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).