Publications by authors named "Patat Frederic"

Article Synopsis
  • Transcranial Doppler (TCD) ultrasound shows potential for quickly diagnosing large vessel occlusion (LVO) in patients with suspected acute ischemic stroke (AIS).
  • A systematic review analyzed 170 studies, narrowing down to 7 that included 2260 patients, with findings showing TCD-derived biomarkers have high accuracy (85.9% to 99.2%) for diagnosing LVO.
  • TCD appears effective and cost-efficient for improving stroke management, despite some limitations in data acquisition from certain patients.
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Ultrasound is currently recommended as the first-line examination for abdominal symptoms in children. However, a pediatric radiologist is not always available on site, especially during on-call duty. This study was aimed at evaluating the reliability of an innovative 3-D virtual abdominal tele-ultrasonography in this context.

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Background: Nonalcoholic fatty liver disease (NAFLD) refers to a large spectrum of liver disorders and is the most common cause of metabolic liver disease. The current gold standard for diagnosing NAFLD is liver biopsy, which can lead to severe complications.

Purpose: Among the noninvasive diagnostic options, we chose to use a FibroScan and developed an algorithm applying the Voigt rheological model to assess the viscoelastic properties of the liver and evaluate its performance for the diagnosis of steatosis.

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Using shear wave elastography, we measure the changes in the wave speed with the stress produced by a striated muscle during isometric voluntary contraction. To isolate the behaviour of an individual muscle from complementary or antagonistic actions of adjacent muscles, we select themuscle, whose sole function is to extend the little finger. To link the wave speed to the stiffness, we develop an acousto-elastic theory for shear waves in homogeneous, transversely isotropic, incompressible solids subject to an uniaxial stress.

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Purpose: Ultrasonographic quantitative measurements enable characterizing the stiffness and viscosity of liver parenchyma. Normal Shear Wave Elastography (SWE) values have been reported in adults and children. The Attenuation Imaging (ATI) coefficient is a measure of local sound energy loss thought to reflect steatosis in adults.

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Background: Renal resistive index (RI) predicts mortality in renal transplant recipients (RTR). However, its predictive value may be different according to the time of measurement. We analysed RI changes between 1 month and 3 months after transplantation and its predictive value for death with a functioning graft (DWFG).

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Objectives: The incidence of acute kidney injury (AKI) in infective endocarditis (IE), its risk factors and consequences on patient and renal survival remain debated.

Methods: Patients hospitalized for a first episode of IE (possible or definite according to modified Duke criteria) between 2013 and 2016 were included. The primary endpoint was to determine risk factors for early AKI (E-AKI) during the first week of management of IE.

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Brain changes associated with the personality trait of neuroticism have been partly elucidated. While subcortical brain volume changes, especially a larger amygdala, appear consistent in high neuroticism, functional changes, such as cerebral blood flow (CBF) differences, have shown conflicting results, possibly because of the limitations in methods of CBF measurement. In our study, we investigated changes in amygdala volume and CBF-related function associated with neuroticism in healthy and depressed subjects using both conventional magnetic resonance imaging (MRI) measures of brain volume and the innovative technique of ultrasound Tissue Pulsatility Imaging (TPI), which has a high level of detection in measuring brain tissue pulsatility (BTP).

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Purpose:  High-frequency transient elastography (HF-TE) is a noninvasive technique for assessing shear-wave speed and finally elasticity in thin tissue such as the skin. It has never been validated for monitoring fibrotic skin diseases. The purpose was to evaluate the potential of HF-TE to assess skin fibrosis in patients with chronic venous disorders (CVD).

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Background: Increasing evidence suggests that ultrasound (US) imaging may provide biomarkers and therapeutic options in mental disorders. We systematically reviewed the literature to provide a global overview of the possibilities of US for psychiatry.

Methods: Original English language articles published between January 2000 and September 2019 were identified through databases searching and analyzed to summarize existing evidence according to PRISMA methodology.

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Introduction: Recent evidence suggests that biomechanical parameters of the brain, such as Brain Tissue Pulsatility (BTP), could be involved in emotional reactivity. However, no study has investigated the impact of an emotional task on BTP. We used the ultrasound method of Tissue Pulsatility Imaging (TPI) to assess changes in BTP to exciting and relaxing classical music, in a musical perception task, as a validated paradigm to assess emotional reactivity.

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Background: Treatment of intracranial aneurysms with flow diverter stent (FDS) procedures can lead to caliber changes of jailed vessels. The reason some branches remain unchanged and others are affected by narrowing remains unknown.

Objective: To investigate the influence of resistance to flow from distal vasculature on stent-induced hemodynamic modifications affecting bifurcating vessels.

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This study evaluated the reproducibility of dynamic contrast-enhanced ultrasound (DCEUS) parameters outlining liver metastases of colorectal cancer in 45 patients, before and after anti-angiogenic-based therapy. Tumor enhancement was quantified by drawing three regions of interest (ROIs): (i) outlining the tumor based on portal phase DCEUS images, (ii) in the hypo-enhanced center of the lesion and (iii) outlining the lesion using parametric imaging. Perfusion parameters were extracted from time-intensity curves.

