Preoperative visualization of the artery of Adamkiewicz by intra-arterial CT angiography

BACKGROUND AND PURPOSE: CT and MR angiographies have been reported to visualize the artery of Adamkiewicz (AKA) noninvasively to prevent spinal cord ischemia in surgery of thoracic descending aortic aneurysms. The purpose of this work was to compare the usefulness of CT angiography (CTA) with intra-arterial contrast injection (IACTA) with that of conventional CTA with intravenous contrast injection (IVCTA).MATERIALS AND METHODS: We enrolled 32 consecutive patients with thoracic or thoracoabdominal aortic aneurysms who were scheduled for surgical repair or endovascular stent-graft treatment. All of the CTA images were obtained using a 16-detector row CT scanner and 100 mL of contrast material (370 mg/mL) injected at a rate of 5 mL/s. Contrast was injected via the antecubital veins of 15 patients and via a pig-tail catheter placed at the proximal portion of the descending aorta in 17 patients who underwent IVCTA and IACTA, respectively. Two datasets were reconstructed from 2 consecutive scans. The AKA was identified as a characteristic hairpin curved vessel in the anterior midsagittal surface of the spine and by the absence of further enhancement in the second rather than in the first phase. Continuity between the AKA and aorta was confirmed when the vessel could be traced continuously by paging the oblique coronal multiplanar reconstruction or original axial images.RESULTS: Intra-arterial contrast injection was significantly more sensitive in identifying the AKA than IVCTA: 16 (94.1%) of 17 versus 9 (60.0%) of 15 (P = .033). Continuity between the AKA and aorta through intercostal or lumbar artery was confirmed in 14 (87.5%) of 16 and 5 (55.6%) of 9 of the IACTA and IVCTA groups, respectively.CONCLUSION: Intra-arterial contrast injection detected the AKA at a high rate and verified continuity from the aorta to the AKA.

Paraplegia and paraplesis secondary to spinal cord ischemia remain serious complications of surgical repair or of endovascular treatment for descending thoracic aortic aneurysm (TAA) or thoracoabdominal aortic aneurysm (TAAA). The incidence ranges between 5% and 11% of thoracoabdominal surgeries.^1–4 The great anterior radiculomedullary artery (the artery of Adamkiewicz [AKA]) is the dominant feeder of the spinal cord. One possible cause of spinal cord ischemia during surgery is failure to reestablish the spinal cord blood supply, and many reports have stressed the importance of reattaching the intercostal or lumbar arteries related to the AKA.^5,6 Preoperative AKA identification and display of intercostal and lumbar arteries help surgeons to determine the appropriate range of aortic lesions that require graft replacement and intercostal or lumbar arteries requiring reconstruction.⁷The most reliable way to visualize the AKA is selective intercostal arterial angiography, the detection rate of which is 43%–86%.^8–12 However, selective angiography is time consuming, and complications including spinal cord injury can develop.^10,11 Recently, MR angiography (MRA)^13–18 and CT angiography (CTA)^17–21 have been used to visualize the AKA less invasively with reported detection rates of 67%–93% and 68%–90%, respectively. However, these rates could be further improved.The AKA is a small vessel with a diameter of 0.5–1.5 mm^22,23 that is surrounded by osseous structures. In addition, intercostal or lumbar arteries and dorsal branches run very close to the osseous structures (Fig 1). Due to these anatomic features, the contrast-to-noise ratio (CNR) in the spinal canal is decreased, and the AKA and its continuity with the aorta can be obscured. Robust aortic contrast enhancement is necessary to detect small vessels, but CTA with intravenous contrast injection (IVCTA) has limitations with respect to elevating aortic enhancement, because contrast material is diluted in the circulation of the right side of the heart. Nojiri et al²⁴ showed that CTA with intra-arterial contrast injection (IACTA) could track the AKA to the aorta because of high contrast. The present study compares the abilities of IACTA and IVCTA to detect the AKA.Open in a separate windowFig 1.Anatomic course of the AKA. Right anterosuperior view of a 3D volume-rendered CT image of IACTA with semitransparent skeletal system. Intercostal and lumbar arteries (1) originate from the aorta, and divide into posterior (2) and anterior (3) branches. Anterior branches run through the intercostal groove. Posterior branches subdivide into the radiculomedullary artery (4) and muscular branch (5). Radiculomedullary artery courses to the spine and enters the vertebral foramen. The AKA (6) is the largest anterior radiculomedullary artery and joins the anterior spinal artery (7) in a characteristic hairpin curve.