Exciton migration in two-dimensional materials

Excitons play an essential role in the optical response of two-dimensional materials. These are bound states showing up in the band gaps of many-body systems and are conceived as quasiparticles formed by an electron and a hole. By performing real-time simulations in hBN, we show that an ultrashort (few-fs) UV pulse can produce a coherent superposition of excitonic states that induces an oscillatory motion of electrons and holes between different valleys in reciprocal space, leading to a sizeable exciton migration in real space. We also show that an ultrafast spectroscopy scheme based on the absorption of an attosecond pulse in combination with the UV pulse can be used to read out the laser-induced coherences, hence to extract the characteristic time for exciton migration. This work opens the door towards ultrafast electronics and valleytronics adding time as a control knob and exploiting electron coherence at the early times of excitation

Uncommon 18F-FDG-PET/CT findings in patients affected by limbic encephalitis: Hyper-hypometabolic pattern with double antibody positivity and migrating foci of hypermetabolism

Autoimmune limbic encephalitis (LE) is a rare disorder; its diagnosis can be challenging.We report two uncommon cases of LE evaluated by brain 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) positron emission tomography/ computed tomography describing themetabolic imaging patterns, which were different from those observed in previous studies: the first one presented an unprecedented 18F-FDG brain mixed pattern, involving also themidbrain, despite negative magnetic resonance imaging exams; the second one showed migrating foci of hypermetabolism, one of which turned into hypometabolism at a later examination

Prevention of dental caries: a review of effective treatments

The objective of this study is to review medical and non medical treatments for prevention of caries. A comprehensive literature search of the most relevant and updated published studies from 01/01/2002 through December 2015 in PubMed/MEDLINE, Embase and Scopus databases regarding the efficacy of strategies and treatments aiming to prevent the development of caries was performed selecting papers on the basis of the Evidence-based Medicine Criteria. We identified thirty systematic reviews on prevention of caries. Analyzing the data the retrieved literature, performance of prevention treatments seems to be high. Prevention treatments may have a relevant impact on the avoiding the development of caries planning

Primary CNS Lymphomas: Challenges in Diagnosis and Monitoring

Primary Central Nervous System Lymphoma (PCNSL) is a rare neoplasm that can involve brain, eye, leptomeninges, and rarely spinal cord. PCNSL lesions most typically enhance homogeneously on T1-weighted magnetic resonance imaging (MRI) and appear T2-hypointense, but high variability in MRI features is commonly encountered. Neurological symptoms and MRI findings may mimic high grade gliomas (HGGs), tumefactive demyelinating lesions (TDLs), or infectious and granulomatous diseases. Advanced MRI techniques (MR diffusion, spectroscopy, and perfusion) and metabolic imaging, such as Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) or amino acid PET (usually employing methionine), may be useful in distinguishing these different entities and monitoring the disease course. Moreover, emerging data suggest a role for cerebrospinal fluid (CSF) markers in predicting prognosis and response to treatments. In this review, we will address the challenges in PCNSL diagnosis, assessment of response to treatments, and evaluation of potential neurotoxicity related to chemotherapy and radiotherapy

Role of PET and SPECT in the study of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis has been defined as a "heterogeneous group of neurodegenerative syndromes characterized by progressive muscle paralysis caused by the degeneration of motor neurons allocated in primary motor cortex, brainstem, and spinal cord." A comprehensive diagnostic workup for ALS usually includes several electrodiagnostic, clinical laboratory and genetic tests. Neuroimaging exams, such as computed tomography, magnetic resonance imaging and spinal cord myelogram, may also be required. Nuclear medicine, with PET and SPECT, may also play a role in the evaluation of patients with ALS, and provide additional information to the clinicians.This paper aims to offer to the reader a comprehensive review of the different radiotracers for the assessment of the metabolism of glucose (FDG), the measurement of cerebral blood flow (CBF), or the evaluation of neurotransmitters, astrocytes, and microglia by means of newer and not yet clinically diffuse radiopharmaceuticals

MRI and 18F-FDG-PET/CT in a rare case of early (precursor) B-lymphoblastic leukaemia with bone involvement as initial manifestation

A 4-year old girl presenting gait difficulty was referred for spine X-ray and Magnetic Resonance Imaging (MRI). MRI showed several diffuse hypointense signals in sacral and lumbar vertebrae. In order to exclude a possible lymphoproliferative disease a 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) was requested. The PET/CT scan confirmed the MRI findings and demonstrated additional findings in the sternum. Therefore, a bone marrow biopsy was performed and a diagnosis of acute lymphoblastic leukaemia — early B type was made

Prediction of 2 years-survival in patients with stage I and II non-small cell lung cancer utilizing (18)F-FDG PET/CT SUV quantification.

BACKGROUND: The purpose of the study was to evaluate the correlation between the maximum standardized uptake value (SUVmax), size of primary lung lesion, disease-free survival (DFS) and overall survival (OS) in patients with stage I and II non-small cell lung cancer (NSCLC) in 2 years follow-up. PATIENTS AND METHODS. Forty-nine patients with stage I–II NSCLC were included in this study. Pre-surgical 2-deoxy-2-[18F]fluoro-D-glucose positron-emission tomography ((18)F-FDG PET/CT) study was performed for all patients. The relationship between SUVmax, tumour size and clinical outcome was measured. The cut-off value for SUVmax and tumour size with the best prognostic significance, probability of DFS and the correlation between SUVmax and the response to therapy were calculated. RESULTS: There was a statistically significant correlation between SUVmax and DFS (p = 0.029). The optimal cut-offs were 9.00 for SUVmax (p = 0.0013) and 30mm for tumour size (p = 0.0028). Patients with SUVmax > 9 and primary lesion size > 30 mm had an expected 2years-DFS of 37.5%, while this rose to 90% if the tumour was <30 mm and/or SUVmax was <9. CONCLUSIONS: In stage I-II, SUVmax and tumour size might be helpful to identify the subgroup of patients with high chance for recurrence

124I-MIBG: a new promising positron-emitting radiopharmaceutical for the evaluation of neuroblastoma

Neuroblastoma is the most common extra-cranial solid tumor in pediatric patients. Despite the established role of 123I-MIBG and 131I-MIBG scintigraphy in this tumor, only limited data are available regarding the use of 124I-metaiodobenzylguanidine (MIBG) positron emission tomography (PET)/computed tomography (CT). We present our preliminary experience with 124I-MIBG PET/CT: two pediatric patients affected by neuroblastoma, who underwent 124I-MIBG PET/CT for pre-therapy distribution evaluation and restaging purposes. We aimed to evaluate whether 124I-MIBG PET/CT can detect as many or more neuroblastoma lesions than 123I/131I-MIBG imaging. Our cases show promising results, although further validation and standardization of 124I-MIBG PET/CT are required