Reliability of 3-D Virtual Abdominal Tele-ultrasonography in Pediatric Emergency: Comparison with Standard-of-Care Ultrasound Examination.

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. A prospective study was conducted between December 2020 and May 2021 that recruited 103 children undergoing ultrasound for abdominal pain. Trauma cases were excluded. Four tridimensional acquisitions were performed with a Smart Sensor 3D device (Canon Medical Systems, Otawara, Japan). Each tele-ultrasonography was secondarily blindly reviewed by two radiologists (one senior and one resident) with Fusion software (Canon Medical Systems). Acceptance and quality of the acquisitions were evaluated on a Likert scale. Inter-rater reliability was quantified using Cohen's κ coefficient and intraclass correlation coefficient. The ultrasound examination was normal in 66 cases (64%), abnormal in 36 cases (35%) and inconclusive in 1 case (1%). The acquisitions were obtained without objections from the children, their parents or the operators in more than 95% of cases. The quality of the acquisitions was considered good to excellent in 84% and 70% of cases. The sensitivity of the senior radiologist and the resident was 86% and 84%, respectively; specificity was 95% and 92%, positive predictive value 92% and 86% and negative predictive value 92 and 91% when comparing the conclusions of the standard and the tele-ultrasound examinations. Cohen's κ coefficients of the diagnosis obtained with the standard and the tele-ultrasound examinations were 0.82 and 0.71, respectively. The inter-rater Cohen's κ coefficient was 0.84. The intraclass correlation coefficient between the standard abdominal examination and the 3-D tele-ultrasound reformatted images for the following quantitative variables on pathological cases was 0.99 (confidence interval: 0.98-0.99). Virtual abdominal tele-ultrasonography is a promising method in pediatric emergencies.

Vibration-controlled transient elastography for noninvasive evaluation of liver steatosis.

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. METHODS: Twenty-two healthy volunteers and 20 patients with steatosis were included. For each subject, we used a modified FibroScan, whose data had been processed by our algorithm to separate the two viscoelastic components, stiffness µ, and viscosity η. The liver elasticity µFibroscan measured by the FibroScan was also recorded. Mann-Whitney tests and receiver operating characteristics (ROCs) curve analyses were performed to compare the parameters between the two groups, and Pearson's correlation coefficients were used to assess the correlations between the parameters. RESULTS: We found a good correlation between η and µFibroscan (r = 0.75), and poor correlations between µ and both η and µFibroscan (r = 0.33 and r = 0.03, respectively). We also showed that η and µFibroscan were higher in patients with steatosis compared to healthy volunteers, with area under the ROCs (AUROC) curve at 0.814 and 0.891, respectively. Conversely, µ was not different between the two groups (AUROC = 0.557). CONCLUSIONS: Our novel method successfully separated the two viscoelastic properties of the liver, of which the parameter η is a sensitive indicator for steatosis.

Liver shear wave elastography and attenuation imaging coefficient measures: prospective evaluation in healthy children.

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. The aim of our study was to provide normal SWE and ATI liver values in healthy children. METHODS: A prospective monocentric study was conducted recruiting 86 children (45 boys and 41 girls) from a single University Hospital between January 2019 and June 2020, having a clinically indicated ultrasound examination, without a known or documented history of liver disease. Examinations were performed using an Aplio i800 (Canon Medical Systems) ultrasound system with an i8CX1 transducer. SWE measurements were obtained using a color map showing an automated measurement area grid overlay. ATI coefficients were generated automatically for each region of interest in the right liver. RESULTS: Overall median age for the pediatric population was 106 months (1-180 months; SD 49 months). Children were normal weighted. Liver SWE was available for all children. The median liver SWE was 4.6 kPa [3.3-6.6]. ATI yielded valid measurements in 77 patients. The median ATI coefficient was 0.65 [0.5-0.81] dB/cm/MHz. No impact of age, sex, weight and Body Mass Index was observed. CONCLUSION: SWE and ATI liver values were provided in healthy children. The normative quantitative data might be useful to characterize liver parenchyma in children better.

Acousto-elasticity of transversely isotropic incompressible soft tissues: characterization of skeletal striated muscle.

