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Detection of Spinal Dural Arteriovenous Fistulae with MR Imaging and Contrast-Enhanced MR Angiography: Sensitivity, Specificity, and Prediction of Vertebral Level

Efrat Saraf-Lavia, Brian C. Bowena, Robert M. Quencera, Evelyn M.L. Sklara, Alan Holza, Steve Falconea, Richard E. Latchawc, Robert Duncanb and Ajay Wakhlooa

a Department of Radiology, University of Miami School of Medicine, Miami, FL
b Department of Epidemiology & Public Health, University of Miami School of Medicine, Miami, FL
c Department of Radiology, University of California, Davis, Davis, CA



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  		FIG 1. True positive result: left T12 dural AVF. All three reviewers thought that a fistula was present based on MR imaging (true positive, A and B) and based on MR imaging plus MR angiography (true positive, A–E).

A, Fast spin-echo T2-weighted MR image shows hyperintense cord from T9 to the conus tip and serpentine flow voids, consistent with enlarged intradural vessels, posterior to the cord from T6 to T10.

B, Contrast-enhanced T1-weighted MR image shows patchy enhancement within the cord from T9 to the conus tip.

C, Sagittal view maximum intensity projection image shows marked tortuosity of the posterior perimedullary vessel.

D, Coronal view maximum intensity projection image, targeted to the posterior half of the spinal canal.

E, Coronal view maximum intensity projection image, targeted to the mid-portion of the canal at the foraminal level, shows an enlarged, tortuous vessel (arrow) extending toward the left T12 foramen. The left T12 vessel corresponds to the posterior medullary vein.

F, Posteroanterior view DSA, obtained after injection of the dorsal ramus of the left T12 intercostal artery, shows the fistula (arrowhead) and draining medullary vein (arrow).



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  		FIG 2. False negative result: right L1 dural AVF. None of the reviewers thought that a fistula was present based on MR imaging alone (false negative, A and B). After evaluating the MR angiograms, reviewer 2 thought that a dural AVF was present (true positive, A–D) and correctly predicted the fistula level at L1.

A, Midsagittal T2-weighted fast spin-echo MR image shows abnormal increased signal intensity in the cord from T8 to T10.

B, Contrast-enhanced T1-weighted MR image shows patchy enhancement in the cord from T8 to T10, as well as enhancing anterior (white arrow) and smaller posterior (black arrow) midline vessels.

C, Sagittal view maximum intensity projection image shows marked tortuosity of the anterior vessel(s), which is not as evident on the routine MR images shown in A and B.

D, Coronal view maximum intensity projection image, which encompasses the anterior half of the canal, reveals the continuity of a tortuous right L1 anterior medullary vein (short arrow) with the anterior median vein (long arrow).

E and F, Posteroanterior view DSA, obtained after injection of the right L1 lumbar artery, show the fistula (arrowhead) and draining medullary vein (arrows).



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  		FIG 3. Graph depicts detection of intradural flow voids on T2-weighted MR images. DAVF (proven fistula) and CONTROL refer to the study groups; R1, R2, and R3 refer to the reviewers.



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  		FIG 4. Graph depicts detection of intradural serpentine enhancement on contrast-enhanced T1-weighted MR images. DAVF and CONTROL refer to the study groups; R1, R2, and R3 refer to the reviewers.



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  		FIG 5. Graph depicts detection of more than two major vessels on the cord surface on MR angiography source and maximum intensity projection images. DAVF and CONTROL refer to the study groups; R1, R2, and R3 refer to the reviewers.



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  		FIG 6. Graph depicts mean tortuosity of the dominant intradural vessel on MR angiograms. CONTROL (n = 11) and DAVF (n = 20) refer to the study groups. The ordinate (y axis) has units of "turns/vertebral segment." Error bars indicate standard error of the mean.



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  		FIG 7. Graph depicts mean length of the dominant intradural vessel on MR angiograms. CONTROL (n = 11) and DAVF (n = 20) refer to the study groups. The ordinate (y axis) has units of "vertebral segments." Error bars indicate standard error of the mean.



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  		FIG 8. False positive result for reviewers 1 and 2: normal intradural vessels. Both reviewers thought that a fistula was present based on MR imaging (false positive, A–C) and based on MR imaging plus MR angiography (false positive, A–E).

A, Midsagittal T2-weighted fast spin-echo MR image shows normal size and signal intensity of the cord.

B and C, Contrast-enhanced T1-weighted MR images show no intrinsic cord enhancement. Enhancing linear segments (arrows) on the cord surface are noted.

D, Contrast-enhanced MR angiogram. Sagittal view maximum intensity projection image encompasses the midline vessels. The vessels (arrows) correspond to the anterior and posterior median veins.

E, Coronal view maximum intensity projection image encompasses approximately the anterior 10% to 20% of the canal and shows a midline vessel (arrow) with features of the anterior median vein.



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  		FIG 9. Graph depicts sizes of dominant intradural vessels on MR angiograms. DAVF (n = 20) and CONTROL (n = 11) refer to the study groups; R1, R2, and R3 refer to the reviewers. Small, medium, and large refer to qualitative estimates of size, as described in the text.



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  		FIG 10. Graphs depict estimation of vertebral levels of dural AVF by reviewers 1, 2, and 3 based on MR imaging alone (squares) and based on MR imaging plus MR angiography (triangles). Numbers on the y axis refer to the deviation (in vertebral segments) of the estimates from the correct levels of the fistulae (positive numbers, craniad; negative numbers, caudad). Numbers on the x axis are the case numbers assigned to the patients with documented dural AVF. The absence of a square or triangle for a case indicates that the reviewer did not suspect fistula (false negative) or that fistula was suspected but the level was indeterminate. MRI, MR imaging; MRA, MR angiography.





Copyright © 2009 by the American Society of Neuroradiology. Print ISSN: 0195-6108 Online ISSN: 1936-959X