Normal Anterior Spinal Arteries within the Cervical Region: High-Spatial-Resolution Contrast-enhanced Three-dimensional MR Angiography

Abstract

To determine retrospectively whether the anterior spinal artery (ASA) is visualized in the cervical region with contrast material-enhanced high-spatial-resolution three-dimensional magnetic resonance (MR) angiography of the extracranial carotid and vertebral arteries. The institutional research ethics committee approved this study and provided a waiver for informed consent. Data sets were evaluated in 50 consecutive patients referred for contrast-enhanced three-dimensional MR angiography of the carotid arteries (32 male and 18 female patients; age range, 15-80 years; mean age, 59 years). The ASA was defined as a linear area of high signal intensity that is seen anterior to the spinal cord in an arterial phase of enhancement and connects directly to a known arterial structure. If the linear area of high signal intensity was seen in the arterial phase but did not connect to a known arterial structure, it was considered a probable ASA. Venous enhancement was graded on a five-point scale (0-4) with grade 0 (no venous enhancement) or grade 1 (trace venous enhancement) considered to be in the arterial phase. The ASA was identified with certainty in 37 of 50 patients. A vessel visualized anterior to the spinal cord, which probably represented the ASA, was seen in another 11 of 50 patients. In 29 of 50 patients the vessel was visualized only on the full-volume maximum intensity projection (MIP) image. In the remainder of cases the artery was identified on operator-defined subvolume MIP images. Continuity between the vessel and the vertebrobasilar arterial structures was identified in 35 of 50 patients. The vessel was seen as a continuous structure throughout its length in 34 patients and appeared discontinuous in 14. Radiculomedullary feeders were identified in 24 of 50 patients. The normal cervical ASA was visualized in 48 of 50 of subjects with contrast-enhanced high-spatial-resolution three-dimensional MR angiography.