Abstract:
To determine whether differences exist between neurofibromatosis type 1 (NF1) patients with or without focal lesions and healthy normal
volunteers in the metabolite ratios of normal appearing white matter, 27 patients with NF1 (with parenchymal lesion, MR positive, n: 17;
without parenchymal lesions, MR negative, n: 10) and 20 healthy volunteers underwent MRI and short TE (31 ms) proton MR spectroscopy
(MRS). In 17 patients with parenchymal lesions, 61 focal lesions were detected by MRI. MRS was performed from normal appearing frontal
and posterior parietal white matter (FWM and PWM) in NF1 and from control groups. NAA/Cr, Cho/Cr and MI/Cr ratios were calculated.
Significant increase in Cho/Cr and MI/Cr ratios were found in FWM and PWM in MR negative and positive groups when compared to
control group. NAA/Cr ratio in MR positive group was significantly decreased in FWM compared to control group. There were no
significant differences between FWM and PWM in all metabolite ratios of MR negative group. MI/Cr ratio in MR positive group was
significantly elevated in PWM compared to FWM. Metabolite changes detected by MRS could indicate demyelination and gliosis in normal
appearing white matter in all NF1 patients, and additionally neuroaxonal damage in the FWM of NF1 patients with focal lesions. For that
reason, in the clinical evaluation and follow-up of these patients MRS features of normal appearing white matter should be considered in
addition to focal lesions.
