68Ga-DOTATOC represents a useful tool in tumor contouring for radiosurgery planning. We present a case series of patients affected by meningiomas on who we performed 68Ga-DOTATOC positron emission tomography (PET)/CT pre-operatively, a subgroup of which also underwent a post-operative 68Ga-DOTATOC PET/CT to evaluate the standardized uptake value (SUV) modification after Gamma Knife ICON treatment in single or hypofractionated fractions. Twenty patients were enrolled/included in this study: ten females and ten males. The median age was 52 years (range 33–80). The median tumor diameter was 3.68 cm (range 0.12–22.26 cm), and the median pre-radiotherapy maximum SUV value was 11 (range 2.3–92). The average of the relative percentage changes between SUVs at baseline and follow up was −6%, ranging from −41% to 56%. The SUV was reduced in seven out of 12 patients (58%), stable in two out of 12 (17%), and increased in three out of 12 (25%), suggesting a biological response of the tumor to the Gamma Knife treatment in most of the cases. 68Ga-DOTATOC-PET represents a valuable tool in assessing the meningioma diagnosis for primary radiosurgery; it is also promising for follow-up assessment.

Background/Aim: We investigated the treatment outcomes and complications associated with hypofractionated GKRS for the treatment of benign and malignant intracranial tumors. Patients and Methods: Patients with intracranial tumors not candidate or refusing surgery were evaluated to assess eligibility to undergo hypofractionated Gamma Knife radiosurgery (GKRS). Targeted volumes were calculated using the GammaPlan ® workstation, and GKRS protocols were delivered with 3 or 5 daily fractions and a maximal total dose of 25 Gy. The thermoplastic mask was used to immobilize the patient's head without pin-based fixation frames. Results: A total of 41 patients, affected with 6 different histologies, were treated and followed-up for a median of 12 months (range=4-24 months). Meningiomas were the most common tumors (33, 80.5%), followed by brain metastases (4, 9.7%). At last follow-up, 33 patients (80.5%) had stable disease, 8 tumor regression (19.5%), and 0 tumor progression. No acute radiation toxicity was observed. Death was reported in 3 patients (7.3%) due to malignant tumor progression. Conclusion: Our hypofractionated GKRS protocol proved to be effective and safe in the treatment of patients with benign and malignant intracranial tumors. Local tumor control was achieved in all patients, with 8 patients showing tumor regression and no cases of acute radiation toxicity.

Background: Several sophisticated techniques and many chemotherapy drugs have improved life expectancy of oncologic patients allowing us to observe late complications which present many years after the initial treatment. Case Description: We present a unique case of a patient affected by acute lymphoblastic leukemia at the age of 6 years, treated with whole brain radiotherapy and intrathecal chemotherapy, developing meningiomatosis and leptomeningeal alterations as late complications and the interaction of these two entities caused a peculiar form of hydrocephalus without ventricular dilation. The diagnosis of pseudotumor cerebri was excluded due the postradio/chemotherapy development of meningiomatosis, not present in a previously head magnetic resonance imaging, that exerted compression to the Sylvian aqueduct causing intracranial hypertension with papillary stasis without ventricles enlargement due to brain stiffness. Moreover, a peculiar intraoperative rubbery consistency of brain parenchyma was detected strengthening this complex diagnosis. Conclusion: At the best of our knowledge, this is the first report of obstructive hydrocephalus without ventricles dilation caused by brain stiffness related to late alterations of oncologic treatments. This report could be a guide for further complex patients diagnoses and for improving treatments efficacy.

Background/Aim: One of the main limitations of standard imaging modalities is microscopic tumor extension, which is often difficult to detect on magnetic resonance imaging (MRI) and computer tomography (CT) in the early stages of the tumor. ( 68)Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide positronemission tomography/computed tomography ( 68 Ga-DOTATOC PET/CT) has shown efficacy in detecting lesions previously undiagnosed by neuroimaging modalities, such as MRI or CT, and has enabled the detection of multiple benign tumors (like multiple meningiomas in a patient presenting with a single lesion on MRI) or additional secondary metastatic locations. Patients and Methods: We retrospectively reviewed data from the Cannizzaro Hospital on brain and body 68 Ga-DOTATOC PET/CT "incidentalomas", defined as tumors missed on CT or MRI scans, but detected on 68 Ga-DOTATOC PET/CT scans. "Incidentalomas" were classified into "brain" and "body" groups based on their location. The standardized uptake values (SUVs) were compared between the two groups. Results: A total of 61 patients with "incidentalomas" documented on the 68 Ga-DOTATOC PET/CT were identified: 18 patients with 25 brain lesions and 43 patients with 85 body lesions. The mean SUV at baseline was 9.01±7.66 in the brain group and 14.8±14.63 in the body group. Conclusion: We present the first series on brain and body "incidentalomas" detected on 68 Ga-DOTATOC PET/CT. Whole-body 68 Ga-DOTATOC PET/CT may be considered in selected patients with brain tumors with high expression of somatostatin receptors to assist radiosurgical or surgical planning and, simultaneously, provide accurate followup with early detection of potential metastases.Somatostatin receptor subtype 2 (SSTR2)-based positron emission tomography (PET), in the form of Gallium-68 DOTA-Phe1-Tyr3-Octreotide ( 68 Ga-DOTATOC), Gallium 68 ( 68 Ga) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate ( 68 Ga-DOTATATE), and 68 Ga-Labeled(1,4,7,10-tetraazacyclododecane-N,N',N'',N'''tetraacetic acid)-1-NaI3-octreotide ( 68 Ga-DOTANOC), has been reported as a useful diagnostic tool in patients with meningiomas, with level II evidence for its use in tumor contouring for radiotherapy planning (1). While planning stereotactic radiosurgery (SRS) for patients with meningiomas, the primary treatment goal is to target all clonogenic tumor cells within the lesion and plan a clinical target volume (CTV), defined as the tumor volume comprising the gross tumor volume (GTV), and subclinical malignant disease (2). However, the main limitation of this technique relates to the 5867

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