Original article 1Institute of Clinical Sciences, Imperial College and MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK 2Division of Imaging Sciences, British Heart Foundation (BHF) National Centre, National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Guy’s and St Thomas’ National Health Service (NHS) Foundation Trust, King’s College London, London, UK 3Radiology Department and Center for Biomedical Imaging, Pontiﬁcia Universidad Catolica de Chile, Santiago, Chile Correspondence to Dr Alan Groves, Department of Paediatrics, Hammersmith House, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK; alan.groves@imperial.ac.uk Accepted 13 September 2010 Published Online First 21 October 2010 Functional cardiac MRI in preterm and term newborns Alan M Groves,1 Gaia Chiesa,1 Giuliana Durighel,1 Stephen T Goldring,1 Julie A Fitzpatrick,1 Sergio Uribe,2,3 Reza Razavi,2 Jo V Hajnal,1 A David Edwards1 ABSTRACT Objective To 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. Design Observational magnetic resonance and echocardiographic imaging study. Setting Neonatal Unit, Queen Charlotte’s and Chelsea Hospital, London, UK. Patients 108 newborn infants with median birth weight 1627 (580–4140) g, gestation 32 (25–42) weeks. Results Mean (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. Conclusions Detailed 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. More than 50 000 infants are born prematurely in the UK annually, with a socioeconomic burden of >£3 billion.1 Circulatory failure is responsible for a high proportion of neonatal mortality,2 particu- larly when associated with sepsis, and is impli- cated in the pathogenesis of neonatal cerebral3 and pulmonary injury.4 Cardiovascular physiology in the preterm infant is poorly understood and may differ signiﬁcantly from older children; as there is signiﬁcant dispar- ity in adrenergic receptor number, distribution and sensitivity.5 6 The effect of inotropic intervention in the preterm neonate is not well-described, lead- ing to a tenfold variation in inotropic intervention between neonatal units.7 Research to enhance understanding of neonatal circulatory failure is a priority.5 8 Functional echocardiographic techniques have been employed to study the neonatal circulation, however, currently available methods are unable to detect changes in volume of blood ﬂow of <30–40%,9–11 and cannot reliably assess ejection fraction (EF) due to asymmetric left ventricular contours.12 Cardiac magnetic resonance (CMR) has become the gold standard for functional assess- ment in adults,13 giving signiﬁcantly improved reproducibility over echocardiography,14 facilitat- ing reduced sample sizes for clinical trials of circu- latory intervention.15 We have installed a magnetic resonance scanner within our neonatal intensive care unit (NICU) to allow us to study extremely preterm infants while maintaining circulatory, respiratory and thermal stability.16 We have previously acquired basic cine CMR images in newborns without sedation or anaesthesia,17 but techniques had not previously been optimised or validated. The aim of this study was to utilise optimised CMR techniques to assess cardiac ﬁlling, cardiac output and systemic perfusion in a large cohort of preterm and term newborns, to test the hypothesis that neonatal CMR measures would provide greater detail and reproducibility than existing echocardiographic techniques, and to obtain initial reference data. SUBJECTS AND METHODS Subjects We studied infants who were inpatients at Queen Charlotte’s and Chelsea Hospital. MR imaging was approved by the Hammersmith Hospitals Trust Research Ethics Committee, and written parental consent was obtained for all studies. Infants were scanned solely for cardiac imaging research. All infants were stable at the time of imaging, whether receiving nasal continuous positive air- way pressure via an MR compatible system,16 low ﬂow supplemental oxygen or no respiratory sup- port. All infants were tolerating full enteral feeds. Cardiovascular magnetic resonance Scans were performed with a Philips 3-Tesla (Best, Netherlands) MR scanner. A paediatrician was present throughout. Infants were fed and allowed to fall into natural sleep without sedation or anaesthesia, then laid in an MRI-compatible cradle with ear protection, pulse oximetry and vector ECG monitoring.17 A Flex-M two-channel surface receiver coil was placed on either side of the chest wall. All sequences were acquired free- breathing, no respiratory compensation tech- niques were used. For all examinations, speciﬁc absorption rate (SAR) levels were within agreed safe limits (local SAR <10 W/kg, whole body SAR <0.8 W/kg). Entire imaging examination took 45–60 min. F86 Arch Dis Child Fetal Neonatal Ed 2011;96:F86–F91. doi:10.1136/adc.2010.189142