A Heparin Purification Process Removes Spiked Transmissible Spongiform Encephalopathy Agent.

In 2000, bovine heparin was withdrawn from the US market for fear of contamination with bovine spongiform encephalopathy (BSE) agent, the cause of variant Creutzfeldt-Jakob disease in humans. Thus, US heparin is currently sourced only from pig intestines. Availability of alternative sources of crude heparin, a life-saving drug, would benefit public health.

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities.

Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans.

Quantitative theory for the longitudinal relaxation time of blood water.

Purpose: To propose and evaluate a model for the blood water T1 that takes into account the effects of hematocrit fraction, oxygenation fraction, erythrocyte hemoglobin concentration, methemoglobin fraction, and plasma albumin concentration.

Methods: Whole blood and lysed blood T1 data were acquired at magnetic fields of 3 Tesla (T), 7T, 9.4T, and 11.

Natural D-glucose as a biodegradable MRI relaxation agent.

Purpose: Demonstrate applicability of natural D-glucose as a T2 MRI contrast agent.

Methods: D-glucose solutions were prepared at multiple concentrations and variable pH. The relaxation rate (R2  = 1/T2 ) was measured at 3, 7, and 11.

Hematocrit and oxygenation dependence of blood (1)H(2)O T(1) at 7 Tesla.

Knowledge of blood (1)H2O T1 is critical for perfusion-based quantification experiments such as arterial spin labeling and cerebral blood volume-weighted MRI using vascular space occupancy. The dependence of blood (1)H2O T1 on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 T using in vitro bovine blood in a circulating system under physiological conditions. Blood (1)H2O R1 values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model, which are described by a monoexponential longitudinal relaxation rate constant dependence.

Calibration and validation of TRUST MRI for the estimation of cerebral blood oxygenation.

Recently, a T(2) -Relaxation-Under-Spin-Tagging (TRUST) MRI technique was developed to quantitatively estimate blood oxygen saturation fraction (Y) via the measurement of pure blood T(2) . This technique has shown promise for normalization of fMRI signals, for the assessment of oxygen metabolism, and in studies of cognitive aging and multiple sclerosis. However, a human validation study has not been conducted.

Determination of whole-brain oxygen extraction fractions by fast measurement of blood T(2) in the jugular vein.

The oxygen extraction fraction of the brain reports on the balance between oxygen delivery and consumption and can be used to assess deviations in physiological homeostasis. This is relevant clinically as well as for calibrating blood oxygen level-dependent functional MRI responses. Oxygen extraction fraction is reflected in the arteriovenous difference in oxygen saturation fraction (Y(v) - Y(a) ), which can be determined from venous T(2) values when arterial oxygenation is known.

Magnetization transfer enhanced vascular-space-occupancy (MT-VASO) functional MRI.

Vascular-space-occupancy (VASO) MRI is a novel technique that uses blood signal nulling to detect blood volume alterations through changes in tissue signal. VASO has relatively low signal to noise ratio (SNR) because only 10-20% of tissue signal remain at the time of blood nulling. Here, it is shown that by adding a magnetization transfer (MT) prepulse it is possible to increase SNR either by attenuating the initial tissue magnetization when the MT pulse is placed before inversion, or, accelerating the recovery process when the pulse is applied after the inversion.