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 theflexor digiti minimimuscle, 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. We then provide measurements of the apparent shear elastic modulus along, and transversely to, the fibre axis for six healthy human volunteers of different age and sex. The results display a great variety across the six subjects. We find that the slope of the apparent shear elastic modulus along the fibre direction changes inversely to the maximum voluntary contraction (MVC) produced by the volunteer. We propose an interpretation of our results by introducing the S (slow) or F (fast) nature of the fibres, which harden the muscle differently and accordingly, produce different MVCs. A natural follow-up on this study is to apply the method to patients with musculoskeletal disorders or neurodegenerative diseases.

Early changes in renal resistive index and mortality in diabetic and nondiabetic kidney transplant recipients: a cohort study.

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). METHODS: We conducted a retrospective study in 1685 RTR between 1985 and 2017. The long-term predictive value of changes in RI value from 1 month to 3 months was assessed in diabetic and non-diabetic RTR. RESULTS: Best survival was observed in RTR with RI < 0.70 both at 1 and 3 months, and the worst survival was found in RTR with RI ≥ 0.70 both at 1 and 3 months (HR = 3.77, [2.71-5.24], p < 0.001). The risk of DWFG was intermediate when RI was < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 2.15 [1.29-3.60], p = 0.003) and when RI was ≥0.70 at 1 month and < 0.70 at 3 months (HR = 1.90 [1.20-3.03], p = 0.006). In diabetic RTR, RI was significantly associated with an increased risk of death only in those with RI < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 4.69 [1.07-20.52], p = 0.040). RI considered as a continuous variable at 1 and 3 months was significantly associated with the risk of DWFG in nondiabetic but not in diabetic RTR. CONCLUSION: RI changes overtime and this impacts differently diabetic and nondiabetic RTR. RI short-term changes have a strong prognosis value and refines the risk of DWFG associated with RI.

High-Frequency Transient Elastography Prototype to Assess Skin (Dermis) Fibrosis: A Diagnostic Study in Patients with Venous Insufficiency and Controls.

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). MATERIALS AND METHODS: This clinical study enrolled 48 patients at various stages of CVD and 48 paired healthy volunteers. Subjects underwent a clinical examination with an evaluation of Rodnan's fibrosis skin score. We studied the dermis thickness measured using ultrasound (US) and elasticity measurements using cutometer and HF-TE studied according to 3 cutaneous zones positioned on the leg. The area under the receiver operating characteristic curve (AUC) was calculated to evaluate the diagnosis performance for a combined parameter (PRL) based on a logistic regression model using both elasticity and dermal thickness. RESULTS: Patients with CVD had significantly higher values of skin elasticity than healthy subjects, 134.5 kPa and 132.1 kPa vs. 91.3 kPa, respectively. The dermis thickness also increased with escalation in CVD stage for all studied zones. The PRL parameter had an AUC value of 0.79 for all zones and stages of CVD clustered. The discriminating power of PRL increased with escalation of the CVD stage; with an AUC value of up to 0.89 for evolved stages, and a sensitivity and specificity of 0.79 and 0.89, respectively. CONCLUSION: HF-TE, coupled with a US measurement of dermis thickness, made it possible to propose a new biomarker, which proved to be a good diagnostic tool for skin fibrosis.

Left amygdala volume and brain tissue pulsatility are associated with neuroticism: an MRI and ultrasound study.

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). Middle-aged females with depression (n = 25) and without depression (n = 25) underwent clinical examination, magnetic resonance imaging (MRI) and ultrasound assessment (TPI). Neuroticism was positively associated with left amygdala volume and mean BTP in individuals without depression, in both simple and multiple regressions that included potential confounding factors such as age and body mass index. No association was found in the depressed group. We confirmed the role of the left amygdala in the brain physiology of neuroticism in nondepressed individuals. Moreover, we identified a novel mechanism associated with high neuroticism, namely BTP, that may reflect greater CBF and account for the increased risk of cerebrovascular disease in individuals with high neuroticism. Because neuroticism is considered a risk factor for depression, our paper provides potential objective biomarkers for the identification of subjects at risk for depression.

