| ABSTRACT: |
Thirty patients with failed back surgery syndrome
were studied to evaluate the effectiveness of magnetic resonance (MR) imaging
with gadolinium-diethylenetriaminepentaacetic acid/dimeglumine (Gd-DTPA)
in differentiating postoperative epidural fibrosis (scar) from recurrent
disk herniation. Pre- and postcontrast MR images were interpreted without
access to other diagnostic, surgical, or pathologic findings. Seventeen
patients had surgical and pathologic correlation of the MR findings at 19
disk levels. The precontrast studies had a sensitivity, specificity, and
accuracy of 100%, 71%, and 89%, respectively. The enhanced MR studies correctly
depicted the character of abnormal epidural soft tissue in 17 patients at
all 19 levels. Scar showed heterogeneous enhancement on the early T1-weighted
spin-echo images obtained within 10 minutes after contrast material administration.
Herniated disk did not show significant enhancement on the early studies
but showed variable degrees of enhancement on delayed images in nine of
12 cases. Other criteria were found to be less useful than the pattern of
enhancement. Results indicate that precontrast and early postcontrast T1-weighted
spin-echo studies are highly accurate in separating epidural fibrosis from
herniated disk. |