Altered spread of waves of activities at large scale is influenced by cortical thickness organization in temporal lobe epilepsy: a magnetic resonance imaging-high-density electroencephalography study.

Temporal lobe epilepsy is a brain network disorder characterized by alterations at both the structural and the functional levels. It remains unclear how structure and function are related and whether this has any clinical relevance. In the present work, we adopted a novel methodological approach investigating how network structural features influence the large-scale dynamics. The functional network was defined by the spatio-temporal spreading of aperiodic bursts of activations (neuronal avalanches), as observed utilizing high-density electroencephalography in patients with temporal lobe epilepsy. The structural network was modelled as the region-based thickness covariance. Loosely speaking, we quantified the similarity of the cortical thickness of any two brain regions, both across groups and at the individual level, the latter utilizing a novel approach to define the subject-wise structural covariance network. In order to compare the structural and functional networks (at the nodal level), we studied the correlation between the probability that a wave of activity would propagate from a source to a target region and the similarity of the source region thickness as compared with other target brain regions. Building on the recent evidence that large-waves of activities pathologically spread through the epileptogenic network in temporal lobe epilepsy, also during resting state, we hypothesize that the structural cortical organization might influence such altered spatio-temporal dynamics. We observed a stable cluster of structure-function correlation in the bilateral limbic areas across subjects, highlighting group-specific features for left, right and bilateral temporal epilepsy. The involvement of contralateral areas was observed in unilateral temporal lobe epilepsy. We showed that in temporal lobe epilepsy, alterations of structural and functional networks pair in the regions where seizures propagate and are linked to disease severity. In this study, we leveraged on a well-defined model of neurological disease and pushed forward personalization approaches potentially useful in clinical practice. Finally, the methods developed here could be exploited to investigate the relationship between structure-function networks at subject level in other neurological conditions.

Altered spreading of neuronal avalanches in temporal lobe epilepsy relates to cognitive performance: A resting-state hdEEG study.

OBJECTIVE: Large aperiodic bursts of activations named neuronal avalanches have been used to characterize whole-brain activity, as their presence typically relates to optimal dynamics. Epilepsy is characterized by alterations in large-scale brain network dynamics. Here we exploited neuronal avalanches to characterize differences in electroencephalography (EEG) basal activity, free from seizures and/or interictal spikes, between patients with temporal lobe epilepsy (TLE) and matched controls. METHOD: We defined neuronal avalanches as starting when the z-scored source-reconstructed EEG signals crossed a specific threshold in any region and ending when all regions returned to baseline. This technique avoids data manipulation or assumptions of signal stationarity, focusing on the aperiodic, scale-free components of the signals. We computed individual avalanche transition matrices to track the probability of avalanche spreading across any two regions, compared them between patients and controls, and related them to memory performance in patients. RESULTS: We observed a robust topography of significant edges clustering in regions functionally and structurally relevant for the TLE, such as the entorhinal cortex, the inferior parietal and fusiform area, the inferior temporal gyrus, and the anterior cingulate cortex. We detected a significant correlation between the centrality of the entorhinal cortex in the transition matrix and the long-term memory performance (delay recall Rey-Osterrieth Complex Figure Test). SIGNIFICANCE: Our results show that the propagation patterns of large-scale neuronal avalanches are altered in TLE during the resting state, suggesting a potential diagnostic application in epilepsy. Furthermore, the relationship between specific patterns of propagation and memory performance support the neurophysiological relevance of neuronal avalanches.

Non-traumatic Myositis Ossificans as Unusual Cause of Neck Pain During COVID-19 Pandemic: a Case Report.

