European Journal of Radiology Extra 54 (2005) 5–9 Diffusion-weighted imaging and proton MR spectroscopy of white matter abnormalities in a case of phenylketonuria Mehmet Teksam ∗ , Banu Cakir, Dilek Oguz, Ahmet Muhtesem Agildere Department of Radiology, Baskent University Medical School, Fevzi Cakmak Cd.10.Sok.No: 45, Bahcelievler, Ankara 06490, Turkey Received 25 May 2004; received in revised form 8 March 2005; accepted 10 March 2005 Abstract Phenylketonuria (PKU) is the most common congenital disorder of amino acid metabolism. We report diffusion-weighted imaging (DWI) and proton magnetic resonance (MRI) spectroscopy findings of white matter abnormalities in a 22-year-old woman with phenylketonuria. MRI demonstrated extensive abnormal signal changes in the periventricular white matter of cerebral hemispheres bilaterally. True restricted diffusion of water was identified in the corresponding abnormal white matter regions on DWI. Proton MR spectroscopy revealed mildly increased choline/creatine ratio, while the N-acetyl-l-aspartate/creatine ratio was normal. There was no phenylalanine peak at 3.80 and 7.36 ppm. The findings were most likely consistent with active inflammatory process causing progressive white matter degeneration. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Phenylketonuria; Diffusion-weighted imaging; Proton magnetic resonance spectroscopy 1. Introduction Phenylketonuria is an autosomal recessive genetic dis- ease in phenylalanine metabolism caused by a phenylalanine hydroxylase enzyme deficiency [1]. The most characteristic findings in untreated patients are neurological impairment such as mental retardation and abnormal motor development [2]. Dietary treatment starting in early infancy prevents these complications [3]. In this report, we present diffusion-weighted imaging (DWI) and proton MR spectroscopy (MRS) findings of phenylketonuria (PKU) in a 22-year-old woman. 2. Case report A 22-year-old woman with PKU who had been suffer- ing from headache was referred to our radiology department for MRI evaluation. She was diagnosed with PKU when she ∗ Corresponding author. Tel.: +90 312 212 6868x1163; fax: +90 312 223 7333. E-mail address: mehmett@baskent-ank.edu.tr (M. Teksam). was 25-day-old and she had been under dietary control since the time of diagnosis. Her intelligence appeared normal al- though IQ was not measured. Neurological examination in- cluding mental-motor activity and sensory pathways was un- remarkable. Her serum phenylalanine level was measured 15 mg/dl, 1 month prior to MR examination (normal range, 2–15 mg/dl). The MRI examination was performed on a 1.5 T MR unit (Siemens Magnetom Symphony, Erlangen, Germany) with an axial and sagittal T1-weighted spin echo, axial fluid-attenuated inversion recovery (FLAIR), coronal T2- weighted turbo spin echo, post-gadolinium axial and sagittal T1-weighted spin echo sequences. Conventional MR imag- ing demonstrated extensive periventricular white matter hy- perintensity in the periventicular white matter of both cere- bral hemispheres on T2 weighted images (Fig. 1A and B). Subcortical arcuate fibers were spared. In addition, diffusion-weighted images were obtained with diffusion gradient (b = 1000 mm 2 /s) and apparent diffusion coefficient values were calculated within bi- lateral frontal white matter (right: 0.656 × 10 -3 mm 2 /s; left: 0.657 × 10 -3 mm 2 /s), bilateral occipital white matter (right: 0.673 × 10 -3 mm 2 /s; left: 0.646 × 10 -3 mm 2 /s), 1571-4675/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2005.03.004