In vivo cerebromicrovasculatural visualization using 3D ΔR2-based microscopy of magnetic resonance angiography (3DΔR2-mMRA)

This study proposed a novel methodology for depicting cerebral small vessels including veins, arterioles, and venules, called 3DΔR2-mMRA (three-dimensional, steady-state ΔR2-based, and flow-independent microscopic magnetic resonance angiography). The ΔR2 map calculated by a fast spin-echo imaging technique before and after the injection of an iron-oxide contrast agent was used to delineate the relative cerebral blood volume, primarily to microvasculature. The proposed 3DΔR2-mMRA method, which employs 3D reconstruction techniques, can simultaneously provide high-resolution 3D information on the cerebral anatomy, in vivo microvascular architecture, and hemodynamic response, which can be used to evaluate pathological microvascular changes over time in cerebromicrovascular disease. Since spin-echo-based ΔR2 imaging was applied, the inflow effects, susceptibility artifacts, and the overestimation of vessel size in brain were reduced. A well-defined three-vessel occlusion model in the rat was performed to evaluate the capability of the proposed method in evaluating alterations to the microvasculature.