Search results for " MRI"

Investigation of relaxation times of irradiated Fricke gels by means of nuclear magnetic resonance relaxometry

2016

Fricke gel dosimeters are ideal candidates to provide 3D maps of dose distributions and are particularly useful in the plann ing and verification phase of radiotherapy treatments. One of the most effective experimental techniques to reconstruct dose maps is magnetic resonance imaging (MRI). This measures th e nuclear relaxation times variations induced by irradiation. In this work, we analyzed Fricke gels with and without Xylenol Orange by means of a single side-NMR relaxometer (which is abl e to provide information on both relaxation relaxation times T1 and T2 and is mainly used in the field of diagnostics for Cultural Heritage [1-2] to perform porosimetry meaurements). Our goal was to per…

Metodi Automatici per la Compensazione della Distorsione in Immagini di Risonanza Magnetica

A Gabor-based Technique for Bias Removal in MR images

2007

Magnetic Resonance images are often characterized by irregularly displaced luminance fluctuations that are called bias artifact. This disturb is due to a drop in signal intensity caused by the distance between imaged sample and receiver coil. An original approach to bias removal in Magnetic Resonance images is presented, which is based on the use of Gabor filter to extract the artifact. The proposed technique restores the image using a correction model, which is derived from the attenuation of signal diffusion across the tissues. No hypotheses are made about the structure of the tissues under investigation and the used MR spectrum. The approach is presented in detail, and extensive experime…

A Novel Expert System for Non-Invasive Liver Iron Overload Estimation in Thalassemic Patients

2014

Expert Systems can integrate logic based often on computational intelligence methods and they are used in complex problem solving. In this work an Expert System for classifying liver iron concentration in thalassemic patients is presented. In this work, an ANN is used to validate the output of the L.I.O.MO.T (Liver Iron Overload Monitoring in Thalassemia) method against the output of the state-of-the-art method based on MRI T2 assessment for liver iron concentration. The model has been validated with a dataset of 200 samples. The experimental Mean Squared Error results and Correlation show interesting performances. The proposed algorithm has been developed as a plug in for OsiriX Dicom View…

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.

Introducing 1,5 T MRgFUS

2015

MRgFUS is a new noninvasive thermal ablation method, consisting of a high focused ultrasound beam and a MR scanner for imaging and real-time thermal mapping. For decades, therapeutic transcranial ultrasound (tcMRgFUS) was assumed impossible. Novel technology using high-power phased array transducers and multiple channel driving electronics enabled a sharp focal point in the planned target through the intact skull allowing the use of this innovative technology for functional neurosurgery. Preliminary results have been published with systems operating with 3T MR units on patients with neurologic disorders such as essential tremor, tremor dominant idiopathic Parkinson's disease and neuropathic…

Tecnica, indicazioni e risultati trans-cranial MRgFUS

2015

Presentazione prima installazione nazionale di un apparecchiatura tcMRgFUS.

Benign focal lesions

2011

no abstract

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…

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…