Mr contrast due to intravascular magnetic susceptibility perturbations

摘要: A particularly powerful paradigm for functional MR imaging of microvascular hemodynamics incorporates paramagnetic materials that create significant image contrast. These include exogenous (lanthanide chelates) and endogenous (de-oxygenated hemoglobin) agents mapping cerebral blood volume neuronal activity, respectively. Accurate interpretation these maps requires an understanding the bio-physics susceptibility-based The authors developed a novel Monte Carlo model with which quantified relationship between microscopic tissue parameters, NMR susceptibility contrast in vivo. found vascular permeability to water flow erythrocytes be relatively unimportant contributors susceptibility-induced ΔR2. However, pulse sequence, echo time, concentration agent have profound effects on vessel size dependence For vasculature containing both capillaries venules, predicted linear fraction physiological changes based recruitment dilation, is nonlinear sequence dependent. Using model, demonstrated spin images greater sensitivity than gradient images, specifics transverse relaxivity change should allow robust relative volume. also excellent agreement predictions their experimental data obtained from serial injection superparamagnetic rat model.