Search results for "Diffusion"

Temperature Measurement by Diffusion-Weighted Imaging

2021

Diffusion-weighted imaging (DWI) thermometry is a magnetic resonance-based imaging tool that allows the noninvasive measurement of brain core temperature. Although only applicable to cerebrospinal fluid, it is thought to be potentially useful in assessing the thermal pathophysiology of the brain in both patients and healthy subjects. The objective of this article is to provide a concise but thorough review of the basic physical principles and the principal applications of DWI thermometry as a potential method to elucidate the pathophysiology of several brain diseases and neurologic syndromes.

Diagnostic potential of the diffusion tensor tractography with fractional anisotropy in the diagnosis and treatment of cervical spondylotic and postt…

2016

Background: Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI)-based methodology widely used for the evaluation of microstructural integrity of the central nervous system (CNS), particularly of brain white matter fibers and bundles. Methods: The most common parameters evaluated in a DTI study are the fractional anisotropy (FA) and mean diffusivity (MD). Combining FA and MD analyses is commonly used in the evaluation of various types of brain pathologies, such as brain tumors, where a combined analysis allows an accurate tumor characterization. Results: Recent studies have shown that FA and MD could be of value in non-oncologic spinal pathology. In this regard, it has been …

DEGENERATIVE CERVICAL MYELOPATHY: REVIEW OF SURGICAL OUTCOME PREDICTORS AND NEED FOR MULTIMODAL APPROACH

2020

Degenerative cervical myelopathy is the most common cause of spinal cord injury in the elderly population in the developed world, and it significantly affects the quality of life of patients and their caregivers. Surgery remains the only treatment option able to halt disease progression and provide neurological recovery for most patients. Although it has remained challenging to predict exactly who will experience improvement after surgery, increasingly it has been shown that clinical, imaging, and electrophysiological factors can predict, with relatively good capacity, those more likely to benefit. Clinically, the baseline neurological impairment appears to be strongly related to the outcom…

Non-alcoholic Wernicke's encephalopathy: From MRI findings of a case to differential diagnosis checklist

2018

Wernicke's encephalopathy is a serious neurological disorder secondary to thiamine deficiency in alcoholics. However, rarely it affects non-alcoholics. Here we present a case of Wernicke's encephalopathy in a non-alcoholic 56-year-old female, treated by endoscopic surgery for a duodenal ulcer two years before. She came to our attention for a sudden onset of a neurological syndrome characterized by visual deficits, diplopia, confusion, spatial disorientation and loss of short-term memory. An MRI scan showed the typical MRI findings of Wernicke's encephalopathy, which are discussed together with the possible differential diagnosis.

Diffusion-weighted MRI of cholesteatomas of the petrous bone

2002

Purpose To investigate if primary cholesteatomas of the petrous bone show high signal in diffusion-weighted imaging (DWI). Materials and methods In this blinded study, we compared 15 patients with clinically certain cases and later surgically proven cholesteatomas vs. 12 patients with clinically acute otitis of the middle ear and 20 volunteers without petrous bone disease. Two blinded readers without knowledge of the clinical data decided in consensus agreement whether there was a pathologic signal increase in the petrous bone in an anisotropic single-shot echo-planar imaging (EPI) DWI sequence, an artifact, or no signal increase. Results Thirteen of 15 patients with cholesteatomas showed b…

Mathematical Modelling of Local Regulation of Blood Flow by Veno-Arterial Diffusion of Vasoactive Metabolites

1997

It is widely accepted that vasoactive substances which are consumed or produced by tissue metabolism play a role in the adjustment of local perfusion rate to the metabolic needs of the tissue. In order to evoke a response of the vascular system, these substances — in the following for simplicity denoted by “vasodilators” even though oxygen, for example, is a vasoconstrictor — need to get into close contact with the small arterioles which represent the most powerful effectors in perfusion control. On the other hand, tissue sites in which supply with nutrients is most critical (“lethal corners”) and in which a vasodilator signal may be generated earliest, are located hundreds of µm away from …

IC‐P‐050: The European diffusion tensor imaging study in dementia (EDSD): Physical phantom study and multimodal clinical study on the diagnosis of Al…

2012

Multiparametric 18F-FDG PET-MRI of the breast: are there differences in imaging biomarkers of contralateral healthy tissue between patients with and …

2019

The rationale was to assess whether there are differences in multiparametric 18F-FDG PET/MRI biomarkers of contralateral healthy breast tissue in patients with benign and malignant breast tumors. Methods: In this institutional review board-approved prospective single-institution study, 141 women with imaging abnormalities on mammography or sonography (BI-RADS 4/5) underwent combined 18F-FDG PET/MRI of the breast at 3T with dynamic contrast-enhanced MRI, diffusion-weighted imaging, and the radiotracer 18F-FDG. In all patients, the following imaging biomarkers were recorded for the contralateral (tumor-free) breast: breast parenchymal uptake (BPU) (from 18F-FDG PET), mean apparent diffusion c…

Whole body magnetic resonance in indolent lymphomas under watchful waiting: The time is now.

2017

The indolent non-Hodgkin lymphomas (i-NHLs) are characterised by ‘indolent’ clinical behaviour with slow growth and prolonged natural history. The watchful waiting (WW) strategy is a frequently employed treatment option in these patients. This implies a strict monitoring by imaging examinations, including 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) and CT. A major concern is radiation exposure due to regularly monitoring by conventional imaging procedures. Several studies have demonstrated the reliability of whole-body magnetic resonance imaging (WB-MRI) for lymphoma staging. WB-MRI could be useful for active surveillance in i-NHLs providing the …

Quantitative myocardial perfusion magnetic resonance imaging: the impact of pulsatile flow on contrast agent bolus dispersion.

2011

Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels wit…