Clinical significance of brain phenylalanine concentration assessed by in vivo proton magnetic resonance spectroscopy in phenylketonuria

摘要: Recent studies using in vivo proton magnetic resonance spectroscopy (1H MRS) have suggested that plasma phenylalanine (Phe) may not be a reliable indicator of brain Phe level subjects with phenylketonuria (PKU). Interindividual variation cerebral can contribute to the phenotypic variability disease. We report results direct assessment by 1H MRS 10 off-diet PKU patients (aged 15.5–30.5 years), 4 detected and treated early, 6 late. In single patient, was evaluated before 15 days after diet discontinuation. FLAIR MRI were performed same setting 1.5 T clinical MR scanner. images scored according extent lobar white-matter hyperintensity. Brain signal (resonating at 7.36 ppm) as ratio creatine+phosphocreatine signal. correlated clinical, biochemical findings. Results follows. (1) An abnormal concentration all (ranging from 0.030 0.074), associated wide interindividual concurrent 724 2800 μmol/L). (2) late-detected subjects, phenotype better than did Phe. The discrepancy between relevant point view two cases: one, patient normal mental development, high relatively low Phe; other, subject severe neurological impairment, very compatible diagnosis mild PKU. (3) White-matter alterations patients. sequences disclosed an involvement optic chiasma tracts 7 subjects. No correlation found concentrations. (4) only case assessed under different intake Phe, increase paralleled showing useful tool evaluating individual vulnerability values