Preoperative 11 C-Methionine PET-MRI in Pediatric Infratentorial Tumors.

PURPOSE: MRI is the main imaging modality for pediatric brain tumors, but amino acid PET can provide additional information. Simultaneous PET-MRI acquisition allows to fully assess the tumor and lower the radiation exposure. Although symptomatic posterior fossa tumors are typically resected, the patient management is evolving and will benefit from an improved preoperative tumor characterization. We aimed to explore, in children with newly diagnosed posterior fossa tumor, the complementarity of the information provided by amino acid PET and MRI parameters and the correlation to histopathological results. PATIENTS AND METHODS: Children with a newly diagnosed posterior fossa tumor prospectively underwent a preoperative 11 C-methionine (MET) PET-MRI. Images were assessed visually and semiquantitatively. Using correlation, minimum apparent diffusion coefficient (ADC min ) and contrast enhancement were compared with MET SUV max . The diameter of the enhancing lesions was compared with metabolic tumoral volume. Lesions were classified according to the 2021 World Health Organization (WHO) classification. RESULTS: Ten children were included 4 pilocytic astrocytomas, 2 medulloblastomas, 1 ganglioglioma, 1 central nervous system embryonal tumor, and 1 schwannoma. All lesions showed visually increased MET uptake. A negative moderate correlation was found between ADC min and SUV max values ( r = -0.39). Mean SUV max was 3.8 (range, 3.3-4.2) in WHO grade 4 versus 2.5 (range, 1.7-3.0) in WHO grade 1 lesions. A positive moderate correlation was found between metabolic tumoral volume and diameter values ( r = 0.34). There was no correlation between SUV max and contrast enhancement intensity ( r = -0.15). CONCLUSIONS: Preoperative 11 C-MET PET and MRI could provide complementary information to characterize pediatric infratentorial tumors.

Cluster headache: state of the art of pharmacological treatments and therapeutic perspectives.

Cluster headache (CH) is the most common form of trigeminal autonomic cephalalgia. Current treatments have several limitations, and new drugs are required. This article first briefly reviews present acute and preventive treatments in CH, their mechanism of action and limitations, then describes the state of the art in recent clinical drug trials since 2015, and ends with a critique of trials in the CH field. Research is limited by lack of knowledge of pathophysiology and lack of animal models. In the past 5 years, no brand-new treatment has emerged, but promising drugs, such as CGRP(R) antibodies, are under study. According to the literature and guidelines, clinicians and researchers should be aware of many limitations in study protocols: concomitant medication, patient sample size, patients' protocol compliance, and study designs that tend to restrict patient recruitment.

Binding of the PET radiotracer [¹8F]BF227 does not reflect the presence of alpha-synuclein aggregates in transgenic mice.

Alpha-synuclein (α-syn) aggregation is a neuropathological hallmark of many neurodegenerative diseases, collectively termed synucleinopathies. There is currently no pre-mortem diagnosis tool for these diseases. Although some compounds have been described as potential ligands for α-syn aggregates, no specific PET radiotracer of aggregated α-syn is currently available. Recently, [(18)F]BF227 has been proposed as an α-syn PET radiotracer in the absence of other specific candidates. We proposed here, for the first time, to use this radiotracer in an accelerated mouse model of synucleinopathy presenting α-syn depositions in brainstem and thalamus. Our in vivo and in vitro studies showed that [(18)F]BF227 does not bind to α-syn aggregates. These results highlight the fact that [(18)F]BF227 PET has no suitable characteristics for monitoring this experimental synucleinopathy, justifying the need to develop alternative α-syn PET radiotracers.