Magnetic resonance angiography of collateral blood supply to spinal cord in thoracic and thoracoabdominal aortic aneurysm patients

Anatomic drawing shows the different blood-supplying trajectories to the thoracolumbar spinal cord in thoracoabdominal aortic aneurysm patients. The segmental artery directly connecting to the Adamkiewicz artery is partially occluded. The Adamkiewicz artery is supplied by a proximal intersegmental collateral, which originates from a segmental artery two vertebral levels below. This trajectory does not represent the only route for the blood to reach the spinal cord. Alternative original trajectories include the anterior radiculomedullary arteries deriving from the vertebral arteries and the filum terminale artery originating from the iliolumbar artery. 1, Spinal cord; 2, vertebral artery; 3, anterior spinal cord; 4, left subclavian artery; 5, aneurysmatic aorta; 6, Adamkiewicz artery; 7, intersegmental collateral; 8, segmental artery indirectly supplying the Adamkiewicz artery; 9, anastomotic loop to the posterior spinal artery; 10, filum terminale artery; 11, common iliac artery; 12, external iliac artery; 13, internal iliac artery (hypogastric artery); 14, iliolumbar artery.

This flow chart shows the classification of the patients in different groups. AKA, Adamkiewicz artery; MEPs, motor-evoked potentials, SA, segmental artery; TAA, thoracic abdominal aneurysm; TAAA, thoracoabdominal aortic aneurysm.

Curved multiplanar reformation of a contrast-enhanced magnetic resonance angiographic examination consisting of two consecutive dynamic phases illustrates the identification of the Adamkiewicz artery (single arrow) and the great anterior radiculomedullary vein (double arrow). Note that the signal intensity of the Adamkiewicz artery relatively decreases from the (a) first to the (b) second dynamic phase, while the filling of the vein becomes more complete. The midline vasculature (arrow head) resembles the spatially unresolved combination of the anterior spinal artery and the anterior median vein. Note that the venous plexus (*) enhances only in the second-phase image.

a, Preoperative contrast-enhanced magnetic resonance angiography of a 63-year-old woman with a type II thoracoabdominal aortic aneurysm shows that the collateral arteries arise from the pelvic region outside the cross-clamped aortic region (double cross-bars) and that the intersegmental collaterals (arrowheads) vertically interconnect the segmental arteries. b, This panel shows that the original direct segmental supply (SA*) to the Adamkiewicz artery (AKA) at T 12 and the anterior spinal artery (ASA) are partially occluded and that the segmental artery one level more caudally (SA) indirectly provides the blood supply.

Preoperative contrast-enhanced magnetic resonance angiography of a 62-year-old man with a type III thoracoabdominal aortic aneurysm shows a well-developed network of collateral arteries (arrowheads) originating from the iliolumbar arteries (arrow). Note that this remote collateral supply is the most dominant supply to the thoracolumbar spinal cord. Intraoperative motor-evoked potentials remained stable.

Preoperative contrast-enhanced magnetic resonance angiography of a 32-year-old man with a type II thoracoabdominal aortic aneurysm shows that well-developed collateral arteries originate from both the pelvic arteries (white arrowheads) and high thoracic regions (open arrowheads). Intraoperative motor-evoked potentials remained stable.

In this preoperative contrast-enhanced magnetic resonance angiography of a 58-year-old man with type II thoracoabdominal aortic aneurysm, no collateral arteries were identified. Intraoperative motor-evoked potentials declined during aortic cross-clamping but returned after selective revascularization.

a, Preoperative contrast-enhanced magnetic resonance angiography (MRA) of a 46-year-old man with a type II thoracoabdominal aortic aneurysm. b, The postoperative MRA shows strong development of the remote collateral arterial supply from the pelvic region after aortic repair. Intraoperative motor-evoked potentials remained stable.