Risk factors and outcomes of early acute kidney injury in infective endocarditis: A retrospective cohort study.

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. RESULTS: A total of 276 patients were included: 220 (79.7%) had definite IE and 56 (20.3%) had possible IE. E-AKI occurred in 150 patients (53%). IE due to Staphylococcus aureus (OR 3.41; 95% CI 1.83-6.39; p<0.01), history of diabetes (OR 2.34; 95% CI 1.25-4.37; p<0.01), peripheral arterial disease (OR 2.59; 95% CI 1.07-6.23; p<0.05), immunological manifestations (OR 3.11; 95% CI 1.31-7.39; p=0.01), and use of norepinephrine (OR 3.44; 95% CI 1.72-7.02; p<0.01) were associated with E-AKI. In subgroup analysis, infectious disease consultation was associated with a lower risk of AKI at day 7 (OR 0.41; 95% CI 0.16-0.88; p=0.04). E-AKI was associated with 1-year mortality (OR 1.65; 95% CI 1.03-2.64; p=0.04) and chronic kidney disease progression (OR 2.23; 95% CI 1.30-3.82; p<0.01). CONCLUSIONS: E-AKI is common in IE and often associated with non-modifiable variables. Multidisciplinary management should be mandatory, and awareness of AKI diagnosis and etiological explorations should be raised.

A systematic review of ultrasound imaging and therapy in mental disorders.

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. RESULTS: A total of 81 articles were included. Various US techniques and markers have been used in mental disorders, including Transcranial Doppler and Intima-Media Thickness. Most of the studies have focused on characterizing the pathophysiology of mental disorders, especially vascular physiology. Studies on therapeutic applications are still scarce. DISCUSSION: US imaging has proved to be useful in characterizing vascular impairment and structural and functional brain changes in mental disorders. Preliminary findings also suggest potential interests for therapeutic applications. Growing evidence suggests that US imaging could provide a non-invasive, portable and low-cost tool for pathophysiological characterization, prognostic assessment and therapeutic applications in mental disorders.

Role of distal cerebral vasculature in vessel constriction after aneurysm treatment with flow diverter stents.

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. MATERIALS AND METHODS: Radiological images and demographic data were acquired for 142 aneurysms treated with a FDS. Vascular resistance was estimated from patient-specific anatomic data. Correlation analysis was used to identify correspondence between anatomic data and clinical outcome. Computational Fluid Dynamics was performed on a typical patient-specific model to evaluate the influence of FDS on flow. Relevant hemodynamic variables along the bifurcating vessels were quantitatively analyzed and validated with in vitro data obtained using power Doppler ultrasound. RESULTS: Statistical analysis showed a correlation between clinical outcome and FDS resistance to flow considering overall jailed vessel vascular resistance (r=0.5, P<0.001). Computational predictions of blood flow showed that hemodynamics is minimally affected by FDS treatment in the ophthalmic artery. CONCLUSIONS: Jailed vessels are affected by narrowing when resistance to flow from the FDS constitutes a larger proportion of the overall vessel resistance to flow. This knowledge may contribute to better understanding of intracranial hemodynamics after a FDS procedure and reinforce indications for flow diversion in the treatment of intracranial aneurysms.

When classical music relaxes the brain: An experimental study using Ultrasound Brain Tissue Pulsatility Imaging.

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. METHODS: 25 healthy volunteers were exposed via earphones to four 5-minute musical excerpts (two exciting and two relaxing musical excerpts) presented in a randomized order and intersected by 5 silence periods. Measures of BTP, Heart Rate (HR) and Skin Conductance (SC) were collected during the entire task. RESULTS: The BTP significantly decreased with relaxing music compared to silence, and especially with the excerpt 'Entrance of the Shades' by Minkus. The HR and SC, but not Heart Rate Variability, were also decreased with relaxing music. We found no significant effect of exciting music. DISCUSSION: We report, for the first time, that classical relaxing music decreases the amplitude of the brain pulsatile movements related to cerebral blood flow and mechanical properties of the brain parenchyma, which provides further evidence of the involvement of BTP in emotional reactivity. In addition, we validate the use of TPI as a non-invasive, portable and low cost tool for studies in psychophysiology, with the potential to be implemented as a biomarker in musicotherapy trials notably.

