CONTRAST-ENHANCED MR-IMAGING IN THE DIAGNOSIS OF THE FAILED BACK SURGERY SYNDROME - A PROSPECTIVE-STUDY OF 109 PATIENTS

In a prospective study, 132 previously operated disc levels in 109 patients with failed back surgery syndrome (FBSS) were examined by MR imaging before and after intravenous application of a contrast agent (0.1 mmol Gd-DTPA/kg). The results were compared with current CT findings in 47 cases. The images were randomized and independently assessed by two experienced radiologists. A second intervention of a total of 30 disc levels was performed in 28 patients. Contrast-enhanced-MR imaging (CE-MRI) improved the differentiation of scar from recurrent disc herniation (RDH) compared to plain MRI and CT. Agreement between the two readers was significantly higher for CE-MRI than for the other two procedures (p less-than-or-equal-to 0,001). CE-MRI additionally had the highest diagnostic accuracy (p less-than-or-equal-to 0.001). The preoperative diagnosis made by CE-MRI was confirmed in 27 (90 %) of the reoperated disc levels. Quantitative evaluation showed that there was no contrast enhancement in RDH as opposed to pronounced enhancement of 122% in scars (p less-than-or-equal-to 0.001). Evaluation with respect to scar age revealed a significant difference (p less-than-or-equal-to 0.01) in contrast enhancement between scars less and more than 2.5 years old.