Assessment of a simplified spin and gradient echo (sSAGE) approach for human brain tumor perfusion imaging.

The goal of this study was to validate a simplified spin- and gradient-echo (sSAGE) approach to obtain T-corrected dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) data in a clinical brain tumor population. A five-echo SAGE sequence was used to acquire DSC-MRI data (n=8 patients, 3 primary glioma, and 5 brain metastases). The ΔR and ΔR time series obtained from a nonlinear fit of all echoes (SAGE) were compared to ΔR and ΔR time series obtained analytically (sSAGE) using three echoes (two GEs and one SE).

Assessing tumor cytoarchitecture using multiecho DSC-MRI derived measures of the transverse relaxivity at tracer equilibrium (TRATE).

Purpose: In brain tumor dynamic susceptibility contrast (DSC)-MRI studies, multiecho acquisition methods are used to quantify the dynamic changes in T1 and T2 * that occur when contrast agent (CA) extravasates. Such methods also enable the estimation of the effective tissue CA transverse relaxivity. The goal of this study was to evaluate the sensitivity of the transverse relaxivity at tracer equilibrium (TRATE) to tumor cytoarchitecture.

Evaluation of a multiple spin- and gradient-echo (SAGE) EPI acquisition with SENSE acceleration: applications for perfusion imaging in and outside the brain.

Perfusion-based changes in MR signal intensity can occur in response to the introduction of exogenous contrast agents and endogenous tissue properties (e.g. blood oxygenation).

Assessment of a combined spin- and gradient-echo (SAGE) DSC-MRI method for preclinical neuroimaging.

The goal of this study was to optimize and validate a combined spin- and gradient-echo (SAGE) sequence for dynamic susceptibility-contrast magnetic resonance imaging to obtain hemodynamic parameters in a preclinical setting. The SAGE EPI sequence was applied in phantoms and in vivo rat brain (normal, tumor, and stroke tissue). Partial and full Fourier encoding schemes were implemented and characterized.

A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats.

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) can quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI requires an estimate of the time rate of change of the concentration of the contrast agent in the blood plasma, the vascular input function (VIF). Measuring the VIF in small animals is notoriously difficult as it requires high temporal resolution images limiting the achievable number of slices, field-of-view, spatial resolution, and signal-to-noise.

Comparison of dynamic contrast-enhanced MRI and quantitative SPECT in a rat glioma model.

Pharmacokinetic modeling of dynamic contrast-enhanced (DCE) MRI data provides measures of the extracellular-extravascular volume fraction (v(e) ) and the volume transfer constant (K(trans) ) in a given tissue. These parameter estimates may be biased, however, by confounding issues such as contrast agent and tissue water dynamics, or assumptions of vascularization and perfusion made by the commonly used model. In contrast to MRI, radiotracer imaging with SPECT is insensitive to water dynamics.