267 research outputs found

    Temporal Convolution Networks for Real-Time Abdominal Fetal Aorta Analysis with Ultrasound

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    The automatic analysis of ultrasound sequences can substantially improve the efficiency of clinical diagnosis. In this work we present our attempt to automate the challenging task of measuring the vascular diameter of the fetal abdominal aorta from ultrasound images. We propose a neural network architecture consisting of three blocks: a convolutional layer for the extraction of imaging features, a Convolution Gated Recurrent Unit (C-GRU) for enforcing the temporal coherence across video frames and exploiting the temporal redundancy of a signal, and a regularized loss function, called \textit{CyclicLoss}, to impose our prior knowledge about the periodicity of the observed signal. We present experimental evidence suggesting that the proposed architecture can reach an accuracy substantially superior to previously proposed methods, providing an average reduction of the mean squared error from 0.31mm20.31 mm^2 (state-of-art) to 0.09mm20.09 mm^2, and a relative error reduction from 8.1%8.1\% to 5.3%5.3\%. The mean execution speed of the proposed approach of 289 frames per second makes it suitable for real time clinical use.Comment: 10 pages, 2 figure

    Real-time diameter of the fetal aorta from ultrasound

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    The automatic analysis of ultrasound sequences can substantially improve the efficiency of clinical diagnosis. This article presents an attempt to automate the challenging task of measuring the vascular diameter of the fetal abdominal aorta from ultrasound images. We propose a neural network architecture consisting of three blocks: a convolutional neural network (CNN) for the extraction of imaging features, a convolution gated recurrent unit (C-GRU) for exploiting the temporal redundancy of the signal, and a regularized loss function, called CyclicLoss, to impose our prior knowledge about the periodicity of the observed signal. The solution is investigated with a cohort of 25 ultrasound sequences acquired during the third-trimester pregnancy check, and with 1000 synthetic sequences. In the extraction of features, it is shown that a shallow CNN outperforms two other deep CNNs with both the real and synthetic cohorts, suggesting that echocardiographic features are optimally captured by a reduced number of CNN layers. The proposed architecture, working with the shallow CNN, reaches an accuracy substantially superior to previously reported methods, providing an average reduction of the mean squared error from 0.31 (state-of-the-art) to 0.09 ackslashmathrmmm2ackslashmathrmmm^2mm2, and a relative error reduction from 8.1 to 5.3%. The mean execution speed of the proposed approach of 289 frames per second makes it suitable for real-time clinical use

    Real-time diameter of the fetal aorta from ultrasound

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    The automatic analysis of ultrasound sequences can substantially improve the efficiency of clinical diagnosis. This article presents an attempt to automate the challenging task of measuring the vascular diameter of the fetal abdominal aorta from ultrasound images. We propose a neural network architecture consisting of three blocks: a convolutional neural network (CNN) for the extraction of imaging features, a convolution gated recurrent unit (C-GRU) for exploiting the temporal redundancy of the signal, and a regularized loss function, called CyclicLoss, to impose our prior knowledge about the periodicity of the observed signal. The solution is investigated with a cohort of 25 ultrasound sequences acquired during the third-trimester pregnancy check, and with 1000 synthetic sequences. In the extraction of features, it is shown that a shallow CNN outperforms two other deep CNNs with both the real and synthetic cohorts, suggesting that echocardiographic features are optimally captured by a reduced number of CNN layers. The proposed architecture, working with the shallow CNN, reaches an accuracy substantially superior to previously reported methods, providing an average reduction of the mean squared error from 0.31 (state-of-the-art) to 0.09 mm2, and a relative error reduction from 8.1 to 5.3%. The mean execution speed of the proposed approach of 289 frames per second makes it suitable for real-time clinical use

    Intrauterine growth restriction is associated with persistent aortic wall thickening and glomerular proteinuria during infancy