The association between renal resistive index and premature mortality after kidney transplantation is modified by pre-transplant diabetes status: a cohort study.

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). Donor and recipient characteristics at time of transplantation and at 3 months were reviewed. The long-term predictive value of RI for DWFG and the age-RI and arterial pressure-RI relationships were assessed. RESULTS: A total of 284/1800 (15.7%) patients had diabetes mellitus before transplantation. RI was <0.75 in 1327/1800 patients (73.7%). High RI was associated with a higher risk of DWFG in non-diabetic patients [hazard ratio (HR) = 3.39, 95% confidence interval 2.50-4.61; P < 0.001], but not in patients with pre-transplant diabetes (HR = 1.25, 0.70-2.19; P = 0.39), even after multiple adjustments. There was no interaction between diabetes and age. In contrast, there was an interaction between RI and pulse pressure. CONCLUSION: Our study indicates that RI is not a predictor of DWFG in diabetic renal transplant recipients, in contrast to non-diabetic recipients. These findings could be due to a different age-RI or pulse pressure-RI relationship.

Perfusion Quantification of Liver Metastases of Colorectal Cancer Treated with Anti-angiogenic-Based Therapy: Assessment of Intra- and Inter-observer Reproducibility of Parameters in Three Regions of Interest Outlining Lesions.

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. Another ROI was drawn in healthy liver parenchyma for normalization. Intra- and inter-observer reproducibility of these parameters was evaluated using intra-class correlation coefficients (ICCs). For the three ROIs, both intra- and inter-observer reproducibility were excellent (ICCs ≥0.9) for 50.8% absolute parameters and were moderate to good (0.7 ≤ ICC < 0.9) for 26.7% of them. In healthy liver parenchyma and for normalized parameters, reproducibility was moderate to excellent for 59.4% of intensity parameters and was low (ICC <0.7) for almost all temporal parameters. This study indicates that DCEUS is a reproducible tool for evaluating perfusion parameters.

Impact on renal resistive index of diabetes in renal transplant donors and recipients: A retrospective analysis of 1827 kidney transplant recipients.

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. The authors conducted a retrospective study in 1827 renal transplant recipients who received a kidney between 1985 and 2017, and had Doppler measurements at 3 months after transplant. Donor and recipient characteristics at the time of transplant and at 3 months were reviewed. Both donor diabetes and recipient diabetes were associated with RI in univariate analysis, but only recipient diabetes remained significantly associated in stepwise multivariate analyses (effect estimate on RI: +0.03 ± 0.005, P < 0.001). These findings were confirmed when RI was expressed as a binary variable using a cutoff of 0.75 (OR = 2.50 [1.77, 3.54], P < 0.001). Other determinants of RI were recipient characteristics (age, sex, systolic and diastolic blood pressure, and duration of dialysis). Donor characteristics were not associated with RI. Our results suggest that high RI observed in diabetic recipients shortly after transplant is primarily due to the new vascular environment, rather than to characteristics of the transplanted kidney. Therefore, RI reflects systemic rather than intra-renal changes.

Ultrasound Measures of Brain Pulsatility Correlate with Subcortical Brain Volumes in Healthy Young Adults.

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). Twenty-five females aged 18-55 with no history of significant medical disorder underwent magnetic resonance imaging and ultrasound assessment. The volumes of six subcortical regions known to be particularly sensitive to change in cerebral blood flow were measured and compared with brain pulsatility as assessed with TCD-PI and TPI. TCD-PI and TPI measures positively correlated with all subcortical regions, with the caudate nucleus having the strongest association. Linear regressions found that TCD-PI and TPI measures of brain pulsatility explained 16% to 67% of the variance of the subcortical volumes. Our results suggest that a greater pulsatility as assessed with ultrasound in healthy young adults may constitute a protective factor for brain structure. Ultrasound measures of brain pulsatility may be appropriate to provide costless, non-invasive, portable and highly sensitive markers of cerebral blood flow pulsatility related to brain structure.

