Search results for "MRI."

Ventricular arrhythmias in children: the uselessness of MRI.

2009

Data-driven analysis of simultaneous EEG/fMRI reveals neurophysiological phenotypes of impulse control

2016

Response inhibition is the ability to suppress inadequate but prepotent or ongoing response tendencies. A fronto-striatal network is involved in these processes. Between-subject differences in the intra-individual variability have been suggested to constitute a key to pathological processes underlying impulse control disorders. Single-trial EEG/fMRI analysis allows to increase sensitivity for inter-individual differences by incorporating intra-individual variability. Thirty-eight healthy subjects performed a visual Go/Nogo task during simultaneous EEG/fMRI. Of 38 healthy subjects, 21 subjects reliably showed Nogo-related ICs (Nogo-IC-positive) while 17 subjects (Nogo-IC-negative) did not. C…

Fronto-parietal homotopy in resting-state functional connectivity predicts task-switching performance

2021

Homotopic functional connectivity reflects the degree of synchrony in spontaneous activity between homologous voxels in the two hemispheres. Previous studies have associated increased brain homotopy and decreased white matter integrity with performance decrements on different cognitive tasks across the life-span. Here, we correlated functional homotopy, both at the whole-brain level and specifically in fronto-parietal network nodes, with task-switching performance in young adults. Cue-to-target intervals (CTI: 300 vs. 1200 ms) were manipulated on a trial-by-trial basis to modulate cognitive demands and strategic control. We found that mixing costs, a measure of task-set maintenance and moni…

TRANS-CRANIAL MRI-GUIDED FOCUSED ULTRASOUND SURGERY (TCMRGFUS): ITALIAN AND WORLD-FIRST EXPERIENCE AT 1.5 TESLA

2016

Introduction: Transcranial magnetic resonance-guided focused ultrasound surgery (tcMRgFUS) is a promising new technology for the noninvasive treatment of various brain disorders. Here, we present our preliminary results achieved with the first Italian installation of a transcranial MRI-guided focused ultrasound surgery (tcMRgFUS) certified system for functional neurosurgery. Technical issues faced to achieve a safe and effective treatment will be discussed focusing on MR high-resolution live imaging and thermometry sequences optimization. Materials and Methods: Patient enrollment was based on indication for functional neurosurgery and evidence of medication-refractory disease; a detailed me…

GEL DOSIMETERS FOR RADIOTHERAPY APPLICATIONS: RESULTS OF A “RESEARCH PROJECT OF NATIONAL INTEREST” (PRIN)

2016

Introduction: Gel dosimeters for three-dimensional mapping of radiotherapy doses were introduced at Yale University in the mid-1980’s. Soon after, research and development in this field also started in Italy. Early work was done at the Istituto Superiore di Sanità and at the Universities of Pisa and Milan. Several institutes now collaborate on this topic with the goal of developing new formulations of hydrogel matrices with improved characteristics of stability, sensitivity and spatial resolution compared to those of earlier Fricke-gel and polymer-gel systems. Materials and methods: Contrary to earlier gels based on natural gelling agents, such as porcine skin gelatin and/or agarose, which …

Multiparametric MRI-based Dosimetric Parameters Best Predict Short-term Time Course of PSA After Iodine 125 Permanent Prostate Implantation for Local…

2012

International audience; D90% and V150% of the entire prostate are recognized as the best dosimetric predictors of outcome after 125 I permanent prostate implantation (PPI). The purpose of this study was 2-fold: 1) to determine the relationship between dose-volume parameters of the Dominant Intraprostatic Lesion (DIL) when compared to the prostate and early biochemical outcome after PPI; 2) to define if dose-volume parameters of the central gland (CG), the peripheral zone (PZ) and the DIL could best predict PSA bounce occurrence. The time course of PSA and mechanisms of bounces still remain unclear after PPI. Patients who had a higher dose in the DIL had a worse PSA level at 1 year which is …

The Neural Bases of Event Monitoring across Domains: a Simultaneous ERP-fMRI Study.

2017

The ability to check and evaluate the environment over time with the aim to detect the occurrence of target stimuli is supported by sustained/tonic as well as transient/phasic control processes, which overall might be referred to as event monitoring. The neural underpinning of sustained attentional control processes involves a fronto-parietal network. However, it has not been well-defined yet whether this cortical circuit acts irrespective of the specific material to be monitored and whether this mediates sustained as well as transient monitoring processes. In the current study, the functional activity of brain during an event monitoring task was investigated and compared between two cognit…

USE-Net: Incorporating Squeeze-and-Excitation blocks into U-Net for prostate zonal segmentation of multi-institutional MRI datasets

2019

Prostate cancer is the most common malignant tumors in men but prostate Magnetic Resonance Imaging (MRI) analysis remains challenging. Besides whole prostate gland segmentation, the capability to differentiate between the blurry boundary of the Central Gland (CG) and Peripheral Zone (PZ) can lead to differential diagnosis, since tumor's frequency and severity differ in these regions. To tackle the prostate zonal segmentation task, we propose a novel Convolutional Neural Network (CNN), called USE-Net, which incorporates Squeeze-and-Excitation (SE) blocks into U-Net. Especially, the SE blocks are added after every Encoder (Enc USE-Net) or Encoder-Decoder block (Enc-Dec USE-Net). This study ev…

Diffusion map for clustering fMRI spatial maps extracted by Indipendent Component Analysis

2013

Functional magnetic resonance imaging (fMRI) produces data about activity inside the brain, from which spatial maps can be extracted by independent component analysis (ICA). In datasets, there are n spatial maps that contain p voxels. The number of voxels is very high compared to the number of analyzed spatial maps. Clustering of the spatial maps is usually based on correlation matrices. This usually works well, although such a similarity matrix inherently can explain only a certain amount of the total variance contained in the high-dimensional data where n is relatively small but p is large. For high-dimensional space, it is reasonable to perform dimensionality reduction before clustering.…

Transient dynamics of pulse-driven memristors in the presence of a stable fixed point

2019

Abstract Some memristors are quite interesting from the point of view of dynamical systems. When driven by narrow pulses of alternating polarities, their dynamics has a stable fixed point, which may be useful for future applications. We study the transient dynamics of two types of memristors characterized by a stable fixed point using a time-averaged evolution equation. Time-averaged trajectories of the Biolek window function memristor and resistor-threshold type memristor circuit (an effective memristor) are determined analytically, and the times of relaxation to the stable fixed point are found. Our analytical results are in perfect agreement with the results of numerical simulations.