This work describes a methodology for in vivo MR imaging of arteries and veins within the visual cortex of the cat brain. Very high magnetic fields (9.4 T) and small field-of-view 3D acquisitions were used to image the neurovasculature at resolutions approaching the microscopic scale. A combination of time-of-flight MR angiography and T*2-weighted imaging, using both endogenous BOLD contrast and an exogenous iron-oxide contrast agent, provided high specificity for distinguishing between arteries and veins within the cortex. These acquisition techniques, combined with 3D image processing and display methods, were used to detect and visualize intracortical arteries and veins with diameters smaller than 100 μm. This methodology can be used for visualizing the neurovasculature or building models of the vascular network and may benefit a variety of research applications including fMRI, cerebrovascular disease, and cancer angiogenesis.
Bibliographical noteFunding Information:
This work was supported by the NIH grants R01MH070800, R21EB004460, and R01CA092004; the NIH (NCRR) grant P41-RR008079; and the MIND Institute. Instrument acquisition was in part funded by the Keck Foundation.