Search results for " MRI"
showing 10 items of 290 documents
Automatic classification of tissues on pelvic MRI based on relaxation times and support vector machine
2019
International audience; Tissue segmentation and classification in MRI is a challenging task due to a lack of signal intensity standardization. MRI signal is dependent on the acquisition protocol, the coil profile, the scanner type, etc. While we can compute quantitative physical tissue properties independent of the hardware and the sequence parameters, it is still difficult to leverage these physical properties to segment and classify pelvic tissues. The proposed method integrates quantitative MRI values (T1 and T2 relaxation times and pure synthetic weighted images) and machine learning (Support Vector Machine (SVM)) to segment and classify tissues in the pelvic region, i.e.: fat, muscle, …
Multicenter Multireader Evaluation of an Artificial Intelligence-Based Attention Mapping System for the Detection of Prostate Cancer With Multiparame…
2020
OBJECTIVE. The purpose of this study was to evaluate in a multicenter dataset the performance of an artificial intelligence (AI) detection system with attention mapping compared with multiparametric MRI (mpMRI) interpretation in the detection of prostate cancer. MATERIALS AND METHODS. MRI examinations from five institutions were included in this study and were evaluated by nine readers. In the first round, readers evaluated mpMRI studies using the Prostate Imaging Reporting and Data System version 2. After 4 weeks, images were again presented to readers along with the AI-based detection system output. Readers accepted or rejected lesions within four AI-generated attention map boxes. Additio…
Bilateral Wallerian degeneration of the medial cerebellar peduncles after ponto-mesencephalic infarction
2003
Three patients with acute large paramedian ponto-mesencephalic infarctions developed a bilateral retrograde degeneration of the medial cerebellar peduncles within 4 months after the insult. In an initial magnetic resonance imaging (MRI) within the first 2 weeks, the medial cerebellar peduncles showed normal intensities, but a control MRI after 4 months showed bright hyperintensities in the T2-TSE weighted images, and moderately increased signal intensities in echo planar imaging-diffusion weighted imaging were seen, possibly representing bilateral Wallerian degeneration of the cerebellar-pontine fibers.
ProstateAnalyzer: web-based medical application for the management of prostate cancer using multiparametric MR imaging
2016
Objectives: In this paper, we present ProstateAnalyzer, a new web-based medical tool for prostate cancer diagnosis. ProstateAnalyzer allows the visualization and analysis of magnetic resonance images (MRI) in a single framework. Methods: ProstateAnalyzer recovers the data from a PACS server and displays all the associated MRI images in the same framework, usually consisting of 3D T2-weighted imaging for anatomy, dynamic contrast-enhanced MRI for perfusion, diffusion-weighted imaging in the form of an apparent diffusion coefficient (ADC) map and MR Spectroscopy. ProstateAnalyzer allows annotating regions of interest in a sequence and propagates them to the others. Results: From a representat…
Effects of bilingualism on white matter atrophy in mild cognitive impairment: a diffusion tensor imaging study
2020
Background and purpose Previous investigations show that bilinguals exhibit the first symptoms of dementia 4-5 years later than monolinguals. Therefore, bilingualism has been proposed as a cognitive reserve mechanism. Recent studies have advanced towards an understanding of the brain mechanisms underlying bilingualism's protection against dementia, but none of them deals with white matter (WM) diffusion. Methods In this study, the topic was investigated by measuring WM integrity in a sample of 35 bilinguals and 53 passive bilinguals with mild cognitive impairment. Results No significant differences were found between the groups in cognitive level, education, age or sex. However, bilinguals …
Time course of lesion development in patients with acute brain stem infarction and correlation with NIHSS score.
2001
diffusion weighted magnetic resonance imaging (MRI) is highly sensitive in detecting acute supratentorial cerebral ischemia and Diffusion Weighted Imaging (DWI) lesion size has been shown to correlate strongly with the neurologic deficit in middle cerebral artery territory stroke. However, data concerning infratentorial strokes are rare. We examined the size and evolution of acute brain stem ischemic lesions and their relationship to neurological outcome.brain stem infarctions of 11 patients were analyzed. We performed DWI in all patients and in 7/11 patients within 24 h, T2W sequences within the first 2 weeks (10/11 patients) and follow-up MRI (MR2) within 3-9 months (median 4.8 months) la…
Functional implications of hippocampal volume and diffusivity in mild cognitive impairment.
2005
Abstract Hippocampal atrophy has been related to mild cognitive impairment (MCI) and early Alzheimer disease (AD), but the diagnostic significance of cross-sectionally determined hippocampal volumes is still ambiguous. Diffusion-Tensor-Imaging (DTI) in MCI patients revealed an association of microstructural changes in hippocampal areas with verbal memory decline. MRI volumetry and DTI were combined to investigate 18 MCI patients attending a memory clinic, and 18 carefully age- and gender-matched healthy controls. Neuropsychological testing, high resolution T1-weighted volume MRI scans, and DTI scans with regions-of-interest in hippocampal areas were applied. Left hippocampal volume was sign…
Vitamin D Intake and Magnetic Resonance Parameters for Knee Osteoarthritis: Data from the Osteoarthritis Initiative
2018
Purpose: There is evidence that vitamin D may play a role in the osteoarthritis (OA) pathogenesis, but the few data available are limited to X-rays and clinical findings. The aim of this study was to investigate whether a higher intake of vitamin D was associated with a better architecture of the cartilage of the knee, assessed with magnetic resonance (MRI), in a large cohort from North America. Methods: 783 participants (59.8% females; mean age: 62.3 years) with an MRI assessment from the Osteoarthritis Initiative were included. Vitamin D dietary intake was calculated as the sum of food and oral supplementation. A coronal 3D FLASH with Water Excitation MR sequence of the right knees was us…
Predicting conversion to dementia in mild cognitive impairment by volumetric and diffusivity measurements of the hippocampus.
2005
In our prospective study of diffusion tensor imaging (DTI), we measured hippocampal mean diffusivity (MD) and volumes in amnestic mild cognitive impairment (MCI). Thirteen MCI patients were followed-up by clinical assessment over a mean 112-year period. MCI patients who converted to dementia (6 of 13) during the observation period had slightly elevated left hippocampal mean diffusivity at baseline compared with MCI patients who remained clinically stable. Hippocampal volumes as well as baseline verbal memory and MMSE did not differ significantly between stable MCI patients and converters. Hippocampal diffusivity was superior to hippocampal volumes for prediction of conversion to dementia in…
Sequential contrast-enhanced magnetic resonance imaging in the diagnosis of growth hormone deficiencies
1999
The purpose of the present study was to assess the presence and the time-course of contrast-enhancement in the pituitary gland and pituitary stalk of 24 patients with isolated growth hormone (GH) deficiency and multiple pituitary hormone deficiency. The patients were evaluated clinically (auxological measurements), endocrinologically (spontaneous GH secretion and GH stimulation tests) and with conventional MRI scans. In addition, fast-framing dynamic magnetic resonance imaging (MRI) with Gd-DTPA enhancement was used to quantitate the time course of contrast enhancement within the neurohypophysis, pituitary stalk, postero-superior adenohypophysis and antero-inferior adenohypophysis. In 3 pat…