Exploration of the potential of high resolution and contrast 7 Tesla MR brain imaging in neonates

Abstract

ABSTRACTBACKGROUNDUltra-high field MR imaging offers marked gains in signal-to-noise ratio, spatial resolution, and contrast which translate to improved sensitivity for pathology and anatomy. These benefits are particularly relevant for the neonatal brain, as it is rapidly developing and sensitive to injury. However, experience of imaging neonates at 7T has been limited due to regulatory, safety, and practical considerations.PURPOSETo establish a program for safely acquiring high resolution and contrast brain images from neonates on a 7T system.STUDY TYPEProspective case series.POPULATIONImages were safely acquired from 35 neonates on 44 occasions (median age 39+6 postmenstrual weeks, range 33+4 to 52+6; median body weight 2.93kg, range 1.57to 5.3kg) over a median of 49 mins 30 sec.FIELD STRENGTH/SEQUENCE7T, acquired sequences included T2 weighted (TSE), Actual Flip angle Imaging, functional MRI (BOLD EPI), susceptibility weighted imaging, and MR spectroscopy (STEAM).ASSESSMENTPeripheral body temperature, physiological measures (heart rate, oxygen saturations). Review of acquired images by Neonatal Neuroradiologists for visual identification of anatomy and pathology, and by radiographer and researcher for assessment of image quality.STATISTICAL TESTSTwo tailed paired t-test, P<0.05 was considered statistically significant.RESULTSThere was no significant difference between temperature before and after scanning (p=0.76). Image quality assessment compared favourably to state-of-the-art 3T acquisitions. Anatomical imaging demonstrated excellent sensitivity to structures which are typically hard to visualise at lower field strengths including the hippocampus, cerebellum, and vasculature. The potential of 7T imaging is highlighted using contrast mechanisms which are enhanced at ultra-high field including susceptibility weighted imaging, functional MRI, and MR spectroscopy.DATA CONCLUSIONWe demonstrate safety and feasibility of imaging vulnerable neonates at ultra-high field. Our preliminary imaging suggests ultra-high field has untapped potential to provide important new insights into brain development and pathological processes during this critical phase of early life.