Artikel
Dynamics of contrast enhancement in vestibular schwannomas
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Autoren
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C. Scheller
- Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
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S. Rampp
- Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
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J. Prell
- Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
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J. Rachinger
- Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
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C. Strauss
- Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
| Veröffentlicht: | 20. Mai 2009 |
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Gliederung
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Objective: Since the first treatment of vestibular schwannomas with the gamma knife by Leksell there discussion has been ongoing about the evaluation of tumor response after radiosurgery. The efficacy of treatment is verified by post treatment contrast-enhanced magnetic resonance imaging (MRI) evaluating the development of tumor size and changes in contrast enhancement. While loss of central enhancement was shown to reflect central necrosis, reliability and consistency of the method has not yet been investigated in detail. This is the first study to investigate the influence of delay between contrast agent administration and MRI acquisition on vestibular schwannoma contrast uptake.
Methods: We investigated 15 consecutive cases with vestibular schwannomas. Dynamics of contrast uptake were evaluated with T1-weighted axial MRI sequences which were performed 0, 1, 3, 4, 9, and 10 minutes after administration of gadolinium. Tumors were segmented manually to evaluate gadolinium uptake at each time point using detailed voxel-intensity analysis.
Results: Detailed analysis revealed considerable influence of time from administration to acquisition on contrast enhancement. Intensity increase related to images at time 0, reflecting uptake of contrast agent, showed a median variation of 22% (range 7–70%). Inhomogeneity of intensity within the tumor volume, measuring central necrosis, presented with a median of 26% (range 4–60%).
Conclusions: Contrast enhancement of vestibular schwannomas varies dependent on the delay between agent administration and MRI acquisition. So-called “necrotic tumor areas” may be falsely detected because of wrong timing. In addition, this underlines the surgical experience that “necrotic areas” on MRI may not be consistent with intraoperative findings. In previously irradiated schwannomas, contrast uptake may therefore be not indicative of effective radiotherapy. A standardized MRI protocol with identical timing of image acquisition following contrast administration may increase comparability of contrast uptake in vestibular schwannomas.
