalation of isotopically enriched O gas can be used to quantify CMRO; however, pixel-wise CMRO quantification in human brain is challenging due to low natural abundance of O isotope and, thus, the low signal-to-noise ratio (SNR) of O MR images. To test the feasibility CMRO mapping at a clinical 3 T MRI system, a new iterative reconstruction was proposed, which uses the edge information contained in a co-registered H gradient image to construct a non-homogeneous anisotropic diffusion (AD) filter.

Initial investigation of glucose metabolism in mouse brain using enriched O-glucose and dynamic O-MRS.

In this initial work, the in vivo degradation of O-labeled glucose was studied during cellular glycolysis. To monitor cellular glucose metabolism, direct O-magnetic resonance spectroscopy (MRS) was used in the mouse brain at 9.4 T.

Quantification of oxygen metabolic rates in Human brain with dynamic O MRI: Profile likelihood analysis.

Purpose: Parameter identifiability and confidence intervals were determined using a profile likelihood (PL) analysis method in a quantification model of the cerebral metabolic rate of oxygen consumption (CMRO ) with direct O MRI.

Methods: Three-dimensional dynamic O MRI datasets of the human brain were acquired after inhalation of O gas with the help of a rebreathing system, and CMRO was quantified with a pharmacokinetic model. To analyze the influence of the different model parameters on the identifiability of CMRO , PLs were calculated for different settings of the model parameters.

Toward biocompatible nuclear hyperpolarization using signal amplification by reversible exchange: quantitative in situ spectroscopy and high-field imaging.

Signal amplification by reversible exchange (SABRE) of a substrate and parahydrogen at a catalytic center promises to overcome the inherent insensitivity of magnetic resonance. In order to apply the new approach to biomedical applications, there is a need to develop experimental equipment, in situ quantification methods, and a biocompatible solvent. We present results detailing a low-field SABRE polarizer which provides well-controlled experimental conditions, defined spins manipulations, and which allows in situ detection of thermally polarized and hyperpolarized samples.

Direct cerebral and cardiac 17O-MRI at 3 Tesla: initial results at natural abundance.

Purpose: To establish direct (17)O-magnetic resonance imaging (MRI) for metabolic imaging at a clinical field strength of 3 T.

Methods: An experimental setup including a surface coil and transmit/receive switch was constructed. Natural abundance in vivo brain images of a volunteer were acquired with a radial three-dimensional (3D) sequence in the visual cortex and in the heart with electrocardiogram (ECG)-gating.

A battery-driven, low-field NMR unit for thermally and hyperpolarized samples.

Object: The design of a multinuclear low-field NMR unit with variable field strength <6 mT providing accurate spin manipulations and sufficient sensitivity for direct detection of samples in thermal equilibrium to aid parahydrogen-based hyperpolarization experiments.

Materials And Methods: An optimized, resistive magnet connected to a battery or wall-power driven current source was constructed to provide a magnetic field <6 mT. A digital device connected to a saddle-shaped transmit- and solenoid receive-coil enabled MR signal excitation and detection with up to 10(6) samples/s, controlled by a flexible pulse-programming software.