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    Low birth weight, caused either by preterm birth or by intrauterine growth restriction, has recently been associated with increased rates of adult renal and cardiovascular disease. Since aortic intima–media thickening is a noninvasive marker of preclinical vascular disease, we compared abdominal aortic intima–media thickness among intrauterine growth restricted and equivalent gestational age fetuses in utero and at 18 months of age. The relationship between intrauterine growth restriction, fetal aortic thickening, and glomerular function during infancy was measured by enrolling 44 mothers with single-fetus pregnancies at 32 weeks gestation: 23 growth restricted and 21 of appropriate gestational age as controls. Abdominal aortic intima–media thickness was measured by ultrasound at enrollment and again at 18 months of age. Fetuses with intrauterine growth restriction had significantly higher abdominal aortic intima–media thickness compared with age controls when measured both in utero and at 18 months. At 18 months, the median urinary microalbumin and median albumin–creatinine ratio were significantly higher in those infants who experienced intrauterine growth restriction compared to the controls. Our results show that intrauterine growth restriction is associated with persistent aortic wall thickening and significantly higher microalbuminuria during infancy

    Temporal Convolution Networks for Real-Time Abdominal Fetal Aorta Analysis with Ultrasound

    Get PDF
    The automatic analysis of ultrasound sequences can substantially improve the efficiency of clinical diagnosis. In this work we present our attempt to automate the challenging task of measuring the vascular diameter of the fetal abdominal aorta from ultrasound images. We propose a neural network architecture consisting of three blocks: a convolutional layer for the extraction of imaging features, a Convolution Gated Recurrent Unit (C-GRU) for enforcing the temporal coherence across video frames and exploiting the temporal redundancy of a signal, and a regularized loss function, called CyclicLoss, to impose our prior knowledge about the periodicity of the observed signal. We present experimental evidence suggesting that the proposed architecture can reach an accuracy substantially superior to previously proposed methods, providing an average reduction of the mean squared error from 0.31mm2 (state-of-art) to 0.09mm2, and a relative error reduction from 8.1% to 5.3%. The mean execution speed of the proposed approach of 289 frames per second makes it suitable for real time clinical use. © Springer Nature Switzerland AG 2018

    The Vascular Link Between Intrauterine Hypoxia and Postnatal Cardiovascular Pathology

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    The effect of intrauterine hypoxia on arterial development was evaluated with use of large and small animal models. Analyses included expression and deposition of extracellular matrix (ECM) proteins, differentiation and proliferation of vascular smooth muscle cells (VSMCs), intima formation and wall thickening. A comprehensive investigation of possible molecular, mechanical and hormonal mediators of altered arterial development was afforded by a sheep model with both acute and chronic hypoxemia studies, whereas a guinea pig model allowed for long-term study. Our findings show that chronically hypoxic fetal sheep and intrauterine growth restricted (IUGR) guinea pigs exhibit a reduction in elastic fibre content of the aorta. In adulthood, the deficiency in aortic elastic fibre content in growth restricted guinea pig offspring was amplified compared to the subtle changes observed in late fetal life. In severely hypoxic fetal sheep, more marked reduction in elastin content occurred with increases in wall thickness and VSMC content. Increased collagen paralleled elevated mRNA levels of procollagen I and transforming growth factor beta (TGF-β 1). Matrix metalloproteinase-2 (MMP-2) mRNA levels were inversely correlated with fetal arterial oxygen saturation and expression of its activator, membrane-type MMP (MTI-MMP), was elevated in severely hypoxic sheep. Marked neointima formation was also apparent in severely hypoxic fetuses concomitant with increased mRNA levels of E-selectin, indicating endothelial inflammation. These structural and molecular changes of the aorta in chronically hypoxic ovine fetuses occurred without changes in pressure or circulating cortisol levels. Further, while the hypoxic sheep showed no change in VSMC maturation, aortae of IUGR guinea pig fetuses and offspring had increased content of myosin heavy chain B (MHC-B), a marker iv of undifferentiated VSMCs. Aortae of growth impaired guinea pig offspring exhibited a left shift in the length-tension curve as measured ex vivo. Thus altered aortic development in association with chronic hypoxia or IUGR leads to persistent structural abnormalities and reduced compliance in later life. In contrast, acute hypoxic study in fetal sheep demonstrated increased elastin content of the carotid artery in association with intermittent hemodynamic changes and elevated cortisol and thus highlight that beneficial adaptations are possible under certain intrauterine insults

    Poor growth, social inequalities and coronary risk.

