High resolution MRI of the deep brain vascular anatomy at 8 tesla: Susceptibility-based enhancement of the venous structures

Purpose: The purpose of this work was to describe the deep vascular anatomy of the human brain using high resolution MR gradient echo imaging at 8 T. Method: Gradient echo images were acquired from the human head using a tran sverse electromagnetic resonator operating in quadrature and tuned to 340 M Hz. Typical acquisition parameters were as follows: matrix = 1,024 x 1,024, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, FOV = 20 cm, slice thick ness = 2 mm. This resulted in an in-plane resolution of similar to 200 mu m . Images were analyzed, and vascular structures were identified on the basi s of location and course. Results: High resolution ultra high field magnetic resonance imaging (UHFMR I) enabled the visualization of many small vessels deep within the brain. T hese vessels were typically detected as signal voids, and the majority repr esented veins. The prevalence of the venous vasculature was attributed larg ely to the magnetic susceptibility of deoxyhemoglobin. It was possible to i dentify venous structures expected to measure below 100 mu m in size. Perfo rating venous drainage within the deep gray structures was identified along with their parent vessels. The course of arterial perforators was more dif ficult to follow and not as readily identified as their venous counterparts . Conclusion: The application of high resolution gradient echo methods in UHF MRI provides a unique detailed view of particularly the deep venous vascula ture of the human brain.