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Fig 4. First and second dynamic-phase MR angiography images in a 56-year-old male patient with a thoracolumbar aortic aneurysm to demonstrate the differentiation of the spinal cord inlet artery from the outlet vein. On the sagittal section of the first dynamic phase, the dilated aorta and its branching segmental arteries are selectively visualized with high intensities (A), whereas on the second-phase image their appearances are less bright, and segmental veins are visualized as well (D). Oblique coronal multiplanar reformation images (white lines) show at each vertebral level 1 segmental artery on each side of the vertebral column, except for the occluded right segmental artery at T9, on the first-phase image (B) and a combination of arteries and veins on the second-phase image (E). The reformation first-phase image targeted to the spinal canal depicts the inlet artery, that is, the AKA (arrow in C). On the reformation image of the second phase, the AKA displays decreased intensity relative to the first-phase image, whereas the draining vein (double arrow) is visualized more caudally (F), and the epidural venous plexus has become enhanced (*). Note that the midline vasculature most likely represents a combination of the ASA and anterior median vein, which remain spatially unresolved (arrowhead in C and F).
