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In neurodegenerative diseases, positron emission tomography (PET) imaging plays an important role in the early identification and differential diagnosis in particular in clinically challenging patients. 18F-FDG is still the most widely used and established tracer in this patient group, with different cortical and subcortical regions being preferentially affected in different neurodegenerative diseases, such as frontotemporal dementia, Alzheimer's disease or Lewy Body dementia, resulting in typical hypometabolic patterns. Over the last decades, however, the implementation of tracers specific for the pathological deposits characteristic of the different diseases, such as amyloid and tau, has revolutionized the way of classifying and reporting cases of cognitive impairment of neurodegenerative origin, providing complementary information to 18F-FDG PET. In neuro-oncology, PET imaging can be performed in several clinical indications, as highlighted in the joint European Association of Nuclear Medicine (EANM)/European Association of Neuro-Oncology (EANO)/Response assessment in neuro-oncology (RANO) practice guidelines on imaging in neuro-oncology. For assessment of glioma, amino-acid analogues, such as 11C-methionine or 18F-FET, are used whenever clinically available, as they offer excellent tumor-to-background ratios in malignant tumors. Moreover, dynamic acquisition of amino-acid analogue tracers and assessment of the shape of the time-activity curve can be used to perform noninvasive grading of brain gliomas, differentiating low from high grade presentations. In both settings, however, thorough knowledge of the normal physiological tracer distribution and the variants and pitfalls that can occur during image acquisition, processing and interpretation is mandatory in order to provide optimal diagnostic information to referring physicians and patients. Especially in neuro-oncology, this process can be aided by the active use of coregistered magnetic resonance imaging to accurately identify the imaging correlates of developmental origin, acute and chronic stroke, inflammation, infection and seizure related activity. [ABSTRACT FROM AUTHOR]

Unruptured brain arteriovenous malformations (AVMs) represent a complex disease in young healthy adults. Most often AVMs are clinically silent but also can display a neurologic syndrome due to hypoperfusion/hypometabolism in perilesional brain tissue called steal phenomenon. A 34-year-old woman was admitted to a secondary neurologic center complaining of a right hemiparesis and secondarily generalized seizures. Computed tomography scan and magnetic resonance imaging of the brain showed a left prerolandic AVM without signs of acute or previous bleedings. Digital subtraction angiography confirmed a left juxta-central AVM, with a diffuse pattern, fed by hypertrophic rolandic branches from the left middle cerebral artery. An 18F-fluorodeoxyglucose positron emission tomography-magnetic resonance imaging scan was performed 3 days after the critical episode. A significant hypometabolism in parenchymal regions ipsilaterally to the AVM was detected. Two embolization sessions were performed by means of N-butyl cyanoacrylate glue. At the end of the second procedure, a decrease of the shunt-flow and AVM size was observed. Six months later, 18F-fluorodeoxyglucose positron emission tomography-magnetic resonance imaging scan showed persistent hypometabolism located in the AVM area, with a significant improvement of the cortical hemispheric hypometabolism. The patient was asymptomatic and was sent to stereotactic radiosurgery to complete the treatment. In clinical practice, irritative symptoms in patients with unruptured AVMs could lead to erroneous evaluations. In case of fluctuating clinical syndromes, like our case, establishing that symptoms are related to a steal phenomenon is usually difficult. [ABSTRACT FROM AUTHOR]

