BACKGROUND AND PURPOSE: The measurement of ischemic lesion volume on diffusion- (DWI) and perfusion-weighted MRI (PWI) is examiner dependent. We sought to quantify the variance imposed by measurement error in DWI and PWI lesion volume measurements in ischemic stroke.
BACKGROUND AND PURPOSE: Leukoaraiosis (LA) is associated with structural and functional vascular changes that may compromise tissue perfusion at the microvascular level. We hypothesized that the volume of LA correlated with the proportion of initially ischemic but eventually infarcted tissue in acute human stroke.
BACKGROUND AND PURPOSE: Based on previous observations that infarcts encompassing the insula were linked to unfavorable clinical outcome, we hypothesized that insular damage was directly associated with worsened infarction in ischemic but potentially viable neighboring brain tissue.
OBJECTIVE: The level of anticoagulation at the time of stroke onset may influence the size, composition, and dissolution rate of the occlusive clot. We explored the relation between admission international normalized ratio (INR) and acute infarct volume in patients with ischemic stroke.
The design of effective pH responsive MRI contrast agents is a key goal in the development of new diagnostic methods for conditions such as kidney disease and cancer. A key factor determining the effectiveness of an agent is the difference between the relaxivity of the "on" state compared to that of the "off" state. In this paper, we demonstrate that it is possible to improve the pH-responsive action of a low molecular weight agent by conjugating it to a macromolecular construct. The synthesis of a bifunctional pH responsive agent is reported.
We formalize the pair-wise registration problem in a maximum a posteriori (MAP) framework that employs a multinomial model of joint intensities with parameters for which we only have a prior distribution. To obtain an MAP estimate of the aligning transformation alone, we treat the multinomial parameters as nuisance parameters, and marginalize them out. If the prior on those is uninformative, the marginalization leads to registration by minimization of joint entropy.
Three algorithms for solving linearized systems of RF waveform design equations for calculating accelerated spatially-tailored excitations on parallel excitation MRI systems are presented. Their artifact levels, computational speed, and RF peak and root-mean-square (RMS) voltages are analyzed. An SVD-based inversion method is compared with conjugate gradient least squares (CGLS) and least squares QR (LSQR), two iterative algorithms designed to solve large linear systems.
The GdIII-based magnetic resonance imaging contrast agent MS-325 targets the blood protein serum albumin, resulting in an increased efficacy (relaxivity) as a relaxation agent. MS-325 showed different relaxivities when bound to serum albumin from different species, e.g., r1=30.5 mM-1 s-1 (rabbit) vs 46.3 mM-1 s-1 (human) at 35 degrees C and 0.47 T. To investigate the mechanism for this difference, surrogate complexes were prepared where the GdIII ion was replaced by other LnIII ions.
Investigators often study rats by microCT to investigate the pathogenesis and treatment of skeletal disorders in humans. However, microCT measurements provide information only on bone mineral content and not the solid matrix. CT scans are often carried out on cancellous bone, which contains a significant volume of marrow cells, stroma, water, and fat, and thus the apparent bone mineral density (BMD) does not reflect the mineral density within the matrix, where the mineral crystals are localized.
Extraversion and neuroticism are two important and frequently studied dimensions of human personality. They describe individual differences in emotional responding that are quite stable across the adult lifespan. Neuroimaging research has begun to provide evidence that neuroticism and extraversion have specific neuroanatomical correlates within the cerebral cortex and amygdala of young adults. However, these brain areas undergo alterations in size with aging, which may influence the nature of these personality factor-brain structure associations in the elderly.
