Reproducibility of cerebral phenylalanine levels in patients with phenylketonuria determined by 1H-MR spectroscopy

Kreis, R; Zwygart, K; Boesch, C; Nuoffer, J-M (2009). Reproducibility of cerebral phenylalanine levels in patients with phenylketonuria determined by 1H-MR spectroscopy. Magnetic resonance in medicine, 62(1), pp. 11-6. New York, N.Y.: Wiley-Liss 10.1002/mrm.21983

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The reproducibility of metabolite content determined by MR spectroscopy (MRS) is usually at best a few percent for the prominent singlets. When studying low-concentration metabolites, like phenylalanine (Phe), where tissue content can be <100 micromol/kg, better reproducibility is paramount-particularly in view of using MRS results for potential individual treatment advice. An optimized, targeted spectroscopy method was established at 1.5T and reproducibility was established in 21 patients with phenylketonuria (PKU) where three spectra were recorded in each of three independent sessions, two of which were in immediate succession to minimize physiologic variation. Intersession variation was found to be only 7 micromol/kg Phe for back-to-back repetition of sessions, in close agreement with the variation of 16 micromol/kg observed for single spectra within a session. Analysis of variance proved the individuality of the blood/brain Phe ratio-though this ratio seems to be influenced by physiologic factors that are not stable in time. The excellent reproducibility was achieved through optimization of various factors, including signal-to-noise ratio, repositioning, and prescan calibrations, but also by enforcing as much prior information as possible (e.g., lineshape and phase from reference scans, constant prior-knowledge-locked baseline). While the application of maximum general prior knowledge is a general method to reduce fluctuations, one should remember that it may introduce systematic errors.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM)
04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Institute of Clinical Chemistry

UniBE Contributor:

Kreis, Roland; Zwygart, Karin; Bösch, Christoph Hans and Nuoffer, Jean-Marc








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Date Deposited:

04 Oct 2013 15:13

Last Modified:

06 Dec 2013 13:59

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URI: (FactScience: 196954)

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