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    Data from 5 epidemiological studies, spanning an age range from childhood to late adult life, are used to investigate associations between components of height, used as markers of growth at different phases, and arterial stiffness, subclinical atherosclerosis and cardiovascular risk. The roles of prenatal growth and life course socioeconomic position are considered. In the 1946 Birth Cohort, shorter leg, but not trunk length, was associated with greater pulse pressure, a measure of arterial stiffness, in adult men and women. Longitudinal analyses suggested that these effects were due to a steeper rise of blood pressure with age, independent of potential confounders and mediators considered. In the Whitehall II Study, shorter leg and trunk length were both associated with adverse levels of several cardiovascular risk factors and also lower distensibility and greater stiffness of the carotid arteries in men. In a cross-sectional examination of Filipino-American women, coronary disease was most strongly associated with leg length, while diabetes prevalence was not associated with measures of growth, but highest in women who were socioeconomically disadvantaged in childhood and adulthood. Higher blood pressure levels were observed in children with shorter leg length, relative to total body height, of a contemporary US birth cohort at age 3 years. The contribution of prenatal growth was considered in all studies where birthweight was available and found to be limited. Finally, results from the first Whitehall Study suggested that associations between stature and cardiovascular mortality may differ by socioeconomic position. These findings lend some support to the hypothesis that factors limiting leg growth are associated with arterial stiffness, subclinical atherosclerosis and cardiovascular risk these associations may originate in childhood and be amplified with age. The specificity of leg length as a marker of early influences on growth that alter cardiovascular risk is questioned

    Very preterm birth and fetal growth restriction in adolescence - Cardiovascular and renal aspects

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    This thesis applied magnetic resonance imaging (MRI) to investigate to what extent very preterm birth due to early onset fetal growth restriction (FGR) impacts the cardiovascular system and kidneys in adolescence. The thesis further investigated whether FGR exacerbates the organ-specific effects of very preterm birth.Study I validated a widely available non-contrast enhanced MRI method for quantification of renal cortical and medullary parenchymal volumes and showed that kidney volumes can be quantified with high accuracy and precision.Study II validated an MRI method for pulse wave velocity (PWV) acquisition in neonates and adolescents and showed how the acquired PWV was influenced by commonly used MRI methods. The study proposed the use of 3D angiography images and the time-to-foot method for accurate and precise PWV acquisition.Study III implemented the proposed PWV method from Study II and 24-hour ambulatory blood pressure measurements and showed that very preterm birth due to early onset FGR was associated with higher, yet normal, blood pressure in adolescent boys while very preterm birth was associated with higher arterial stiffness in girls.Study IV showed that very preterm birth was associated with smaller ventricular volumes without alterations in left or right longitudinal and radial pumping. Early onset FGR did not exacerbate the effects of very preterm birth.Study V implemented the newly validated non-contrast enhanced MRI method from Study I together with biomarkers of kidney function. Very preterm birth due to FGR was associated with smaller total kidney and medullary kidneyvolumes, but not with markers of kidney dysfunction or renin-angiontensin-aldosterone system activation in adolescence.This thesis concludes that adolescents born very preterm with and without preceding fetal growth restriction show alterations in cardiovascular and renal morphology. Changes were more pronounced in girls. Cardiovascular andkidney function were however normal, possibly indicating a decreased long-term effect of very preterm birth and fetal growth restriction on these organ systems compared to earlier studies, where clear signs of increased risk were observed already in childhood and adolescence. As indicated by increases in blood pressure, male sex and fetal growth restriction might increase cardiovascular risk in those born preterm. Morphological changes in the heart and in the kidneys may still precede functional decline in this population, and the alterations observed could potentially be used as prognostic markers in the future

