Search results for " MRI"

58. White matter abnormalities in attention-deficit/hyperactivity disorder: A diffusion tensor imaging study in adult patients

2009

A multicenter measurement of magnetization transfer ratio in normal white matter

1999

To assess the importance of intercenter variations when measuring magnetization transfer ratio (MTR) in the brain, six European centers measured MTR in normal white matter. MTR ranged from 9 to 51 percent units (25 sequences). The effective flip angle of the saturating pulse divided by the pulse repetition time (ENRsat degrees/msec) was a good predictor of MTR (MTR = 3.25 ENRsat).

Brain structural alterations in Fabry disease: ROI-based and voxel-based analyses of diffusion tensor imaging parameters

2007

Plantar fascia evaluation with a low-field MRI scanner in weight-bering position: our initial experience in patients with plantar fasciitis and in he…

2009

Purpose: To assess the usefulness of weight-bearing examination of the ankle performed with a low-field MRI scanner in the evaluation of plantar fascia in normal healthy volunteers and in patients with a clinical evidence of plantar fasciitis. Methods and Materials: We retrospectively evaluated ankle MR examinations in two groups of 40 patients each, performed between January and July 2008. Spin echo T1W, Gradient echo T2W, and Short Tau Inversion Recovery (STIR) images were acquired with a 0.2 T scanner (G-Scan, Esaote Biomedica, Genoa, Italy) in both weight-bearing position and normal conventional supine position. A dedicated extremities transmitter/receiver coil was used. The lesion site…

Right ventricular diastolic function in post-surgical Tetralogy of Fallot patients: A pilot study to make a comparison between echocardiography and c…

2021

Background: right ventricular (RV) systolic dysfunction is associated with poor outcomes in Tetralogy of Fallot (ToF) patients. Conversely, the influence of diastolic dysfunction in this setting is poorly known. In addition, evaluation of RV diastolic function by cardiac MRI is rarely performed.Materials and methods: twenty-four surgically treated ToF patients were enrolled in the study (54% males; median age at study: 28 (18–50) years; median age at surgery: 1.9 (0.4–8.2) years. They were studied by echocardiography to assess RV diastolic function in terms of traditional and TDI-derived parameters. At cardiac MRI, RV diastolic function was assessed by using phase-contrast analysis of flow …

Role of the Apparent Diffusion Coefficient (ADC) values analysis in Diffusion Weighted Imaging (DWI-MR) in the characterization of prostatic disease …

Purpose To evaluate if apparent diffusion coefficient analysis on magnetic resonance imaging can differentiate between normal and pathological prostate tissue, including prostate cancer and precancerous conditions (ASAP and PIN). Materials and Methods Prostate MRI with endorectal coil was performed in 93 patients (mean age 65.4). Regions of interest were placed over suspicious areas, detected on MRI, and over areas with normal appearance, and ADC values were recorded. Statistical differences between ADC values of suspicious and normal areas were evaluated. Histopathological diagnosis, obtained from targeted biopsy in 51 patients and from prostatectomy in 42 patients, were correlated to ADC …

Assessment of lung microstructure with magnetic resonance imaging of hyperpolarized Helium-3

2005

Magnetic resonance imaging of the apparent diffusion coefficient (ADC) of hyperpolarized Helium-3 is a new technique for probing pulmonary microstructure in vivo. The aim of this study was the assessment of potential sources of systematic errors of the ADC measurement. The influence of macroscopic motion was determined by measurements at two different delays after initiating the breath-hold, and before and after cardiac arrest. An intercentre comparison was performed in two age- and lung function-matched groups of lung-healthy volunteers at two research sites. Moreover, measurements of diffusion anisotropy were performed. We found no dependency of the ADC as a function of the delay after st…

Automatic Quality Assessment of Cardiac MR Images with Motion Artefacts using Multi-task Learning and K-Space Motion Artefact Augmentation

2022

The movement of patients and respiratory motion during MRI acquisition produce image artefacts that reduce the image quality and its diagnostic value. Quality assessment of the images is essential to minimize segmentation errors and avoid wrong clinical decisions in the downstream tasks. In this paper, we propose automatic multi-task learning (MTL) based classification model to detect cardiac MR images with different levels of motion artefact. We also develop an automatic segmentation model that leverages k-space based motion artefact augmentation (MAA) and a novel compound loss that utilizes Dice loss with a polynomial version of cross-entropy loss (PolyLoss) to robustly segment cardiac st…

Illumination correction on biomedical images

2014

RF-Inhomogeneity Correction (aka bias) artifact is an important re- search field in Magnetic Resonance Imaging (MRI). Bias corrupts MR images alter- ing their illumination even though they are acquired with the most recent scanners. Homomorphic Unsharp Masking (HUM) is a filtering technique aimed at correcting illumination inhomogeneity, but it produces a halo around the edges as a side effect. In this paper a novel correction scheme based on HUM is proposed to correct the artifact mentioned above without introducing the halo. A wide experimentation has been performed on MR images. The method has been tuned and evaluated using the simulated Brainweb image database. In this framework, the ap…

Differential associations of age with volume and microstructure of hippocampal subfields in healthy older adults

2015

Hippocampal atrophy in advanced healthy aging has frequently been reported. However, the vulnerability of different hippocampal subfields to age-related atrophy is still a source of debate. Moreover, the association of age with the microstructural integrity of subfields is largely unknown. In this study, we investigated the associations between age and volume as well as microstructural integrity of hippocampal subfields using a three-dimensional (3D) surface mapping approach. Forty-three healthy older adults spanning the age range from 60 to 85 years underwent T1-weighted and diffusion-tensor imaging. Analyses demonstrated an association of age with hippocampal volume predominantly in the m…