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Background: Renal resistive index (RI) predicts mortality in renal transplant recipients, but we do not know whether this is true in diabetic patients. The objective of this study was to analyse the long-term predictive value of RI for death with a functioning graft (DWFG) in renal transplant recipients with or without pre-transplant diabetes.

Methods: We conducted a retrospective study in 1800 renal transplant recipients between 1985 and 2017 who were followed for up to 30 years (total observation period: 14 202 patient years).

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High renal resistive index (RI) is observed in diabetes and is associated with poor patient survival, but whether it is primarily due to renal vascular resistance or systemic vascular alterations is unclear. The respective impact of kidney transplant from diabetic donors or to diabetic recipients on RI would shed some light on this issue. The objective of the study was to analyze the impact of donor and recipient diabetes on RI in order to understand the respective impact of the kidney and the vascular environment.

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Increasing evidence suggests that brain pulsatility is involved in the pathophysiology of various neurological and psychiatric disorders. However, it remains unclear whether high brain pulsatility is damaging to or protective of the brain in normal conditions, and this could depend on the age of the individual and the methods used to measure brain pulsatility. The goal of our study was to investigate associations between subcortical volumes and brain pulsatility as assessed with ultrasound in healthy young adults using both a conventional method (transcranial Doppler pulsatility index [TCD-PI]) and the innovative method of tissue pulsatility imaging (TPI), which allows a high level of detection of small brain movements (micrometers).

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Background: Surgical margins of melanoma vary from 5 mm to 1 or 2 cm depending on histology thickness (Breslow). This approach usually requires two surgical steps: excisional biopsy and further re-excision according to histology thickness. A previous systematic review showed that measuring melanoma thickness with high-resolution ultrasound imaging equipment correlates well with histological measurement of melanoma thickness.

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Aging is characterized by a cognitive decline of fluid abilities and is also associated with electrophysiological changes. The vascular hypothesis proposes that brain is sensitive to vascular dysfunction which may accelerate age-related brain modifications and thus explain age-related neurocognitive decline. To test this hypothesis, cognitive performance was measured in 39 healthy participants from 20 to 80 years, using tests assessing inhibition, fluid intelligence, attention and crystallized abilities.

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Background: Portopulmonary hypertension is defined by the presence of pulmonary arterial hypertension associated with portal hypertension. Its presence is a major stake for cirrhotic patients requiring liver transplantation (LT), with increased postoperative mortality and unpredictable evolution after transplantation. The aim was to study outcomes after liver transplantation in patients with portopulmonary hypertension and to identify factors associated with normalization of pulmonary hypertension.

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Background: Mechanisms involved in brain changes observed in major depression have been poorly investigated in clinical populations. Changes in cerebral blood flow (CBF) have been found in depressed patients and constitute a potential mechanism by which brain volume varies in depression. We have tested the association of cerebral blood flow velocity (CBFV) as assessed with Transcranial Doppler (TCD) and cerebral blood flow (CBF) as assessed with Arterial Spin Labeling Magnetic Resonance Imaging (ASL-MRI) with Total Brain Volume (TBV) and the volume of seven subcortical regions, in currently depressed and long-term remitted patients.

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Contrast-enhanced ultrasound (CEUS) is a non-invasive imaging technique extensively used for blood perfusion imaging of various organs. This modality is based on the acoustic detection of gas-filled microbubble contrast agents used as intravascular flow tracers. Recent efforts aim at quantifying parameters related to the enhancement in the vascular compartment using time-intensity curve (TIC), and at using these latter as indicators for several pathological conditions.

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Cerebrovascular disease (CVD) is consistently associated with late-life depression but poorly documented in midlife depression. It can be hypothesized that the relatively low sensitivity of conventional neuroimaging techniques does not allow the detection of subtle CVD in midlife depression. We used tissue pulsatility imaging (TPI), a novel ultrasound (US) neuroimaging technique that has demonstrated good sensitivity to detect changes in the pulsatility of small brain volumes, to identify early and subtle changes in brain vascular function in midlife depression.

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Neurofibromas (NFs) are benign tumours arising from a nerve sheath, which are present in nearly all patients with neurofibromatosis type 1 (NF1). High-frequency ultrasound (HFU) systems, using frequencies over 20 MHz, were developed to improve visualization of skin tumours by means of increased resolution. To describe NFs by using HFU in patients with NF1.

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Background: Orthostatic hypotension (OH) is highly prevalent in the elderly, and this population can be exposed to serious complications, including falls and cognitive disorders, as well as overall mortality. However, the pathophysiology of OH is still poorly understood, and innovative methods of cerebral blood flow (CBF) assessment have been required to accurately investigate cerebrovascular reactivity in OH.

Objectives: We want to compare brain tissue pulsatility (BTP) changes during an orthostatic challenge in elderly patients over 80 with and without OH.

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