Highlights • For each simulated count-statistic level, robust PET features were determined. • About 70% of shape and first-order features resulted robust till 1.2 MBq/kg. • Using Fixed-Bin-Size SUV resampling resulted in a larger number of robust features. • Less relevant impact was observed varying bin size (FBS) and bin number (FBN). • About 45% of textural features were robust till 1.5 MBq/kg for all SUV resamplings. Abstract Purpose The evaluation of features robustness with respect to acquisition and post-processing parameter changes is fundamental for the reliability of radiomics studies. The aim of this study was to investigate the sensitivity of PET radiomic features to acquisition statistics reduction and standardized-uptake-volume (SUV) discretization in PET/MRI pediatric examinations. Methods Twenty-seven lesions were detected from the analysis of twenty-one 18F-FDG-PET/MRI pediatric examinations. By decreasing the count-statistics of the original list-mode data (3 MBq/kg), injected activity reduction was simulated. Two SUV discretization approaches were applied: 1) resampling lesion SUV range into fixed bins numbers (FBN); 2) rounding lesion SUV into fixed bin size (FBS). One hundred and six radiomic features were extracted. Intraclass Correlation Coefficient (ICC), Spearman correlation coefficient and coefficient-of-variation (COV) were calculated to assess feature reproducibility between low tracer activities and full tracer activity feature values. Results More than 70% of Shape and first order features, and around 70% and 40% of textural features, when using FBS and FBN methods respectively, resulted robust till 1.2 MBk/kg. Differences in median features reproducibility (ICC) between FBS and FBN datasets were statistically significant for every activity level independently from bin number/size, with higher values for FBS. Differences in median Spearman coefficient (i.e. patient ranking according to feature values) were not statistically significant, varying the intensity resolution (i.e. bin number/size) for either FBS and FBN methods. Conclusions For each simulated count-statistic level, robust PET radiomic features were determined for pediatric PET/MRI examinations. A larger number of robust features were detected when using FBS methods. [ABSTRACT FROM AUTHOR]

Late-onset primary psychiatric disease (PPD) and behavioral frontotemporal dementia (bvFTD) present with a similar frontal lobe syndrome. We compare brain glucose metabolism in bvFTD and late-onset PPD and investigate the metabolic correlates of cognitive and behavioral disturbances through FDG-PET/MRI. We studied 37 bvFTD and 20 late-onset PPD with a mean clinical follow-up of three years. At baseline evaluation, metabolism of the dorsolateral, ventrolateral, orbitofrontal regions and caudate could classify the patients with a diagnostic accuracy of 91% (95% CI: 0.81–0.98%). 45% of PPD showed low-grade hypometabolism in the anterior cingulate and/or parietal regions. Frontal lobe metabolism was normal in 32% of genetic bvFTD and bvFTD with motor neuron signs. Hypometabolism of the frontal and caudate regions could help in distinguishing bvFTD from PPD, except in cases with motor neuron signs and/or genetic bvFTD for which brain metabolism may be less informative. • Frontal lobe syndrome is shared by late-onset primary psychiatric disease and bvFTD. • Brain glucose metabolism may be mostly useful in the differential diagnosis. • Frontal cortex/caudate metabolism guided a correct classification in 91% of cases. • Sparing of frontal metabolism may be present in bvFTD with MND or genetic bvFTD. • Hypometabolism of parietal cortex may be present in psychiatric diseases. [ABSTRACT FROM AUTHOR]

The aim of the present review was to assess the role of combined 18F-Fluorodeoxyglucose (F-18 FDG) and Ga-68 DOTA-peptides positron emission tomography (PET)-computed tomography (CT) in neuroendocrine tumors (NETs). We have searched MEDLINE databases, including PubMed and Scopus, for studies about the combined FDG and Ga-68 DOTA-peptides PET-CT or PET/Magnetic Resonance Imaging (MRI) in NETs in the last 15 years (from 2004 to November 2019). No limits were applied to the search strategy. Abstracts, reviews, letters to editors, and editorials were excluded. Seven studies met the inclusion criteria. In total 236 patients received both 68Ga-DOTA-peptides and F-18 FDG PET-CT for the characterization of NETs. In particular, 84 patients had a neuroendocrine lung tumor while the others mainly a gastroenteropancreatic NET. The combined use of F-18 FDG and Ga-68 DOTA-peptides (mainly TOC) PET studies provides complementary information regarding different biological characteristics of the lesions, thus enabling a more accurate selection of patients for targeted radionuclide therapy and a better stratification of the prognosis. Ga-68 DOTA-peptides and F-18 FDG PET should be considered complementary in patients with NETs. They should be both performed in the initial staging and during follow-up, with a specific selection of patients and in a multidisciplinary vision. • Ga-68 DOTA-peptides and F-18 FDG PET-CT should be both performed in patients with neuroendocrine tumors. • Ga-68 DOTA-peptides uptake is higher in low-grade NETs, while F-18 FDG PET-CT uptake is high in G2 and G3 NETs. • F-18 FDG should be performed in case of negative or slightly positive Ga-68 DOTA-peptides PET-CT for identification of dedifferentiation status. [ABSTRACT FROM AUTHOR]