One-step surgical removal of cutaneous melanoma with surgical margins based on preoperative ultrasound measurement of the thickness of the melanoma.

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. Therefore, we routinely determined tumour sonographic thickness in order to perform surgery as a single step. OBJECTIVES: To determine the proportion of patients who receive one-step surgery with adequate margins based on sonographic measurement of melanoma thickness and identify the reasons for differences between these two measurements. MATERIALS AND METHODS: A retrospective series of patients with melanoma, in which thickness was measured by ultrasound (20 MHz) from April 2007 to December 2015 prior to surgery. RESULTS: Ninety-nine melanomas were treated, of which 78 were removed in a single step with surgical margins based on sonometric thickness measurements; 71 of these (91%, 95% CI: 82-96) did not require re-excision, five had excessive margins, and two had insufficient margins. The correlation between the histometric and sonometric measurements was good; r=0.88. Significant absolute difference between sonometric and histometric measurements was associated with thickness, ulceration, and size of tumours, based on bivariate analysis. Thickness remained the only significant factor based on multivariate analysis. CONCLUSION: Measuring the thickness of melanoma with high-resolution ultrasound imaging equipment makes it possible to remove the melanoma in a single step with adequate margins in at least 82% of the cases in routine care.

Brain tissue pulsatility mediates cognitive and electrophysiological changes in normal aging: Evidence from ultrasound tissue pulsatility imaging (TPI).

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. Brain functioning associated with attentional abilities was assessed by measuring the P3b ERP component elicited through an auditory oddball paradigm. To assess vascular health, we used an innovative measure of the pulsatility of deep brain tissue, due to variations in cerebral blood flow over the cardiac cycle. Results showed (1) a classical effect of age on fluid neurocognitive measures (inhibition, fluid intelligence, magnitude and latency of the P3b) but not on crystallized measures, (2) that brain pulsatility decreases with advancing age, (3) that brain pulsatility is positively correlated with fluid neurocognitive measures and (4) that brain pulsatility strongly mediated the age-related variance in cognitive performance and the magnitude of the P3b component. The mediating role of the brain pulsatility in age-related effect on neurocognitive measures supports the vascular hypothesis of cognitive aging.

Development of a Fluid Dynamic Model for Quantitative Contrast-Enhanced Ultrasound Imaging.

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. However, this quantification is mainly hampered by two reasons: first, the quantification intrinsically solely relies on temporal intensity variation, the explicit spatial transport of the contrast agent being left out. Second, the exact relationship between the acquired US-signal and the local microbubble concentration is hardly accessible. This paper introduces the use of a fluid dynamic model for the analysis of dynamic CEUS (DCEUS), in order to circumvent the two above-mentioned limitations. A new kinetic analysis is proposed in order to quantify the velocity amplitude of the bolus arrival. The efficiency of proposed methodology is evaluated both in-vitro, for the quantitative estimation of microbubble flow rates, and in-vivo, for the classification of placental insufficiency (control versus ligature) of pregnant rats from DCEUS. Besides, for the in-vivo experimental setup, we demonstrated that the proposed approach outperforms the performance of existing TIC-based methods.

Does Portopulmonary Hypertension Impede Liver Transplantation in Cirrhotic Patients? A French Multicentric Retrospective Study.

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. METHODS: Patients with portopulmonary hypertension who underwent LT between 2008 and 2016 in 8 French centers were retrospectively included. Pulmonary artery pressure was established by right heart catheterization before and after LT. Primary endpoint was the normalization of pulmonary artery pressure after LT. RESULTS: Twenty-three patients who received liver transplant between 2008 and 2016 were included. Two (8.7%) patients died in the immediate posttransplant period from right heart failure. With appropriate vasoactive medical treatment and LT, pulmonary arterial pressure was normalized in 14 patients (60.8%), demonstrating recovery from portopulmonary hypertension. In univariate analysis, the use of vasoactive combination therapy was the only prognostic factor for pulmonary arterial hypertension normalization after LT. CONCLUSIONS: Treatment of portopulmonary hypertension with a combination of vasoactive drugs allows LT with acceptable postoperative cardiovascular-related mortality and normalization of pulmonary hypertension in the majority of the patients.