MR-ANGIOGRAPHY OF NORMAL INTRADURAL VESSELS OF THE THORACOLUMBAR SPINE

PURPOSE: To identify and describe the normal intradural vessels detect ed on MR angiograms of the thoracolumbar spine. METHODS: Six adult sub jects who had clinical evidence of myelopathy, yet normal findings at spinal digital subtraction angiography (DSA), were also studied withou t and with contrast-enhanced MR imaging and three-dimensional time-of- flight, single-slab MR angiography. Sagittal and coronal subvolume (ta rgeted) maximum intensity projection images were compared with arteria l and venous phase DSA images. Angiographic images were then compared with postmortem, formalin-fixed cord specimens. RESULTS: Recognizable intradural vessels were detected only on contrast-enhanced MR angiogra ms. These vessels corresponded to the posterior and/or anterior median (midline) veins and the great medullary veins, The median veins had v ariable but mild tortuosity. The medullary veins, which extended from the median veins and coronal venous plexus on the cord surface to the epidural venous plexus, were relatively straight and usually located a t T-12 or L-1. The anterior spinal artery could partially contribute t o the anterior midline vascular signal. CONCLUSION: The intradural ves sels identified on contrast-enhanced MR angiograms are primarily veins , and these are usually the largest vessels on or near the cord surfac e. The limited number and minimal tortuosity of these veins may serve as a baseline for the examination of patients with clinically suspecte d arteriovenous malformation or fistula.