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Localized 4.7 T proton magnetic resonance spectroscopy in neonatal encephalopathy: Implementation, safety and preliminary interpretation of results

De Vita, E; Bainbridge, A; Cady, EB; Kinchesh, P; Ordidge, RJ; Cheong, J; ... Robertson, NJ; + view all (2005) Localized 4.7 T proton magnetic resonance spectroscopy in neonatal encephalopathy: Implementation, safety and preliminary interpretation of results. Imaging Decisions MRI , 9 (4) 31 - 41. 10.1111/j.1617-0830.2005.00059.x.

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Abstract

Magnetic resonance (MR) techniques have revolutionized the assessment of brain development and injury in the newborn. MR studies at 3 T or above are becoming widespread; however, given the high cost and complexity of high-field MR systems, it is important to assess their benefits and limitations for clinical practice. MR spectroscopy (MRS) studies at high field carry potential benefits such as improved signal-to-noise ratio (SNR) and chemical shift dispersion compared with 1.5 T. However, safety is a very important consideration as radiofrequency (RF) tissue heating and acoustic noise also increase with field strength. Furthermore, increased chemical-shift dependence of the position of the volume of interest (VOI), shorter transverse and longer longitudinal relaxation times constitute additional challenges. We describe the first in-vivo, proton MRS studies of newborn human brain at 4.7 T. Nine infants with neonatal encephalopathy, all ventilated and with continuous physiological monitoring, were studied. We used L-FOCI localization, mostly with a VOI centred on the thalami. The absence of 4.7 T results from healthy infants made it impossible to interpret pathological metabolite peak-area ratios. However, concentration ratios and concentrations should be field-strength independent and interpretable using control values acquired at lower field. Of eight infants with concentration-ratio measurements, seven had low [N-acetylaspartate (NAA)]/[choline (Cho)] and three increased [lactate]/[NAA]. Of the two infants with 'concentration' measurements both had low [NAA] and one reduced [creatine]. We used an adult coil and consequent RF power restrictions had repercussions for the minimum magnetization recovery time (TR). A smaller, neonatal coil should improve SNR and, with less RF power, relax TR constraints thereby enabling fuller exploitation of the potential of high-field MRS.

Type:Article
Title:Localized 4.7 T proton magnetic resonance spectroscopy in neonatal encephalopathy: Implementation, safety and preliminary interpretation of results
DOI:10.1111/j.1617-0830.2005.00059.x
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology
UCL > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute for Women's Health > Neonatology
UCL > School of BEAMS > Faculty of Engineering Science > Medical Physics and Bioengineering

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