Search results for "magnetic resonance angiography"
showing 10 items of 77 documents
Segmentation-Free Estimation of Aortic Diameters from MRI Using Deep Learning
2021
Accurate and reproducible measurements of the aortic diameters are crucial for the diagnosis of cardiovascular diseases and for therapeutic decision making. Currently, these measurements are manually performed by healthcare professionals, being time consuming, highly variable, and suffering from lack of reproducibility. In this work we propose a supervised deep-learning method for the direct estimation of aortic diameters. The approach is devised and tested over 100 magnetic resonance angiography scans without contrast agent. All data was expert-annotated at six aortic locations typically used in clinical practice. Our approach makes use of a 3D+2D convolutional neural network (CNN) that ta…
Abdominal and Thoracic Magnetic Resonance Angiography: Challenges, Technical Approaches, and First Clinical Applications
1993
The main goal of magnetic resonance angiography (MRA) is to enrich the huge potential of magnetic resonance imaging (MRI) by additional morphological and functional information about the vasculature. In spin echo sequences fast flowing blood leads to signal extinction, providing high contrast between tissue and vascular structures without the need for contrast media. However, various artifacts are frequently observed which alter the assessment of the vasculature. They are due to alterations of flow (slow velocity or turbulences) or induced by the acquisition technique (Mills et al. 1983; Bradley and Waluch 1985). By using gradient echo sequences, high-quality angiograms can be obtained from…
Sensitivity and specificity of MRA in the diagnosis of neurovascular compression in patients with trigeminal neuralgia
1998
The published rates of operatively confirmed neurovascular compression as the cause for trigeminal neuralgia range from 10 % to nearly 100 %. High-definition magnetic resonance angiography (MRA) was performed in 27 consecutive patients (in 6 cases with 3D reconstructions) to show neurovascular compression preoperatively. The MRA findings were compared with the relationship between the Vth nerve and the surrounding vessels at surgery. In 23 patients MRA showed present neurovascular compression in accordance with surgical findings (18/27 in complete accordance of type and side of vessel, site and direction of compression). One woman had no neurovascular compression either on MRA or intraopera…
Endovascular treatment for chronic cerebrospinal venous insufficiency: is the procedure safe?
2010
Objectives The aim of this report is to assess the safety of endovascular treatment for chronic cerebrospinal venous insufficiency (CCSVI). Although balloon angioplasty and stenting seem to be safe procedures, there are currently no data on the treatment of a large group of patients with this vascular pathology. Methods A total of 564 endovascular procedures (balloon angioplasty or, if this procedure failed, stenting) were performed during 344 interventions in 331 CCSVI patients with associated multiple sclerosis. Results Balloon angioplasty alone was performed in 192 cases (55.8%), whereas the stenting of at least one vein was required in the remaining 152 cases (44.2%). There were no majo…
A Novel Bio-Inspired Approach for High-Performance Management in Service-Oriented Networks
2021
Service-continuity in distributed computing can be enhanced by designing self-organized systems, with a non-fixed structure, able to modify their structure and organization, as well as adaptively react to internal and external environment changes. In this paper, an architecture exploiting a bio-inspired management approach, i.e., the functioning of cell metabolism, for specialized computing environments in Service-Oriented Networks (SONs) is proposed. Similar to the processes acting in metabolic networks, the nodes communicate to each other by means of stimulation or suppression chains giving rise to emergent behaviors to defend against foreign invaders, attacks, and malfunctioning. The mai…
Comparison of the quantitative first pass myocardial perfusion MRI with and without prospective slice tracking: Comparison between breath-hold and fr…
2010
Physiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion-MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs…
Imaging of cervical lymph node metastases in malignant jugular paraganglioma: Imaging of paraganglioma metastases
2009
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Non Invasive Imaging of Myocardial Infarction with Computed Tomography and Magnetic Resonance
2012
Myocardial infarction is a major cause of death and disability worldwide. Myocardial infarction may represent a major catastrophic event leading to severe hemodynamic failure or sudden death or it may occur repeatedly in patients with established heart disease. In this context, the role of imaging techniques may become useful for the understanding of the determinants in a preclinical setting before acute coronary events, and for an accurate and correct diagnosis of myocardial infarction. Three-dimensional noninvasive imaging techniques, such as Cardiac CT (CCT) and Cardiac MR imaging (CMR) were widely developed in the last two decades. These imaging techniques may provide new insights into …
Update on diagnostic strategies of pulmonary embolism
1999
Acute pulmonary embolism is a frequent disease with non-specific findings, high mortality, and multiple therapeutic options. A definitive diagnosis must be established by accurate, non-invasive, easily performed, cost-effective, and widely available imaging modalities. Conventional diagnostic strategies have relied on ventilation-perfusion scintigraphy complemented by venous imaging. If the results are inconclusive, pulmonary angiography, which is regarded as the gold standard, is to be performed. Recently, marked improvements in CT and MRI and shortcomings of scintigraphy led to an update of the diagnostic strategy. Spiral CT is successfully employed as a second-line procedure to clarify i…
Imaging of “Malignant” External Otitis
1997
“Malignant” external otitis or necrotizing external otitis (NEO) is a rare and severe infection of the external auditory meatus, causing destructive changes of the petrous bone, infiltrating inframastoid and intracranial tissues, with potentially lethal consequences. Five male diabetic patients, aged 61 to 85 years-old (mean age was 74 y.o), referred with biopsy-proven NEO, underwent CT and MRI studies for the assessment of the extension of the disease. Clinical data concerning the examined patients are summarized in table 1. Contrast-enhanced MRI does not seem to help in differentiating granulation from neoplastic tissues, as both demonstrate inhomogeneous enhancement. In conclusion, NEO …