Selected centerlines. Centerlines of arteries and selections in white for tortuosity measurement were shown in maximum intensity projection (MIP). (top left) Right ICA was selected in white with progressive distance d in yellow. (top right) A lenticulostriate artery (LSA) of a normotensive subject was selected. (bottom left) The left to right ACA of a hypertensive patient was selected. (bottom right) The anterior cerebral artery (ACA) of a hypertensive subject was selected.