11C-Methionine positron emission tomographic imaging of biologic activity of a recurrent glioblastoma treated with stereotaxy-guided laser-induced interstitial thermotherapy.

In patients with recurrent glioblastoma multiforme (GBM), local minimally invasive treatment modalities have gained increasing interest recently because they are associated with fewer side effects than open surgery. For example, local tumor coagulation by laser-induced interstitial thermotherapy (LITT) is such a minimally invasive technique. We monitored the metabolic effects of stereotaxy-guided LITT in a patient with a recurrent GBM using amino acid positron emission tomography (PET). Serial 11C-methyl-L-methionine positron emission tomography (MET-PET) and contrast-enhanced computed tomography (CT) were performed using a hybrid PET/CT system in a patient with recurrent GBM before and after LITT. To monitor the biologic activity of the effects of stereotaxy-guided LITT, a threshold-based volume of interest analysis of the metabolically active tumor volume (MET uptake index of ≥ 1.3) was performed. A continuous decline in metabolically active tumor volume after LITT could be observed. MET-PET seems to be useful for monitoring the short-term therapeutic effects of LITT, especially when patients have been pretreated with a multistep therapeutic regimen. MET-PET seems to be an appropriate tool to monitor and guide experimental LITT regimens and should be studied in a larger patient group to confirm its clinical value.

MR-guided laser-induced interstitial thermotherapy of recurrent glioblastoma multiforme: preliminary results in 16 patients.

We investigated the survival after laser-induced interstitial thermotherapy in 16 patients suffering from recurrent glioblastoma multiforme. The concept underlying the intervention is the cytoreduction of the tumor tissue by local thermocoagulation. All patients received standard chemotherapy (temozolomide). The median overall survival time after the first relapse was 9.4 months, corresponding to a median overall survival time after laser irradiation of 6.9 months. During the study, however, the median survival after laser coagulation increased to 11.2 months. This survival time is substantially longer than those reported for the natural history (<5 months) or after chemotherapy (temozolomide: 5.4-7.1 months). We conclude that cytoreduction by laser irradiation might be a promising option for patients suffering from recurrent glioblastoma multiforme. In addition, the data indicate the presence of a substantial learning curve. Future work should optimize the therapeutic regimen and evaluate this treatment approach in controlled clinical trials.

MR-guided laser irradiation of recurrent glioblastomas.

We treated two patients with recurrent glioblastoma multiforme using Nd:YAG laser irradiation in the framework of a salvage therapy. The underlying concept is to achieve cytoreduction by partial coagulation of the tumor. Magnetic resonance imaging (MRI) follow-up examinations revealed a volume reduction of the laser-irradiated areas, while the untreated parts of the tumor exhibited a progression. The survival time after the diagnosis of the recurrence was 16 and 20 months, respectively, which is substantially (about four times) longer than the natural history of the disease would suggest. In conclusion, cytoreduction by laser irradiation may be a promising option for patients suffering from recurrent glioblastoma multiforme. Future work should optimize the therapeutic regimen and evaluate this treatment approach in controlled clinical trials.