Myositis ossificans circumscripta (MOC) is a benign disease characterized by localized heterotopic bone formation within muscles or soft tissue, usually interesting great muscles of extremities. We report a rare case of unusual location in the neck not associated with previous trauma, mimicking a solid tumor, with well-documented diagnostic imaging features. During COVID-19 pandemic outbreak in Italy, in May 2020, a 14-year-old boy developed a progressive and persistent neck pain on the right side, without known history of trauma. Initial therapy with non-steroid anti-inflammatory drugs and physiokinetic therapy gave only a slight improvement. A neck ultrasound showed an inhomogeneous right neck mass, with posterior shadowing due to calcifications. Computed tomography and magnetic resonance imaging confirmed a huge right neck mass, located in the paravertebral space with peripheral calcifications and mild central contrast enhancement. After surgical excision of the lesion, pathology revealed the presence of muscular tissue mixed with fibroblastic/myofibroblastic proliferation and ossification areas consistent with myositis ossificans. A careful analysis of clinical and radiological features is very important to manage young patients showing progressive pain and swelling of the neck, since MOC can mimic soft tissue or bone tumors, and it should be suspected even in the absence of a known history of trauma.

Modification of MRI pattern of high-grade glioma pseudoprogression in regorafenib therapy.

Pseudoprogression (PP) is a diagnostic dilemma in the follow-up of brain high grade gliomas (HGG), and the introduction of new therapies has further complicated its identification in Magnetic Resonance Imaging (MRI). We report a case of pseudoprogression after intraoperative radiotherapy (ioRT) and Regorafenib therapy in a patient with anaplastic astrocytoma recurrence. A 65-year-old man, treated in August 2017 for a right frontal anaplastic astrocytoma, with surgical resection and following radiotherapy and Temozolomide, in October 2019 was again treated for peri-surgical bed recurrence with resection and ioRT followed by Regorafenib therapy, interrupted in February 2020, after the onset of adverse reactions. MRI examination showed a large irregular alteration posterior to the surgical bed, T2 weighted hypointense featuring strong diffusion restriction (low ADC values), with an irregular contrast-enhancement (CE) pattern, and surrounded by a vast vasogenic oedema; Dynamic Susceptibility Contrast (DSC) perfusion imaging (PWI) showed no increase of relative cerebral blood volume (rCBV). Particularly, lesion appeared markedly hypointense and dusty-like on susceptibility weighted images (SWI) probably due to a constant hemorrhagic diapedesis promoted by Regorafenib. Therefore, pseudoprogression was suspected. Follow-up MRI exams showed gradual reduction of SWI and CE abnormalities, but a persistent DWI restriction. Unfortunately, the last MRI control showed a secondary cerebellar localisation of the disease. New therapies are changing MRI pattern in HGG imaging and this case underlines how a multimodality approach is increasingly necessary. In particular, when using anti-VEGF drugs, SWI can have a crucial role in identifying therapy-related haemorrhagic changes.

Optical read-out of Coulomb staircases in a moiré superlattice via trapped interlayer trions.

Moiré patterns with a superlattice potential can be formed by vertically stacking two layered materials with a relative twist or lattice constant mismatch. In transition metal dichalcogenide-based systems, the moiré potential landscape can trap interlayer excitons (IXs) at specific atomic registries. Here, we report that spatially isolated trapped IXs in a molybdenum diselenide/tungsten diselenide heterobilayer device provide a sensitive optical probe of carrier filling in their immediate environment. By mapping the spatial positions of individual trapped IXs, we are able to spectrally track the emitters as the moiré lattice is filled with excess carriers. Upon initial doping of the heterobilayer, neutral trapped IXs form charged IXs (IX trions) uniformly with a binding energy of ~7 meV. Upon further doping, the empty superlattice sites sequentially fill, creating a Coulomb staircase: stepwise changes in the IX trion emission energy due to Coulomb interactions with carriers at nearest-neighbour moiré sites. This non-invasive, highly local technique can complement transport and non-local optical sensing techniques to characterize Coulomb interaction energies, visualize charge correlated states, or probe local disorder in a moiré superlattice.

Isolated cerebellar progressive multifocal leukoencephalopathy after allogeneic bone marrow transplantation: focus on imaging.

