Digitized cerebral synchrotron radiation angiography: Quantitative evaluation of the canine circle of Willis and its large and small branches

BACKGROUND AND PURPOSE: Conventional X-ray angiography lacks the sensitivit y and spatial resolution needed to detect small amounts of iodinated contra st material and to quantitate diameters of the small vessels in the brain. The purpose of this study was to ascertain whether digitized synchrotron ra diation microangiography, with the use of a high-definition TV camera syste m, can accurately show small cerebral vessels. METHODS: Six anesthetized dogs were exposed to monochromatic synchrotron ra diation with an energy level of 33.3 keV optimized for iodine detection whi le iodinated contrast material was injected into the brachiocephalic and ve rtebral arteries. The images were detected with a high-definition TV camera system with a spatial resolution of 30 mu m. In all, 26 cerebral angiogram s of the circle of Willis with its branches were obtained, and the images w ere digitized at a workstation. RESULTS: The small branches of the circle of Willis were clearly visible on all images. Vasodilatation of the circle of Willis and its large and small branches induced by CO2 inhalation was quantitatively confirmed on the ima ges: for example, the diameter of one small branch was increased from 0.24 +/- 0.04 mm to 0.38 +/- 0.12 mm, Temporal subtraction improved the image qu ality. CONCLUSION: The synchrotron radiation angiographic system is useful for vis ualizing large and small vessels deep in the brain as well as for quantitat ing their diameters.