MRI abnormalities in normal-appearing brain tissue of treated adult PKU patients.
OBJECTIVE
To detect possible subclinical pathological brain changes a study on adult phenylketonuria (PKU) patients by using quantitative MRI methods was performed, since neuropsychological and cognitive deficits in treated patients with PKU have not yet been shown to correlate clearly with the brain lesions identified by conventional MRI.


METHODS
Eight subjects, four PKU patients with well-documented dietary treatment and four age- and sex-matched adult controls, underwent MRI, including a triple echo sequence and a diffusion tensor imaging sequence. Brain maps of T2 relaxation time (T2), relative proton density (PD), and fractional anisotropy (FA) as well as apparent diffusion coefficient (ADC) were derived for each subject. T2, PD, FA, and ADC were measured in 22 predefined regions of gray matter (GM) and white matter (WM) on the corresponding maps, and compared with those of four age-matched healthy adult controls.


RESULTS
In addition to a prolonged T2 value measured in affected WM, as expected, we observed a significant shortening of the T2 relaxation time and reduction of ADC in normal-appearing brain tissue and an increased proton density in both GM and WM of the patients. No differences were observed in FA values between controls and patients.


CONCLUSIONS
Repeatedly reduced T2 relaxation time, ADC, and increased proton density without changes in FA indicate a higher cell-packing density in normal-appearing brain without changes in the directedness of fibers. These structural changes may be related to neuropsychological and cognitive deficits in treated PKU patients.
Ding
Xiao-Qi
XQ
Department of Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. ding.xiaqi@mh-hannover.de
Fiehler
Jens
J
Kohlschütter
Brigitte
B
Wittkugel
Oliver
O
Grzyska
Ulrich
U
Zeumer
Hermann
H
Ullrich
Kurt
K
D000293:Adolescent; D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010661:Phenylketonurias / Q000178:diet therapy / Q000473:pathology*