INTRODUCTION: Progressive multifocal leukoencephalopathy (PML) is caused by JC virus opportunistic infection in the setting of immunodeficiency. Typical imaging features are multifocal and asymmetric lesions within supratentorial subcortical white matter in parieto-occipital regions. CASE DESCRIPTION: A 47-year-old patient experienced a relapse of acute myeloid leukemia 21 months after hematopoietic stem cell transplantation. He also had visual impairment and magnetic resonance imaging showed an isolated cerebellar lesion without mass effect or enhancement. Common opportunistic infections and leukemic central nervous system involvement were excluded by cerebrospinal fluid (CSF) analysis. Given the worsening clinical and radiologic scenario, PML was suspected, and CSF protein chain reaction analysis was positive for JC virus. CONCLUSIONS: Given its potential curability, PML should be thoroughly investigated in patients with hematologic neoplasms and atypical isolated cerebellar presentation.

The ONETEP linear-scaling density functional theory program.

We present an overview of the onetep program for linear-scaling density functional theory (DFT) calculations with large basis set (plane-wave) accuracy on parallel computers. The DFT energy is computed from the density matrix, which is constructed from spatially localized orbitals we call Non-orthogonal Generalized Wannier Functions (NGWFs), expressed in terms of periodic sinc (psinc) functions. During the calculation, both the density matrix and the NGWFs are optimized with localization constraints. By taking advantage of localization, onetep is able to perform calculations including thousands of atoms with computational effort, which scales linearly with the number or atoms. The code has a large and diverse range of capabilities, explored in this paper, including different boundary conditions, various exchange-correlation functionals (with and without exact exchange), finite electronic temperature methods for metallic systems, methods for strongly correlated systems, molecular dynamics, vibrational calculations, time-dependent DFT, electronic transport, core loss spectroscopy, implicit solvation, quantum mechanical (QM)/molecular mechanical and QM-in-QM embedding, density of states calculations, distributed multipole analysis, and methods for partitioning charges and interactions between fragments. Calculations with onetep provide unique insights into large and complex systems that require an accurate atomic-level description, ranging from biomolecular to chemical, to materials, and to physical problems, as we show with a small selection of illustrative examples. onetep has always aimed to be at the cutting edge of method and software developments, and it serves as a platform for developing new methods of electronic structure simulation. We therefore conclude by describing some of the challenges and directions for its future developments and applications.

Spinal 'flip-flop' effect in anorexia nervosa: A case report.

Anorexia nervosa is a psychiatric eating disorder related to malnutrition and consequent altered metabolism. A 48-year-old female with a history of anorexia in the last 2 years referred to our hospital with spinal pain. She underwent spinal X-ray and magnetic resonance imaging (MRI) showing multiple vertebral collapses in dorsal and lumbar spine with inversion of normal bone marrow and soft tissue signal in T1-weighted and STIR images. We describe this case of spinal 'flip-flop' phenomenon, underlining how what seems a technical failure is actually a specific imaging pattern related to the clinical context.

Pediatric encephalic ultrasonography: the essentials.

Nowadays, cranial ultrasonography (US) of the newborn represents the first imaging method in brain damage study and its possible outcomes. This exam is performed using the natural fontanelles, especially the anterior one. It is fast, non-invasive and does not produce any side effect. Ultrasonographic examination is usually performed in cases of prematurity, especially in children with birth weight less than 1500 g, because important informations about the possible presence of pathologies such as cerebral hemorrhage and hypoxic-ischemic encephalopathy are given. This approach can be useful also in the study of pre- and post-natal infections, for example, type II Herpes Simplex virus or Cytomegalovirus infections, or pointing out vascular malformations such as vein of Galen aneurysm. Although less important than methods such as computed tomography (CT) and magnetic resonance imaging (MRI) in the evaluation of trauma and tumors, ultrasound can provide useful informations or be used in first instance in the suspicion of a brain mass.

Wannier90 as a community code: new features and applications.

