Abstract
Conventional MR imaging can provide important clues regarding the location of a spinal vascular malformation. We hypothesized that a dilated vein of the filum terminale, identified as a curvilinear flow void on T2WI, could be an imaging marker for a lower lumbar (L3-L5) or sacral fistula. We retrospectively identified all spinal dural and spinal epidural arteriovenous fistulas from 2 large tertiary referral centers from 2005 to 2018. All patients had a lumbar spinal MR imaging and a conventional spinal angiography. Images were reviewed by 2 neuroradiologists who categorized the level of the arterial feeder to the fistula and the presence or absence of a dilated vein of the filum terminale on T2WI and T1 postcontrast images. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula. One hundred sixty-two patients were included. An enlarged filum terminale vein was identified in 39 patients. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula were 86%, 98.3%, 94.9%, and 95.1%, respectively. The presence of a dilated vein of the filum terminale can accurately localize a spinal dural arteriovenous fistula/spinal epidural arteriovenous fistula to the lower lumbar or sacral spine in patients being evaluated for such lesions. This finding can be used to facilitate both noninvasive and conventional spinal angiography.
Highlights
BACKGROUND AND PURPOSEConventional MR imaging can provide important clues regarding the location of a spinal vascular malformation
The presence of a dilated vein of the filum terminale can accurately localize a spinal dural arteriovenous fistula/spinal epidural arteriovenous fistula to the lower lumbar or sacral spine in patients being evaluated for such lesions
A spinal CT angiogram or time-resolved large-FOV MR angiogram is obtained to get a sense of the location of the arterial feeders so that spinal angiography can be focused on a few levels.[8,9,10,11]
Summary
Patient Selection Following institutional review board approval at 2 institutions, we retrospectively identified all patients with SDAVFs and SEDAVFs who underwent lumbar spinal MR imaging and conventional spinal angiography from 2005 to 2018. All patients had an angiographically confirmed SDAVF or SEDAVF. Children and patients who did not consent to the use of their charts for retrospective research were excluded. Perimedullary, and metameric-type vascular malformations were excluded. Imaging Review Images were reviewed by 2 diagnostic and interventional neuroradiologists. The neuroradiologists were blinded to the level and type of fistula at the time of MR imaging interpretation. Following interpretation of the MR images, the 2 neuroradiologists reviewed the conventional spinal angiograms and identified the location of the arterial feeder to the spinal vascular malformation as well as the type of spinal vascular malformation (SEDAVF versus SDAVF)
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