Article
Postoperative imaging of vestibular schwannomas – interobserver variabilty between the neurosurgeon and the neuroradiologist
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Published: | May 13, 2014 |
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Objective: Postoperative contrast-enhanced MR imaging (MRI) allows the assessment of residual or recurrent tumor. Signal enhancements particularly in the internal auditory canal are frequently observed. The differentiation between residual tumor and postoperative changes remains challenging.
Method: 112 patients were included in a prospective, multicenter, clinical phase III trial in order to evaluate the efficacy of prophylactic nimodipine treatment in vestibular schwannoma surgery. Extent of resection was documented according to the intraoperative findings of the surgeon. Postoperative MRIs were performed 3–6 months after surgery and evaluated by the neurosurgeon and by an independent and blinded neuroradiologist. Extent of resection was classified in complete and residual tumor of 1–3 mm, 3–10 mm and >10 mm respectively.
Results: Postoperative MRI findings were equally assessed in only 24% of the cases. Surgeons tended to judge a higher rate of radical excision. The intraoperative findings of the surgeons were comparable with the surgeons' evaluation of the postoperative MRIs in 80%. Main difference was diverging interpretation of enhancements in the auditory canal.
Conclusions: The assessment of postoperative MRIs following vestibular schwannoma surgery significantly differed between the neurosurgeon and the neuroradiologist. A tendency and therefore a potential surgical bias for a higher extent of resection were observed. The benefit of early postoperative MRIs following vestibular schwannoma surgery has to be discussed. For clarification long-term observations are essential.