Search results for "MRI."
showing 10 items of 591 documents
Noise Filtering Using Edge-Driven Adaptive Anisotropic Diffusion
2008
This paper presents a method aimed to noise removal in MRI (Magnetic Resonance Imaging). We propose an improvement of Perona and Malik's anisotropic diffusion filter. In our schema, the diffusion equation of the filter has been modified to take into account the edges direction, This allows the filter to blur uniform areas, while it better preserves the edges. Both quantitative and qualitative evaluation is presented and the results are compared with other methods.
Morphological exponential entropy driven-HUM.
2006
This paper presents an improvement to the Ex- ponential Entropy Driven - Homomorphic Unsharp Masking (E 2 D − HUM ) algorithm devoted to illumination artifact sup- pression on Magnetic Resonance Images. E 2 D−HUM requires a segmentation step to remove dark regions in the foreground whose intensity is comparable with background, because strong edges produce streak artifacts on the tissues. This new version of the algorithm keeps the same good properties of E 2 D − HUM without a segmentation phase, whose parameters should be chosen in relation to the image. I. INTRODUCTION Most of the studies on illumination correction found in literature are oriented to brain (18) magnetic resonance images (…
Is there still a role for lesioning in functional neurosurgery: the Italian experience of delivering focused ultrasound high energy through a 1,5 tes…
2017
DCE and DSC perfusion MRI acquisition: diagnostic accuracy during the follow-up of the primary and metastatic intra-axial brain tumors treated by Ste…
Distinguishing radiation necrosis from tumor recurrence and tumor progression is crucial for the evaluation of treatment response and treatment planning. The appearance of treatment-induced tissue necrosis on conventional Magnetic Resonance Imaging (MRI) are very similar to brain tumor recurrence and it could be difficult to differentiate the two entities during the follow-up MRI examinations. Dynamic Susceptibility Contrast-enhanced (DSC) and Dynamic Contrast-Enhanced (DCE) are the MRI perfusion techniques using an exogenous, intravascular, no diffusible gadolinium-based contrast agent. The aim of this study is to compare the diagnostic accuracy of DSC and DCE perfusion MRI in the differen…
MRI Characterization of non-Gaussian water diffusion in the brain using Diffusion Kurtosis Imaging (DKI)
2016
Diffusion tensor imaging (DTI) is the most commonly used technique to extract microstructural features from a set of diffusion-weighted images. In addition to the metrics obtained with DTI, diffusion kurtosis imaging (DKI) can provide non-Gaussian diffusion measures by means of the kurtosis tensor. DKI give an dimensionless measure that quantifies the deviation of the water diffusion displacement profile from the Gaussian distribution of unrestricted diffusion, providing a measure of the degree of diffusion hindrance or restriction. DKI has shown to be more sensitive to tissue microstructural changes in both normal and pathological neural tissue. The aim of this work is the description of t…
Functional connectivity modulation induced by transcranial direct current stimulation of the motor network: a Resting-State fMRI study
2016
Resting-state functional connectivity represents a novel fMRI approach that allows detection of temporal correlations in spontaneous BOLD signal oscillations while subjects rest quietly in the scanner. Functional connectivity (FC) can be defined as the synchrony of neural activity among spatially distant regions. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is known to modulate cortical activity and FC among brain regions. This study is aimed at measuring the variation of functional connectivity between cortical brain regions after tDCS along time. The temporal concatenation group ICA showed that immediately after anodal stimulation the a…
IMAGING OF VESTIBULAR SCHWANNOMA [Chapter 4]
2020
Lesions of the cerebellopontine angle and internal auditory canal are a frequent finding in neuroradiological examinations and their detection may represent a diagnostic challenge. Among these lesions, vestibular schwannomas and meningiomas are certainly the most frequent and account for up to 90% of all cerebellopontine angle tumours. The remaining ones are a group of lesions arising from the different structures found in these anatomical regions such as haemangiomas, lipomas, lymphomas, facial nerve tumours, and aneurysms. This chapter will introduce this topic focusing on a practical coverage of the typical and atypical neuroradiological signs that will drive towards the most correct dif…
DESCRIZIONE DI UN CASO DI LESIONE REVERSIBILE DELLO SPLENIO DEL CORPO CALLOSO IN PAZIENTE CON MONONUCLEOSI INFETTIVA DA COINFEZIONE EPSTEIN-BARR VIRU…
2013
SCOPO Presentiamo un caso di encefalite virale con lesione reversibile dello splenio del corpo calloso (SCC) in un ragazzo di 16 anni con mononucleosi infettiva da coinfezione Epstein-Barr Virus (EBV) e Citomegalovirus (CMV). MATERIALI E METODI Il paziente, a causa della comparsa improvvisa di stato confusionale, irrigidimento e movimenti involontari alternati a tremori in corso di mononucleosi infettiva, giungeva in PS, dove eseguiva una TC encefalo (Siemens SOMATOM Definition AS+ - 128 strati) in condizioni di base ed in tecnica sequenziale, che non evidenziava reperti significativi. Veniva quindi ricoverato con il sospetto di encefalite virale e, il giorno successivo, veniva sottoposto a…
Presacral Myelolipoma
2014
Many reports have described adrenal myelolipomas but there have been only a few reports of extra-adrenal myelolipomas. We describe a 74-year-old woman who came to our observa- tion for MRI of the lumbar spine for typical lumbar back pain. In addition to signs of mild scoliosis and spondylo disc arthrosis, MR imaging revealed a presacral mass showing a heterogeneously high signal in all pulse sequences and almost completely suppressed on inversion recovery sequences for fat tissue. CT imaging confirmed the fatty nature of the lesion and no signs of bone involvement. These findings were most consistent with a diagnosis of a rare presacral myelolipoma as confirmed at histopathologic analysis. …
«Com’è un mafioso?» Raccontare dall’interno il “mestiere” del poliziotto
2018
Il saggio analizza il racconto autobiografico che Maurizio Ortolan, (ispettore di polizia in servizio dal 1987 al 2013 presso il Nucleo centrale anticrimine) fa della sua esperienza lavorativa, con taglio asciutto ed essenziale, denso di rimandi a importanti episodi delle cronache criminali italiane degli ultimi trent’anni e carico di un vissuto che ha incrociato le biografie di alcuni dei più significativi protagonisti di quel periodo. Utilizzando uno sguardo etnografico e partendo dal racconto di Ortolan, l'autrice fa emergere quegli aspetti che, pur strettamente legati al singolo vissuto, gettano luce sulle pratiche condivise del "mestiere" del poliziotto.