gms | German Medical Science

Introduction: Both, intraoperative MRI (iMRI) and 5-ALA fluorescence represent appropriate means to maximize extent of resection in brain tumor surgery. Our aim was to report on the surgical outcome of using both modalities in the surgical treatment of patients with suspected malignant gliomas.

Material and methods: 50 patients with contrast enhancing lesions were prospectively included. All patients received 5-ALA (20 mg/kg) prior to surgery. Tumor resections were performed under white light conditions until the surgeon was convinced to have resected the intended amount of tissue, before an intraoperative MRI scan was obtained and blue light subsequently turned on. All patients had detailed histopathological assessment of tumor specimens and received early postoperative MRI to determine the extent of resection. Complete resection (CR) was defined as absence of residual contrast enhancement. All patients had adjuvant treatment according to histology.

Results: IMRI revealed residual contrast enhancing tissue in 20 cases (40%). Under blue light, residual fluorescence was visible in 17 patients (34%). CR was achieved in 39 patients (78%). All additionally resected tissue specimens were positive for pathological tissue; both modalities were consistent in indicating presence or absence of residual tumor in 11 (22%) and 13 (26%) cases, respectively. Histology revealed glioblastoma in 37 patients (74%), 13 patients (26%) suffered from other entities (e.g., WHO grade III gliomas or metastases). Kaplan Meier analysis rendered a median overall survival of 18.8 months for patients with glioblastomas, and 31.4 months for other patients. The rate of new neurological deficits was acceptable (12%), and only 2 patients experienced severe deficits (4%) with long-term decline of KPS score.

Conclusion: 5-ALA and iMRI represent valuable surgical tools that are not exclusive but supplementary in terms of detection of unintentionally remaining tissue. Since preoperative diagnostics cannot predict tumor histology, combined use is justified for patients with contrast enhancing lesions, optimizing surgical results.