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MR in phenylketonuria-related brain lesions.
Dezortova M, Hajek M, Tintera J, Hejcmanova L, Sykova E.
MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
PURPOSE: Phenylketonuria (PKU) patients were examined by different MR
techniques to explain the pathological changes observed in periventricular
white brain matter using conventional MR imaging. MATERIAL AND METHODS:
Fifteen patients with treated classical PKU were examined by 1H spectroscopy,
relaxometry and diffusion imaging on a whole-body 1.5-T MR imager. RESULTS:
Known PKU lesions characterized by T2 enhancement in periventricular white
matter were observed in all patients. The MR spectra from the lesioned
areas showed a significant decrease in choline concentration. The mean
ADC of water decreased and tortuosity increased in PKU lesions compared
to control data. CONCLUSION: The results support the following hypothesis:
The T2 increase in the PKU lesion reflects a raised concentration of free
water molecules (about 15%) that have an increased trajectory between collisions
compared to the same region in controls. The increase in water mobility
might be explained by changes in extracellular space volume and myelin
sheaths, which, presumably, have a different geometry with more hydrophobic
sites in PKU patients. The changes result in increased tortuosity and may
be confirmed by the loss of anisotropy in PKU lesions.
