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Marina di Pisa, Italy

Reggiani L.,Polytechnic of Milan | Gola A.,Polytechnic of Milan | Maggio G.M.,Fondazione Bruno Kessler | Tiberi G.,Imago7 Foundation
International Journal of Distributed Sensor Networks | Year: 2015

The proliferation of wireless communications systems poses new challenges in terms of coexistence between heterogeneous devices operating within the same frequency bands. In fact, in case of high-density concentration of wireless devices, like indoor environments, the network performance is typically limited by the mutual interference among the devices themselves, such as for wireless local area networks (WLANs). In this paper, we analyze a protocol strategy for managing multiple access in wireless networks. A network of sensors colocated with the WLAN terminals forms a control layer for managing the medium access and scheduling resources in order to limit collisions and optimize the WLAN data traffic; this control layer is based on a low-power wideband technology characterized by interference robustness, like CDMA (code division multiple access) or UWB (ultra-wideband) for sensors. In this work, we perform an analytical and simulative performance study of the saturated throughput, showing numerical results for the UWB-IR (Impulse Radio) sensors case and highlighting the advantage that can be provided particularly in very high capacity systems, which constitute the necessary evolution of current WLAN versions. © 2015 Luca Reggiani et al.

Frosini D.,University of Pisa | Ceravolo R.,University of Pisa | Tosetti M.,IRCCS | Bonuccelli U.,University of Pisa | And 2 more authors.
Journal of Neural Transmission | Year: 2016

Ten healthy subjects (HS) and 15 patients with atypical parkinsonisms underwent 7-T susceptibility-weighted-imaging MR to evaluate substantia nigra (SN). All HS were judged “normal”. Twelve out of 15 patients exhibited bilateral abnormal SN while three patients with corticobasal degeneration (CBD) showed bilateral normal aspect of SN. Anatomical changes of SN at 7 T occur in multiple system atrophy and progressive supranuclear palsy as previously reported in Parkinson’s disease. Preserved SN in CBD confirms the pathological heterogeneity of this disease. © 2016, Springer-Verlag Wien.

Donatelli G.,Neuroradiology Unit | Costagli M.,Imago7 Foundation | Caldarazzo Ienco E.,University of Pisa | Frosini D.,IRCCS Stella Maris | And 4 more authors.
American Journal of Neuroradiology | Year: 2016

Background and Purpose: Amyotrophic lateral sclerosis is a progressive motor neuron disorder that involves degeneration of both upper and lower motor neurons. In patients with amyotrophic lateral sclerosis, pathologic studies and ex vivo high-resolution MR imaging at ultra-high field strength revealed the co-localization of iron and activated microglia distributed in the deep layers of the primary motor cortex. The aims of the study were to measure the cortical thickness and evaluate the distribution of iron-related signal changes in the primary motor cortex of patients with amyotrophic lateral sclerosis as possible in vivo biomarkers of upper motor neuron impairment. MATERIALS AND METHODS: Twenty-two patients with definite amyotrophic lateral sclerosis and 14 healthy subjects underwent a high-resolution 2D multiecho gradient-recalled sequence targeted on the primary motor cortex by using a 7T scanner. Image analysis consisted of the visual evaluation and quantitative measurement of signal intensity and cortical thickness of the primary motor cortex in patients and controls. Qualitative and quantitative MR imaging parameters were correlated with electrophysiologic and laboratory data and with clinical scores. RESULTS: Ultra-high fieldMRimaging revealed atrophy and signal hypointensity in the deep layers of the primary motor cortex of patients with amyotrophic lateral sclerosis with a diagnostic accuracy of 71%. Signal hypointensity of the deep layers of the primary motor cortex correlated with upper motor neuron impairment (r=-0.47; P <.001) and with disease progression rate (r=-0.60; P =.009). CONCLUSIONS: The combined high spatial resolution and sensitivity to paramagnetic substances of 7T MR imaging demonstrate in vivo signal changes of the cerebral motor cortex that resemble the distribution of activated microglia within the cortex of patients with amyotrophic lateral sclerosis. Cortical thinning and signal hypointensity of the deep layers of the primary motor cortex could constitute a marker of upper motor neuron impairment in patients with amyotrophic lateral sclerosis.

De Ciantis A.,University of Florence | Barkovich A.J.,University of California at San Francisco | Cosottini M.,University of Pisa | Barba C.,University of Florence | And 6 more authors.
American Journal of Neuroradiology | Year: 2015

Background and Purpose: Polymicrogyria is a malformation of cortical development that is often identified in children with epilepsy or delayed development. We investigated in vivo the potential of 7T imaging in characterizing polymicrogyria to determine whether additional features could be identified. Materials and Methods: Ten adult patients with polymicrogyria previously diagnosed by using 3T MR imaging underwent additional imaging at 7T. We assessed polymicrogyria according to topographic pattern, extent, symmetry, and morphology. Additional imaging sequences at 7T included 3D T2∗ susceptibility-weighted angiography and 2D tissue border enhancement FSE inversion recovery. Minimum intensity projections were used to assess the potential of the susceptibility-weighted angiography sequence for depiction of cerebral veins. Results: At 7T, we observed perisylvian polymicrogyria that was bilateral in 6 patients, unilateral in 3, and diffuse in 1. Four of the 6 bilateral abnormalities had been considered unilateral at 3T. While 3T imaging revealed 2 morphologic categories (coarse, delicate), 7T susceptibility-weighted angiography images disclosed a uniform ribbonlike pattern. Susceptibility-weighted angiography revealed numerous dilated superficial veins in all polymicrogyric areas. Tissue border enhancement imaging depicted a hypointense line corresponding to the gray-white interface, providing a high definition of the borders and, thereby, improving detection of the polymicrogyric cortex. Conclusions: 7T imaging reveals more anatomic details of polymicrogyria compared with 3T conventional sequences, with potential implications for diagnosis, genetic studies, and surgical treatment of associated epilepsy. Abnormalities of cortical veins may suggest a role for vascular dysgenesis in pathogenesis. © 2015 AJNR Am J. Neuroradiol.

Tiberi G.,Imago7 Foundation | Costagli M.,Imago7 Foundation | Stara R.,University of Pisa | Cosottini M.,University of Pisa | And 2 more authors.
Journal of Magnetic Resonance | Year: 2013

We present an analytical method for the analysis of Radio Frequency (RF) volume coils for Magnetic Resonance Imaging (MRI), using a 2-D full wave solution with loading by multilayered cylinders. This allows the characterization of radio-frequency E, H, B1, B1+ fields. Comparisons are provided with experimental data obtained at 7.0 T. The procedure permits us to clearly separate the solution to single line source problem (which we call the primordial solution) and the composite solution (i.e. full coil, i.e. the summations of primordial solutions according to the resonator drive configuration). The capability of separating the primordial solution and the composite one is fundamental for a thorough analysis of the phenomena of dielectric resonance, and of standing wave and multi-source interference. We show that dielectric resonance can be identified only by looking at the electromagnetic field from a single line source. © 2013 Elsevier Inc. All rights reserved.

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