Objective To describe a patient with behavioral variant frontotemporal dementia (bvFTD) presenting with impulse control disorders (ICDs) which responded to fluvoxamine and topiramate. Case report A 64-year-old woman was affected by several ICDs. At disease onset, she suffered from impulsive smoking and overeating which caused a body weight increase of 20 kg in 6 months. Later on she manifested binge-eating behavior and skin-picking compulsion. Presence of progressive frontal cognitive impairment (Mini Mental State Examination 24/30) and evidence of hypoperfusion of the anterior cingulate and dorsolateral frontal cortex with brain single-photon emission computed tomography scan contributed to the diagnosis of bvFTD. Use of combination treatment with selective serotonin reuptake inhibitor drugs and topiramate improved all these symptoms. Conclusion This case extends the clinical phenotype of repetitive and compulsive habits in bvFTD to encompass symptoms suggestive of ICDs. It is proposed that fluvoxamine and topiramate may be considered as treatment options in these conditions. [ABSTRACT FROM AUTHOR]

Though the assessment of cognitive functions is proven to be a reliable prognostic indicator in patients with brain tumors, some of these functions, such as cognitive control, are still rarely investigated. The objective of this study was to examine proactive and reactive control functions in patients with focal brain tumors and to identify lesioned brain areas more at "risk" for developing impairment of these functions. To this end, a group of twenty-two patients, candidate to surgery, were tested with an AX-CPT task and a Stroop task, along with a clinical neuropsychological assessment, and their performance was compared to that of a well-matched healthy control group. Although overall accuracy and response times were similar for patients and control groups, the patient group failed more on the BX trials of the AX-CPT task and on the incongruent trials of the Stroop task, specifically. Behavioral results were associated with the damaged brain areas, mostly distributed in right frontal regions, by means of a lesion-symptom mapping multivariate approach. This analysis showed that a white matter cluster in the right prefrontal area was associated with lower d' -context values on the AX-CPT, which reflected the fact that these patients rely more on later information (reactive processes) to respond to unexpected and conflicting stimuli, than on earlier contextual cues (proactive processes). Taken together, these results suggest that patients with brain tumors present an imbalance between proactive and reactive control strategies in high interfering conditions, in association with right prefrontal white matter lesions. • Brain tumor patients show a shift toward the use of reactive control processes. • Right prefrontal lesions are associated with higher reliance on reactive control. • White matter prefrontal cortex plays a role in cognitive control functions. [ABSTRACT FROM AUTHOR]

Abstract: Objective: We describe a patient with prodromal dementia with Lewy bodies (DLB) presenting with drug-induced visual hallucinations (VHs). Case report: A 78-year-old woman complained of daytime recurrent VHs characterized by seeing her face and arms covered in fur and viewing moustaches on her daughter's face. VHs started a few days after the beginning of a combination therapy with duloxetine and lorazepam and ceased within 24 h after their discontinuation. Nonamnestic mild cognitive impairment with profound visual perception deficits and very mild extrapyramidal signs, with abnormal brain DaTscan single photon emission tomography, were present. Three years later, cognitive and neurological follow-up assessments supported the diagnosis of DLB. Conclusion: Perturbation of cerebral serotonergic tone induced by duloxetine, associated with reduced attentional control due to benzodiazepine use, may be the physiopathological substrate of transient VHs in prodromal DLB. [Copyright &y& Elsevier]

Abstract: Semantic dementia (SD) is a neurodegenerative disease belonging to the spectrum of frontotemporal dementia that presents with loss of memory for words and prevalent left temporal pole atrophy. Behavioral disorders, particularly obsessive-compulsive symptoms, are frequent during the course of the disease. We describe a patient presenting with late-onset typical obsessive–compulsive disorder (OCD) that lasted for 10 years as an isolated condition before developing clinical and neuroimaging features of SD. This case alerts clinicians that late-onset OCD may be a psychiatric presentation of a neurodegenerative disorder such as frontotemporal dementia and requires an accurate diagnostic work-up. [Copyright &y& Elsevier]