European Journal of Pediatrics

, Volume 159, Supplement 2, pp S121–S125

In vivo proton magnetic resonance spectroscopy in phenylketonuria

  • Harald E. Möller
  • Kurt Ullrich
  • Josef Weglage

DOI: 10.1007/PL00014374

Cite this article as:
Möller, H., Ullrich, K. & Weglage, J. Eur J Pediatr (2000) 159: S121. doi:10.1007/PL00014374


In vivo nuclear magnetic resonance spectroscopy permits the non-invasive examination of metabolic characteristics of the human brain in a clinical environment. Methods to detect elevated phenylalanine (Phe) in patients with phenylketonuria (PKU) using difference spectroscopy and to estimate absolute brain Phe concentrations, [Phe]brain, have been developed. In patients with classical PKU, [Phe]brain typically varied between 0.14 and 0.78 mmol/l depending upon actual blood Phe concentrations, [Phe]blood, between 0.47 and 2.30 mmol/l. Dynamic investigations can be used to extract information about Phe transport at the human blood-brain barrier, which may be described by a symmetric Michaelis-Menten model. Carrier saturation and competitive inhibition of the influx of other large neutral amino acids can be expected at blood levels usually found in PKU patients. In single cases of untreated, normal intelligent patients, abnormally low [Phe]brain ≤ 0.15 mmol/l were observed despite high stationary Phe levels ([Phe]blood=1.15 ± 0.10 mmol/l).

Conclusion Significant variations in phenylalanine transport parameters in untreated, normal intelligent patients indicated that blood-brain barrier transport or intracerebral phenylalanine consumption are causative factors for the individual vulnerability to phenylketonuria.

Key words Blood-brain barrierNuclear magnetic resonance spectroscopyPhenylalanine transportPhenylalanine turnoverPhenylketonuria
AbbreviationsBBB blood-brain barrierCr creatineNMR nuclear magnetic resonancePhe phenylalanine[Phe]blood blood Phe concentration[Phe]brain intracerebral Phe concentrationPKU phenylketonuriaPRESS point resolved spectroscopySTEAM stimulated echo acquisition modeT2 app apparent spin-spin relaxation timeTE echo timeVOI volume-of-interest

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Harald E. Möller
    • 1
  • Kurt Ullrich
    • 3
  • Josef Weglage
    • 4
  1. 1.Institute for Physical Chemistry, University of Münster, Schloßplatz 4/7, 48149 Münster, Germany e-mail: Tel.: +49-251-8356140; Fax: +49-251-8347312DE
  2. 2.Department of Clinical Radiology, University of Münster, Münster, GermanyDE
  3. 3.Department of Paediatrics, University Hospital Eppendorf, Hamburg, GermanyDE
  4. 4.Department of Paediatrics, University f Münster, Münster, GermanyDE