Wannier90 is an open-source computer program for calculating maximally-localised Wannier functions (MLWFs) from a set of Bloch states. It is interfaced to many widely used electronic-structure codes thanks to its independence from the basis sets representing these Bloch states. In the past few years the development of Wannier90 has transitioned to a community-driven model; this has resulted in a number of new developments that have been recently released in Wannier90 v3.0. In this article we describe these new functionalities, that include the implementation of new features for wannierisation and disentanglement (symmetry-adapted Wannier functions, selectively-localised Wannier functions, selected columns of the density matrix) and the ability to calculate new properties (shift currents and Berry-curvature dipole, and a new interface to many-body perturbation theory); performance improvements, including parallelisation of the core code; enhancements in functionality (support for spinor-valued Wannier functions, more accurate methods to interpolate quantities in the Brillouin zone); improved usability (improved plotting routines, integration with high-throughput automation frameworks), as well as the implementation of modern software engineering practices (unit testing, continuous integration, and automatic source-code documentation). These new features, capabilities, and code development model aim to further sustain and expand the community uptake and range of applicability, that nowadays spans complex and accurate dielectric, electronic, magnetic, optical, topological and transport properties of materials.

Granular cell tumor of the breast: a multidisciplinary challenge.

Granular cell tumors are rare soft tissue tumors; they are almost never malignant, but can mimic a carcinoma clinically, radiologically and microscopically. The finding of a suspicious lump often entails subsequent diagnostic procedures that can pose significant anxiety on patients before reaching a challenging differential diagnosis. The physical and psychological burden is even more significant when such findings occur during the follow up of a previous oncologic condition. Sometimes the fear for a potential local or distant recurrence can be responsible for a misdiagnosis and lead to patient overtreatment.

Pediatric ultrasonography of the pancreas: normal and abnormal findings.

The pancreas is easily investigated in children thanks to the relative lack of fat tissue and the large left hepatic lobe with an optimal acoustic window. The use of high frequency, even linear transducers, usually results in detailed images of all pancreatic areas. A wide spectrum of pancreatic pathologic conditions can be identified and monitored at ultrasound although they are relatively uncommon during childhood compared to the adult. In this paper we briefly review the anatomy, technique, and sonographic aspects of normal and pathological pediatric pancreas.

Diagnostic imaging features of necrotizing enterocolitis: a narrative review.

Necrotizing enterocolitis (NEC) is an inflammatory process, characterized by intestinal necrosis of variable extension, leading to perforation, generalized peritonitis and death. The classical pathogenetic theory focuses on mucosal damage related to a stress induced intestinal ischemia leading to mucosal injury and bacterial colonization of the wall. A more recent hypothesis emphasizes the role of immaturity of gastrointestinal and immune system, particularly of the premature, responsible of bowel wall vulnerability and suffering. NEC is the most common gastrointestinal emergency in the newborn, with a higher incidence in the preterm; improvement of neonatal resuscitation techniques enables the survival of premature of very low birth weight (VLBW) with prolongation of hospital stay for perinatal and neonatal care and a higher risk of NEC. Clinical presentation of NEC in newborn ranges from mild forms with moderate gastrointestinal tract disorder and that can heal spontaneously, to very serious forms with fulminant course characterized by perforation, peritonitis, sepsis, disseminated intravascular coagulation (DIC) and shock. Imaging modality in the diagnosis of NEC is historically represented by the plain-film abdominal radiographs which can be performed every 6 hours because of the rapid evolution that may occur in the patient's clinical condition. However ultrasound (US), in recent years, is playing an increasingly important role in the evaluation of early stages of the disease as it provides images in real time of the abdominal structures being able to assess the presence and validity of peristalsis of the bowel loops, detect the thickness of the intestinal wall and the presence of minimal amounts of fluid in the peritoneal cavity. In this paper we review the pathogenesis, clinical presentation and imaging of NEC with a particular attention to the emergent role of US in the diagnosis of the disease.

Contrast-enhanced MR Imaging versus Contrast-enhanced US: A Comparison in Glioblastoma Surgery by Using Intraoperative Fusion Imaging.