    Cardiovascular development of the preterm infant

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    The numbers of preterm births and cardiovascular deaths are increasing in most countries. The causes of both developments are multiple and apparently not related to each other. However, preterm birth might provide an increasing contribution to the burden of cardiovascular morbidity and mortality, since epidemiological evidence is growing that cardiovascular disease risk factors such as hypertension, ischemic heart disease and cerebrovascular events are linked to preterm birth. Despite this, most of the underlying mechanisms remain unknown. The overall concept of this thesis was to seek evidence for a perinatal origin of the changes seen in adults who were born preterm, regarding both vascular and cardiac function. For this purpose, we performed a longitudinal observational study, investigating diameter and intimamedia thickness of the aorta and carotid artery, and analyzing cardiac function during the first six months after preterm birth. In addition to well-established ultrasound methods, we applied innovative technology such as speckle-tracking echocardiography, since advances in myocardial imaging have facilitated the echocardiographic examination of preterm infants and even the detection of subclinical functional impairment. In preterm born infants, we found significant alterations of the development of the vascular and cardiac systems. The arteries we examined became significantly narrower and the intima-media thickened in relation to vessel diameter when they were compared to healthy infants born at term. In addition, we found significant differences in the left ventricular systolic and diastolic function, suggesting that myocardial remodeling may occur as an adaptive process of premature exposure towards the extra-uterine circulation. Early changes in the cardiovascular development of the preterm infant may persist and have long-term implications. In fact, adults born preterm exhibit similar alterations in cardiovascular structure and function to those found in our studies. As it is not currently possible to prevent preterm births or influence the developmental changes described in this thesis, we will meet more children and adolescents with remodeled vessels and hearts in the future. Further research on the underlying mechanisms is warranted. In addition, early and continued follow-up will be required if we are to determine the long-term and clinical significance, and to improve cardiovascular health in the growing population of individuals born preterm

    Cardiac left ventricular mass and arterial stiffness from childhood to early adulthood - association with cardiometabolic risk factors : the Special Turku Coronary Risk Factor Intervention Project (STRIP)

