Background Glioblastoma multiforme (GBM) is the most common and most aggressive primary tumor of the brain. After initial therapy and total resection of GBM, 80% to 90% of recurrences occur at the surgical margins. Currently, limited data are available in the literature on the possible use of 68Ga–prostate-specific membrane antigen (PSMA-11) for diagnosis of recurrence in GBM patients. The aim was to assess the feasibility and potential of 68Ga-PSMA-11 PET/CT as a diagnostic procedure in patients with histologically confirmed of GBM and suspected recurrent disease on MRI. Results No radiopharmaceutical-related adverse events were noted. Characterization of recurrent disease with MRI included T2-weighted fast spin-echo images, fluid-attenuated inversion recovery and diffusion-weighted imaging sequences, and gadolinium enhanced T1-weighted images. Visual interpretation of PET showed increased accumulation of 68Ga-PSMA-11 in recurrent lesion detected by T1 contrast enhanced and diffusion-weighted imaging images in all patients with a median SUVmax of the tumor of 6.5 and an SUVmean of 3.5. The median tumor-to-background brain ratio and tumor-to-liver ratio obtained from 68Ga-PSMA-11 PET/CT were 96.7 and 0.8, respectively. Conclusions The extremely low background uptake in normal brain tissue and consequently high tumor-to-brain ratio make 68Ga-PSMA-11 PET/CT highly promising for diagnosis of recurrent disease in GBM patients. Although PSMA expression in recurrent GBM also opens a potential way for targeted peptide therapy with α/β-emitters as well as for prediction of treatment with antiangiogenic agents, the low tumor-to-liver ratio observed in the majority of patients in this study suggests a limited role of radiolabeled PSMA ligands for targeted radionuclide therapy of recurrent GBM.

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Glioblastoma is the most common and malignant primary brain tumour, with a poor prognosis. Introduction of new treatment options is critically important. The study aimed to assess the appropriateness of escalation doses and toxicity of [225Ac]Ac-DOTA-SP therapy. Material and methods A total of 21 patients (age of 43.0 ± 9.5 years), with histologically confirmed recurrent or conversion glioblastoma grade 4 following a standard therapy, have been included in the study. One to 2 intracavitary port-a-cath systems were stereotactically inserted. Patients were treated with escalation dose protocol with 10, 20 and 30 MBq per cycle totally 1–6 doses of [225Ac]Ac-DOTA-SP in 2-month intervals. Therapeutic response was monitored by clinical performance status and MRI imaging. Results Treatment was well tolerated with mostly mild temporary adverse effects (oedema, epileptic seizures, aphasia, hemiparesis) mainly in the group of patients treated with 30 MBq of [225Ac]Ac-DOTA-SP. Only one patient treated with 30 MBq revealed thrombopenia grade 3. There was no other grade 3 and 4 toxicity related to [225Ac]Ac-DOTA-treatment in all groups. The median overall survival time from the primary diagnosis (OS-d) was 35.0 months and from the diagnosis of the recurrence/conversion (OS-r/c) was 13.2 months. From the start of treatment with [225Ac]Ac-DOTA-SP, the median PFS was 2.4 months, and the OS-t was 9.0 months. There were no statistically significant differences between the investigated dose escalation groups. Conclusions Treatment of recurrent glioblastoma with [225Ac]Ac-DOTA-SP is safe and well tolerated up to 30 MBq per cycle. The escalation dose protocol showed good tolerability. Only mild temporary adverse effects were observed. No remarkable haematological, kidney and liver toxicity was seen.

Iron may play important role in neurodegeneration. The results of comparative studies of human brain areas (control and pathological) performed by Mössbauer spectroscopy (MS) and magnetic resonance imaging (MRI) techniques are presented. Mössbauer spectroscopy demonstrated a higher concentration of iron in atypical parkinsonism (progressive supranuclear palsy PSP) in the brain areas Substantia Nigra (SN) and Globus Pallidus (GP) involved in this pathological process, compared to control, while the concentration of iron in pathological tissues in typical parkinsonism (Parkinson's disease -PD) did not differ from that in control. These results were compared with the changes in 1/T1 and 1/T2 (T1 and T2 being the relaxation times determined by MRI). A good linear correlation curve was found between the concentration of iron as determined by MS in different areas of control human brains and between 1/T1 and 1/T2. Whereas the finding in PSP-GP (the brain area involved in PSP) also fitted to such a correlation, this was not so for the correlation between pathological SN -the brain area involved in both diseases -and 1/T2, indicating a dependence of T2 on other factors than just the concentration of iron.

Background: Glioblastoma (GB) is the most malignant primary brain tumor. Therefore, introduction of new treatment options is critically important. The aim of this study was to assess local treatment with α emitters [ 213 Bi]Bi-DOTA-substance P (SP) and [ 225 Ac]Ac-DOTA-SP. Methods: Treatment was performed as salvage therapy in patients with recurrent primary and secondary GB. [ 213 Bi]Bi-DOTA-SP with injected activity 1.85 GBq per cycle was used in 20 primary (48.2 ± 11.8 years old) and in 9 secondary (38.8 ± 10.8 years old) GB patients and [ 225 Ac]Ac-DOTA-SP in 15 primary (45.1 ± 9.9 years old) and in 6 secondary (37.8 ± 6.4 years old) GB patients with a dose escalation scheme (10, 20, and 30 MBq). Results: Local treatment with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP was well tolerated with only few adverse effects. There was no statistically significant difference between [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP groups in survival parameters. For primary GB, survival parameters of patients treated with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP were as follows(in months): progression-free survival time, 2.7 versus 2.4; OS-d (overall survival from time of diagnosis to death from any cause), 23.6 versus 21.0; OS-t (overall survival from the start of treatment to death from any cause), 7.5 versus 5.0; and OS-r (overall survival from recurrence in primary tumors to death from any cause), 10.9 versus 12.0. Survival parameters of secondary GB patients treated with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP were as follows (in months): progression-free survival time, 5.8 versus 2.4; OS-d, 52.3 versus 65.0; OS-t, 16.4 versus 16.0; and OS-c (overall survival from conversion into secondary GB multiforme to death from any cause), 18.4 versus 36.0. Conclusions: The similarity results of 213 Bi or 225 Ac may suggest that the local treatment of brain tumors can be greatly simplified. The experience to date shows that local radioisotope treatment of brain tumors requires further dosimetry studies, taking into account the complexity of biological processes.