Purpose To compare contrast material enhancement of glioblastoma multiforme (GBM) with intraoperative contrast-enhanced ultrasonography (US) versus that with preoperative gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging by using real-time fusion imaging. Materials and Methods Ten patients with GBM were retrospectively identified by using routinely collected, anonymized data. Navigated contrast-enhanced US was performed after intravenous administration of contrast material before tumor resection. All patients underwent tumor excision with navigated intraoperative US guidance with use of fusion imaging between real-time intraoperative US and preoperative MR imaging. With use of fusion imaging, glioblastoma contrast enhancement at contrast-enhanced US (regarding location, morphologic features, margins, dimensions, and pattern) was compared with that at gadolinium-enhanced T1-weighted MR imaging. Results Fusion imaging for virtual navigation enabled matching of real-time contrast-enhanced US scans to corresponding coplanar preoperative gadolinium-enhanced T1-weighted MR images in all cases, with a positional discrepancy of less than 2 mm. Contrast enhancement of gadolinium-enhanced T1-weighted MR imaging and contrast-enhanced US was superimposable in all cases with regard to location, margins, dimensions, and morphologic features. The qualitative analysis of contrast enhancement pattern demonstrated a similar distribution in contrast-enhanced US and gadolinium-enhanced T1-weighted MR imaging in nine patients: Seven lesions showed peripheral inhomogeneous ring enhancement, and two lesions showed a prevalent nodular pattern. In one patient, the contrast enhancement pattern differed between the two modalities: Contrast-enhanced US showed enhancement of the entire bulk of the tumor, whereas gadolinium-enhanced T1-weighted MR imaging demonstrated peripheral contrast enhancement. Conclusion Glioblastoma contrast enhancement with contrast-enhanced US is superimposable on that provided with preoperative gadolinium-enhanced T1-weighted MR imaging regarding location, margins, morphologic features, and dimensions, with a similar enhancement pattern in most cases. Thus, contrast-enhanced US is of potential use in the surgical management of GBM. © RSNA, 2017 Online supplemental material is available for this article.

Performance of extended Lagrangian schemes for molecular dynamics simulations with classical polarizable force fields and density functional theory.

Iterative energy minimization with the aim of achieving self-consistency is a common feature of Born-Oppenheimer molecular dynamics (BOMD) and classical molecular dynamics with polarizable force fields. In the former, the electronic degrees of freedom are optimized, while the latter often involves an iterative determination of induced point dipoles. The computational effort of the self-consistency procedure can be reduced by re-using converged solutions from previous time steps. However, this must be done carefully, as not to break time-reversal symmetry, which negatively impacts energy conservation. Self-consistent schemes based on the extended Lagrangian formalism, where the initial guesses for the optimized quantities are treated as auxiliary degrees of freedom, constitute one elegant solution. We report on the performance of two integration schemes with the same underlying extended Lagrangian structure, which we both employ in two radically distinct regimes-in classical molecular dynamics simulations with the AMOEBA polarizable force field and in BOMD simulations with the Onetep linear-scaling density functional theory (LS-DFT) approach. Both integration schemes are found to offer significant improvements over the standard (unpropagated) molecular dynamics formulation in both the classical and LS-DFT regimes.

Hirayama's disease: an Italian single center experience and review of the literature.

