MR imaging and spectroscopy in PKU

Phenylketonuria (PKU) is an autosomal recessive disorder that results in th e accumulation of phenylalanine in the blood and soft tissues. Elevated lev els of phenylalanine have neurotoxic effects on the developing brain, resul ting in mental retardation. Early diagnosis and treatment limits the neurol ogical damage. Magnetic resonance imaging (MRI) changes are seen in the whi te matter on T-2 weighted imaging in many subjects. The severity of the cha nges do not correlate with clinical measures of neurological health. The ch anges correlate best with recent phenylalanine control. The levels of brain phenylalanine concentration using magnetic resonance spectroscopy (MRS) ha ve been shown not to correlate tightly with the blood phenylalanine concent ration. The individual variation in the brain to blood phenylalanine is lar ge. This individual variability may be responsible for different clinical o utcomes in PKU subjects who have similar long-term blood concentrations of phenylalanine. MRDD Research Reviews 1999;5:132-135. (C) 1999 Wiley-Liss, I nc.