American Journal of Roentgenology, Vol 167, 217-223, Copyright © 1996 by American Roentgen Ray Society
Clinical impact of contrast-enhanced MR imaging reports in patients with previous lumbar disk surgery
PC Milette, S Fontaine, L Lepanto, R Dery and G Breton
Department of Radiology, Hopital Saint-Luc, Montreal, Quebec, Canada.
OBJECTIVE. We wanted to assess the clinical impact of the reports of
contrast-enhanced MR imaging on the decision to repeat surgery and on the
results of repeat surgery in patients with previous lumbar disk surgery.
SUBJECTS AND METHODS. We interviewed 257 patients who had undergone lumbar
disk surgery and who showed symptoms suggesting persistent or new disk
herniation. We conducted our interviews 6-18 months after patients had
undergone contrast-enhanced MR imaging. We then correlated patient outcome
with original MR findings. RESULTS. Fifty-two patients underwent new
surgical procedures after their MR examination. Findings of disk herniation
on MR images were associated with a significantly greater frequency of
repeat surgery. The size of main herniation seen on MR images was also a
significant variable. Patients with Worker's Compensation Insurance files
had significantly worse prognoses: Only two (8%) of 26 of these patients
reported 50% improvement 1 year after repeat surgery. However, only 6 (23%)
of 26 non-Worker's Compensation patients reported 50% improvement 1 year
after surgery. CONCLUSION. Despite its documented high anatomic accuracy,
the clinical usefulness of enhanced MR imaging for patients with previous
lumbar disk surgery needs further evaluation. In our series, findings of
disk herniations on enhanced MR examinations were associated with a greater
frequency of repeat surgery, but such surgery relieved symptoms in few
patients. The influence of enhanced MR imaging on the decision for repeat
surgery and on the type of surgery may be misleading. Selection criteria
for repeat surgery need to be reassessed using rigorous outcome research
protocols.