22 research outputs found

    Magnetic Resonance Imaging of the Neonatal Cardiovascular System : Impact of Patent Ductus Arteriosus

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    The incidence of premature birth is increasing in absolute number and as a proportion of all births around the world. Many pathologies seen in this cohort are related to abnormal blood supply. Fetal and premature cardiovascular systems differ greatly as to maintain adequate blood flow to the developing organs in the uterine and extra-uterine environments require very different circulations. Subsequently following preterm birth the immature cardiovascular system undergoes abrupt adaptations, often resulting in the prolonged patency of the fetal shunt, ductus arteriosus. The impact of a patent ductus arteriosus (PDA) is poorly understood. However it is thought that large ductal shunt volumes may result in congestive cardiac failure and systemic hypo-¬≠‚Äźperfusion. Cardiac MRI has contributed greatly to the understanding of many cardiovascular diseases and congenital defects in paediatric and adult patients. Translating these imaging techniques to assess the preterm cardiovascular system requires careful optimization due to their condition, size and significantly increased heart rate. The work presented in this thesis employs multiple functional CMR techniques to investigate the preterm cardiovascular system in the presence and absence of PDA and the resultant cardiac function. A novel technique utilizing PC MRI to quantify PDA shunt volume and its impact on flow distribution is presented. Despite large shunt volumes, systemic circulation remained within normal range, although slight reduction is detectable when assessed at group level. Subsequently the impact of PDA and associated increased work load on left ventricular dimensions and function was then investigated using SSFP imaging. Results indicated that cardiac function was maintained even in the presence of large shunt volumes. Finally 4D PC sequences were employed to evaluate pulse wave velocity and flow regime within the preterm aorta, demonstrating the feasibility of hemodynamic assessment in this cohort. The findings of these studies provide insight into the impact of PDA. The reliable measurement and assessment of preterm cardiovascular system provides the potential to improve the understanding of the development and effects of certain pathologies seen in this cohort.Open Acces

    Associations between Facial Emotion Recognition and Mental Health in Early Adolescence

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    Research shows that adolescents with mental illnesses have a bias for processing negative facial emotions, and this may play a role in impaired social functioning that often co-exists with a mental health diagnosis. This study examined associations between psychological and somatic problems and facial emotion recognition in early adolescence; as any processing biases in this age-group may be an early indicator of later mental illnesses. A community sample of 40 12-year-olds self-rated their symptoms of anxiety, depression, and somatization via two mental health screeners. They also completed a computerized emotion recognition task in which they identified photographs of 40 faces showing expressions of anger, fear, sadness, happiness, or neutral expression. Results showed that increased symptoms of anxiety, depression, and somatization were significantly associated with fewer correct responses to angry expressions. These symptoms were also associated with faster and more accurate recognition of fearful expressions. However, there was no association between mental health and recognition of sad affect. Finally, increased psychological and/or somatic symptomology was also associated with better identification of neutral expressions. In conclusion, youth with increased psychological and/or somatic problems exhibited a processing bias for negative anger and fear expressions, but not sadness. They showed better processing of neutral faces than youth with fewer psychological and/or somatic problems. Findings are discussed in relation to indicators of mental illnesses in early adolescence and the potential underpinning neural mechanisms associated with mental health and emotional facial recognition

    Cardiovascular magnetic resonance of cardiac function and myocardial mass in preterm infants:a preliminary study of the impact of patent ductus arteriosus

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    Background Many pathologies seen in the preterm population are associated with abnormal blood supply, yet robust evaluation of preterm cardiac function is scarce and consequently normative ranges in this population are limited. The aim of this study was to quantify and validate left ventricular dimension and function in preterm infants using cardiovascular magnetic resonance (CMR). An initial investigation of the impact of the common congenital defect patent ductus arteriosus (PDA) was then carried out. Methods Steady State Free Procession short axis stacks were acquired. Normative ranges of left ventricular end diastolic volume (EDV), stroke volume (SV), left ventricular output (LVO), ejection fraction (EF), left ventricular (LV) mass, wall thickness and fractional thickening were determined in ‚Äúhealthy‚ÄĚ (control) neonates. Left ventricular parameters were then investigated in PDA infants. Unpaired student t-tests compared the 2 groups. Multiple linear regression analysis assessed impact of shunt volume in PDA infants, p-value‚ÄȂȧ‚ÄČ0.05 being significant. Results 29 control infants median (range) corrected gestational age at scan 34+6(31+1-39+3) weeks were scanned. EDV, SV, LVO, LV mass normalized by weight and EF were shown to decrease with increasing corrected gestational age (cGA) in controls. In 16 PDA infants (cGA 30+3(27+3-36+1) weeks) left ventricular dimension and output were significantly increased, yet there was no significant difference in ejection fraction and fractional thickening between the two groups. A significant association between shunt volume and increased left ventricular mass correcting for postnatal age and corrected gestational age existed. Conclusion CMR assessment of left ventricular function has been validated in neonates, providing more robust normative ranges of left ventricular dimension and function in this population. Initial investigation of PDA infants would suggest that function is relatively maintained

    Impact of obesity and epicardial fat on early left atrial dysfunction assessed by cardiac MRI strain analysis

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    International audienceAbstractBackgroundDiastolic dysfunction is a major cause of morbidity in obese individuals. We aimed to assess the ability of magnetic resonance imaging (MRI) derived left atrial (LA) strain to detect early diastolic dysfunction in individuals with obesity and type 2 diabetes, and to explore the association between cardiac adipose tissue and LA function.MethodsTwenty patients with obesity and T2D (55¬†¬Ī¬†8¬†years) and nineteen healthy controls (48¬†¬Ī¬†13¬†years) were imaged using cine steady state free precession and 2-point Dixon cardiovascular magnetic resonance. LA function was quantified using a feature tracking technique with definition of phasic longitudinal strain and strain rates, as well as radial motion fraction and radial velocities.ResultsSystolic left ventricular size and function were similar between the obesity and type 2 diabetes and control groups by MRI. All patients except four had normal diastolic assessment by echocardiography. In contrast, measures of LA function using magnetic resonance feature tracking were uniformly altered in the obesity and type 2 diabetes group only. Although there was no significant difference in intra-myocardial fat fraction, Dixon 3D epicardial fat volume(EFV) was significantly elevated in the obesity and type 2 diabetes versus control group (135¬†¬Ī¬†31 vs. 90¬†¬Ī¬†30¬†mL/m2, p¬†<¬†0.001). There were significant correlations between LA functional indices and both BMI and EFV (p¬†‚ȧ¬†0.007).ConclusionsLA MRI-strain may be a sensitive tool for the detection of early diastolic dysfunction in individuals with obesity and type 2 diabetes and correlated with BMI and epicardial fat supporting a possible association between adiposity and LA strain.Trials Registration Australian New Zealand Clinical Trials Registry No. ACTRN1261300106974
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