Objectives: Modern endovascular treatment of unruptured intracranial aneurysms (UIAs) demands for observance of diagnostic reference levels (DRLs). The national DRL (250 Gy cm²) is only defined for coiling. We provide dosimetric data for the following procedures: coiling, flow diverter (FD), Woven EndoBridge (WEB), combined techniques. Methods: A retrospective single-centre study of saccular UIAs treated between 2015 and 2019. Regarding dosimetric analysis, the parameters dose area product (DAP) and fluoroscopy time were investigated for the following variables: endovascular technique, aneurysm location, DSA protocol, aneurysm size, and patient age. Results: Eighty-seven patients (59 females, mean age 54 years) were included. Total mean and median DAP (Gy cm²) were 119 ± 73 (89–149) and 94 (73; 130) for coiling, 128 ± 53 (106–151) and 134 (80; 176) for FD, 128 ± 56 (102–153) and 118 (90; 176) for WEB, and 165 ± 102 (110–219) and 131 (98; 209) for combined techniques (p > .05). Regarding the aneurysm location, neither DAP nor fluoroscopy time was significantly different (p > .05). The lowest and highest fluoroscopy times were recorded for WEB and combined techniques, respectively (median 26 and 94 min; p < .001). A low-dose protocol yielded a 43% reduction of DAP (p < .001). Significantly positive correlations were found between DAP and both aneurysm size (r = .320, p = .003) and patient age (r = .214, p = .046). Conclusions: This UIA study establishes novel local DRLs for modern endovascular techniques such as FD and WEB. A low-dose protocol yielded a significant reduction of radiation dose. Key Points: • This paper establishes local diagnostic reference levels for modern endovascular treatment techniques of unruptured intracranial aneurysms, including flow diverter stenting and Woven EndoBridge device. • Dose area product was not significantly different between endovascular techniques and aneurysm locations, but associated with aneurysm size and patient age. • A low-dose protocol yielded a significant reduction of dose area product and is particularly useful when applying materials with a high radiopacity (e.g. platinum coils).

Background: The treatment of glioblastomas, the most common primary malignant brain tumors, with a devastating survival perspective, remains a major challenge in medicine. Among the recently explored therapeutic approaches, 5-aminolevulinic acid (5-ALA)-mediated interstitial photodynamic therapy (iPDT) has shown promising results. Methods: A total of 16 patients suffering from de novo glioblastomas and undergoing iPDT as their primary treatment were retrospectively analyzed regarding survival and the characteristic tissue regions discernible in the MRI data before treatment and during follow-up. These regions were segmented at different stages and were analyzed, especially regarding their relation to survival. Results: In comparison to the reference cohorts treated with other therapies, the iPDT cohort showed a significantly prolonged progression-free survival (PFS) and overall survival (OS). A total of 10 of 16 patients experienced prolonged OS (≥ 24 months). The dominant prognosis-affecting factor was the MGMT promoter methylation status (methylated: median PFS of 35.7 months and median OS of 43.9 months) (unmethylated: median PFS of 8.3 months and median OS of 15.0 months) (combined: median PFS of 16.4 months and median OS of 28.0 months). Several parameters with a known prognostic relevance to survival after standard treatment were not found to be relevant to this iPDT cohort, such as the necrosis–tumor ratio, tumor volume, and posttreatment contrast enhancement. After iPDT, a characteristic structure (iPDT remnant) appeared in the MRI data in the former tumor area. Conclusions: In this study, iPDT showed its potential as a treatment option for glioblastomas, with a large fraction of patients having prolonged OS. Parameters of prognostic relevance could be derived from the patient characteristics and MRI data, but they may partially need to be interpreted differently compared to the standard of care.

Recently, criteria based on amino acid positron emission tomography (PET) have been proposed for response assessment in diffuse gliomas (PET RANO 1.0). In this study, we compare the prevalence of measurable disease according to PET RANO 1.0 with magnetic resonance imaging (MRI)-based Response Assessment in Neuro-Oncology (RANO) criteria in glioblastoma. We retrospectively identified patients with newly diagnosed IDH-wild-type glioblastoma who underwent [¹⁸F] Fluoroethyltyrosine (FET) PET and MRI after resection or biopsy and before radio-/radiochemotherapy. Two independent investigators analyzed measurable disease according to PET RANO 1.0 or MRI-RANO criteria. Additionally, lesion size, congruency patterns, and uptake intensity on [¹⁸F]FET PET images were assessed. We evaluated 125 patients including 49 cases after primary resection and 76 cases after biopsy. Using PET criteria, 113 out of 125 patients (90.4%) had measurable disease, with a median PET-positive volume of 15.34 cm³ (8.83–38.03). With MRI, a significantly lower proportion of patients had measurable disease (57/125, 45.6%; P < .001) with a median sum of maximum cross-sectional diameters of 35.65 mm (26.18–45.98). None of the 12 patients without measurable disease on PET had measurable disease on MRI. Contrariwise, 56/68 patients (82.4%) without measurable disease on MRI exhibited measurable disease on PET. Clinical performance status correlated significantly with PET-positive volume and MRI-based sum of diameters (P < .0059, P < .0087, respectively). [¹⁸F]FET PET identifies a higher number of patients with measurable disease compared to conventional MRI in newly diagnosed glioblastoma. PET-based assessment may serve as a novel baseline parameter for evaluating residual tumor burden and improving patient stratification in glioblastoma studies. Further validation in prospective trials is warranted.

Background: Single-isocenter dynamic conformal arc (SIDCA) therapy is a technically efficient way of delivering stereotactic radiosurgery (SRS) to multiple metastases simultaneously. This study reports on the safety and feasibility of linear accelerator (LINAC) based SRS with SIDCA for patients with multiple brain metastases. Methods: All patients who received SRS with this technique between November 2017 and June 2019 within a prospective registry trial were included. The patients were irradiated with a dedicated planning tool for multiple brain metastases using a LINAC with a 5 mm multileaf collimator. Follow-up was performed every 3 months, including clinical and radiological examination with cranial magnetic resonance imaging (MRI). These early data were analyzed using descriptive statistics and the Kaplan–Meier method. Results: A total of 65 patients with 254 lesions (range 2–12) were included in this analysis. Median beam-on time was 23 min. The median follow-up at the time of analysis was 13 months (95% CI 11.1–14.9). Median overall survival and median intracranial progression-free survival was 15 months (95% CI 7.7–22.3) and 7 months (95% CI 3.9–10.0), respectively. Intracranial and local control after 1 year was 64.6 and 97.5%, respectively. During follow-up, CTCAE grade I adverse effects (AE) were experienced by 29 patients (44.6%; 18 of them therapy related, 27.7%), CTCAE grade II AEs by four patients (6.2%; one of them therapy related, 1.5%), and CTCAE grade III by three patients (4.6%; none of them therapy related). Two lesions (0.8%) in two patients (3.1%) were histopathologically proven to be radiation necrosis. Conclusion: Simultaneous SRS using SIDCA seems to be a feasible and safe treatment for patients with multiple brain metastases.