BACKGROUND: Hirayama's disease (HD), is a benign, self-limited, motor neuron disease, characterized by asymmetric weakness and atrophy of one or both distal upper extremities. In the present study we report the clinical, electrophysiological and MRI features of a group of Italian patients, with review of the literature. Moreover we propose an optimized MRI protocol for patients with suspected or diagnosed HD in order to make an early diagnosis and a standardized follow up. METHODS: Eight patients with clinical suspicion of Hirayama disease underwent evaluation between January 2007 and November 2013. All patients underwent standard nerve conduction studies (NCS), electromyography (EMG) and motor/sensory evoked potentials (MEP/SEP). Cervical spine MRI studies were conducted with a 1.5 Tesla MRI scanner in neutral and flexion position, including sagittal T1-weighted sequences and sagittal and axial T2-weighted sequences. The following diagnostic features were evaluated: abnormal cervical curvature, localized cervical cord atrophy in the lower tract (C4-C7), presence of cord flattening (CF), intramedullary signal hyperintensity on T2 weighted sequences, anterior shifting of the posterior wall of the cervical dural sac (ASD) and presence of flow voids (EFV) in the posterior epidural space during flexion. RESULTS: All patients complained of weakness in hand muscles as initial symptoms, associated with hand tremor in three of them and abnormal sweating of the hand palm in two of them. No sensory deficits and weakness at lower limbs were reported by any patients. Distal deep tendon reflexes at upper limbs were absent in all patients with the absence of the right tricipital reflex in one of them. Deep tendon reflexes at lower limbs were normal and no signs of pyramidal tract involvement were present. The clinical involvement at onset was unilateral in six patients (three left-sided and three right-sided) and bilateral asymmetric in two of them, with the right side more affected. With the progression of the disease all patients but one experienced weakness and wasting of hand muscles and forearm bilaterally, but still asymmetric. The duration of the progression phase of the disease ranged from eight months to three years. In all patients, NCS and EMG findings were consistent with a spinal metameric disorder involving the C7-T1 myotomes bilaterally; sensory conduction and electrophysiologic features at lower limbs were normal. MEP and SEP were normal and we did not observe the disappearance of the spinal potential during the neck flexion in any of the patients. MRI is the best diagnostic tool in the diagnosis of HD; it can confirm clinical diagnosis and exclude other conditions responsible for the neurological deficits leading to a correct patient management and therapy, limiting arm impairment. On MRI all patients had loss of the normal cervical lordosis (100%). Five patients had loss of attachment of posterior dural sac and anterior dural shift on flexion MRI with presence of flow voids from venous plexus congestion (62.5%); three patients had no anterior dislocation of the dural sac and no epidural vein congestion. Two patients showed localized cord atrophy, one at C5-C6 and the other at C6-C7 level (25%). Three patients had T2 intramedullary hyperintensities (37.5%) and cord flattening (CF) was present in 5 patients of 8 (62.5%). CONCLUSIONS: HD is a rare entity and a self-limited condition, but it has to be early differentiated from other diseases that may determine myelopathy and amyotrophy to establish a correct therapy and limit arm impairment. MRI is very important to confirm the clinical suspect of HD and a standardized MRI protocol using axial and sagittal images in both neutral and flexing position is needed, in order to diagnose and follow up affected patients.

Giant colon polyp in a child with suspected inflammatory bowel disease: US findings.

A 6-year-old boy with a history of diarrhea and rectal bleeding was referred to our department where he underwent ultrasound (US) examination for suspected inflammatory bowel disease. US showed the presence of an echoic oval mass measuring about 30 × 24 mm located at the transition between the transverse and descending colon. It moved with the peristaltic waves and was attached to the intestinal wall through a pedicle. Color Doppler showed intralesional blood flow. On the basis of these findings, the patient was suspected of having a colon polyp. This diagnosis was confirmed at subsequent colonoscopy. The mass was removed using a diathermy snare, and histologic examination revealed hamartomatous polyp measuring 32 mm.

Anharmonic Infrared Spectroscopy through the Fourier Transform of Time Correlation Function Formalism in ONETEP.

Density functional theory molecular dynamics (DFT-MD) provides an efficient framework for accurately computing several types of spectra. The major benefit of DFT-MD approaches lies in the ability to naturally take into account the effects of temperature and anharmonicity, without having to introduce any ad hoc or a posteriori corrections. Consequently, computational spectroscopy based on DFT-MD approaches plays a pivotal role in the understanding and assignment of experimental peaks and bands at finite temperature, particularly in the case of floppy molecules. Linear-scaling DFT methods can be used to study large and complex systems, such as peptides, DNA strands, amorphous solids, and molecules in solution. Here, we present the implementation of DFT-MD IR spectroscopy in the ONETEP linear-scaling code. In addition, two methods for partitioning the dipole moment within the ONETEP framework are presented. Dipole moment partitioning allows us to compute spectra of molecules in solution, which fully include the effects of the solvent, while at the same time removing the solvent contribution from the spectra.