Functional cardiac MRI in preterm and term newborns

Abstract

ObjectiveTo use cardiac MRI techniques to assess ventricular function and systemic perfusion in preterm and term newborns, to compare techniques to echocardiographic methods, and to obtain initial reference data.DesignObservational magnetic resonance and echocardiographic imaging study.SettingNeonatal Unit, Queen Charlotte's and Chelsea Hospital, London, UK.Patients108 newborn infants with median birth weight 1627 (580–4140) g, gestation 32 (25–42) weeks.ResultsMean (SD) flow volumes assessed by phase contrast (PC) imaging in 28 stable infants were left ventricular output (LVO) 222 (46), right ventricular output (RVO) 219 (47), superior vena cava (SVC) 95 (27) and descending aorta (DAo) 126 (32) ml/kg/min, with flow being higher at lower gestational age. Limits of agreement for repeated PC assessment of flow were LVO ±50.2, RVO ±55.5, SVC ±20.9 and DAo ±26.2 ml/kg/min. Mean (SD) LVO in 75 stable infants from three-dimensional models were 245 (47) ml/kg/min, with limits of agreement ±58.3 ml/kg/min. Limits of agreement for repeated echocardiographic assessment of LVO were ±108.9 ml/kg/min.ConclusionsDetailed magnetic resonance assessments of cardiac function and systemic perfusion are feasible in newborn infants, and provide more complete data with greater reproducibility than existing echocardiographic methods. Functional cardiac MRI could prove to be a useful research technique to study small numbers of newborn infants in specialist centres; providing insights into the pathophysiology of circulatory failure; acting as an outcome measure in clinical trials of inotropic intervention and so guiding clinical practice in the wider neonatal community.

Non-Invasive Cardiac Output Monitoring in Preterm Infants Undergoing Patent Ductus Arteriosus Ligation: A Comparison with Echocardiography

“…An inappropriately low C value for very small preterm infants would result in a systematic underestimation of SV by NICOM. While echocardiography is not a gold standard, it is the current standard of care and has been reported to have excellent inter-observer reliability [16] and agreement with cardiac magnetic resonance imaging estimates of LVO in populations of preterm and term infants [17,18,19]. Echocardiography also demonstrated good reliability and consistency with repeated measures compared with invasive measures of CO in a pediatric population [20].…”

Disruption of intracardiac flow patterns in the newborn infant

“…However, rotational patterns were consistently seen in adult subjects using the same free-breathing technique, and neonatal CMRI image quality appears to be less vulnerable to respiratory-motion artifact than adult imaging (19). Presence or absence of rotational flow was not associated with image-acquisition quality, flow could be reliably traced through to the phase of ventricular filling, and an unambiguous pattern of nonrotational flow was seen across a range of infant weights.…”

“…Atrial area was taken from a steady-state free-procession fourchamber image (19), with the atrial endocardial border traced from the last frame before tricuspid valve opening (37).…”

“…Prior studies examining circulatory physiology and pathophysiology of circulatory failure in the newborn have been hampered by the lack of sophistication in biomarkers of circulatory function (19). Arterial blood pressure, the most commonly measured marker of circulatory function, has a limited association with cardiac output (20).…”

“…Recently, CMRI techniques have been successfully applied to both the term and the preterm neonatal population (19,22), without sedation or anesthesia and while maintaining cardiorespiratory and thermal stability (23). CMRI has been shown to have significantly increased repeatability over echocardiography in the neonatal population and also provides greater intricacy than echocardiography as it allows assessment of filling of the cardiac chambers as well as ejection fraction (19).…”