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    Background: Cardiac left ventricular mass and arterial stiffness are subclinical markers of cardiovascular disease which are associated with cardiovascular disease and clinical events in adulthood. Aims: The aim of this thesis was to study left ventricular mass and arterial stiffness in childhood and their determinants in terms of cardiometabolic risk factors and ideal cardiovascular health. This thesis also aimed to investigate the effect of a dietary and lifestyle intervention on ideal cardiovascular health and subclinical markers of cardiovascular disease. Subjects and methods: This thesis is a part of the prospective, randomized Special Turku Coronary Risk Factor Intervention Project (STRIP) that has followed initially over 1,000 children for 27 years. Their cardiometabolic risk factors have been repeatedly measured from childhood to adulthood. Children in the intervention group (n=540) have received dietary and lifestyle counseling aimed at improving the quality of dietary fat. Subclinical markers of atherosclerotic cardiovascular disease were examined using noninvasive ultrasonic measurements of carotid and aortic distensibility, pulse wave velocity, carotid intima-media thickness and cardiac left ventricular mass. This study analyses the data of the children who participated in the arterial ultrasound evaluations from the age of 11 to 19 years (n=420–503), and in the cardiac ultrasound assessments from the age of 15 to 19 years (n= 394–420). Results: Cardiac left ventricular mass and arterial stiffness increased with increasing age from childhood to early adulthood. In boys, the arterial stiffness increased more than in girls. It was found that current pulse pressure, weight and physical activity along with birth weight were associated with left ventricular mass in adolescence; overall these factors explained nearly 50% of the variation in left ventricular mass. Childhood blood pressure, body mass index, LDL cholesterol concentration and insulin resistance were associated with arterial stiffness. The dietary and lifestyle intervention was associated with ideal cardiovascular health in adolescence, however, it had no effect on left ventricular mass or arterial stiffness. Conclusions: Marked age-related arterial stiffening is evident already in childhood, particularly in boys. Several cardiometabolic risk factors determine arterial stiffness and cardiac structure already at an early age. Although the dietary and lifestyle intervention promoted ideal cardiovascular health in adolescence, the intervention did not change the subclinical markers of cardiovascular disease at this early age.Sydämen vasemman kammion massa ja valtimoiden jäykistyminen lapsuudesta varhaiseen aikuisuuteen – yhteys kardiometabolisiin riskitekijöihin. Sepelvaltimotaudin Riskitekijöiden Interventioprojekti (STRIP) Tausta: Sydämen vasemman kammion massa ja valtimoiden jäykistyminen ovat valtimoterveyden varhaismarkkereita, jotka ovat yhteydessä sydän- ja verisuonisairauksien päätetapahtumiin aikuisiällä. Tavoite: Väitöskirjatutkimuksen tavoitteena oli tutkia vasemman kammion massaa ja valtimoiden jäykistymistä lapsuudessa, sekä selvittää niitä määrittäviä tekijöitä kardiometabolisten riskitekijöiden ja ihanteellisen sydänterveyden mittareiden avulla. Lisäksi tutkimuksen tavoitteena oli selvittää ravitsemus- ja elämäntapaneuvonnan yhteyttä ihanteelliseen sydänterveyteen ja valtimoterveyden varhaisiin muutoksiin. Menetelmät: Väitöskirjatutkimus on osa prospektiivista, satunnaistettua Sepelvaltimotaudin Riskitekijöiden Interventioprojekti (STRIP) -tutkimusta, jossa on seurattu 27 vuoden ajan alun perin yli 1000 lasta. Tutkittavien lasten sydän- ja verisuonisairauksien riskitekijät on mitattu toistuvasti lapsuudesta aikuisuuteen. Ateroskleroottisen sydän- ja verisuonitaudin varhaisia muutoksia tutkittiin mittaamalla ultraäänellä kaulavaltimon ja aortan distensibiliteetti, pulssiaallon etenemisnopeus, kaulavaltimon intima-median paksuus sekä sydämen vasemman kammion massa. Interventioryhmän lapset (n=540) ovat saaneet ravitsemus- ja elämäntapaneuvontaa, jonka päätavoitteena on ollut ruokavalion rasvan laatuun vaikuttaminen. Tässä työssä käytettiin niiden lasten tietoja, jotka osallistuivat valtimoiden ultraäänitutkimukseen 11– 19 vuoden iässä (n=420–503) ja sydämen ultraäänitutkimukseen 15–19 vuoden iässä (n=394–420). Tulokset: Sydämen vasemman kammion massa kasvoi ja valtimot jäykistyivät lapsuudesta varhaiseen aikuisuuteen. Pojilla valtimoiden jäykistyminen oli voimakkaampaa kuin tytöillä. Tutkimuksessa havaittiin, että pulssipaine, paino ja liikunta sekä syntymäpaino olivat yhteydessä vasemman kammion massaan nuoruudessa selittäen lähes 50 % variaatiosta. Lapsuudessa mitattu verenpaine, painoindeksi sekä seerumin LDL-kolesterolipitoisuus ja insuliiniresistenssi olivat yhteydessä valtimoiden jäykistymiseen lapsuudesta varhaiseen aikuisuuteen. Ravitsemus- ja elämäntapaneuvonta oli yhteydessä ihanteelliseen sydänterveyteen nuoruudessa, mutta sillä ei havaittu olevan yhteyttä valtimoiden jäykistymiseen tai vasemman kammion massaan Johtopäätökset: Valtimot jäykistyvät iän myötä jo lapsuudessa - erityisesti pojilla. Useat kardiometaboliset riskitekijät ovat yhteydessä valtimoiden jäykistymiseen ja sydämen rakenteeseen jo varhaisella iällä. Ravitsemus- ja elämäntapaneuvonnalla voidaan edistää ihanteellista sydänterveyttä nuoruudessa, vaikkakaan se ei ollut yhteydessä valtimotaudin varhaismarkkereihin näin varhaisella iällä
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