Neurofibromatosis type 1: diffusion weighted imaging findings of brain

The purposes of this study were to evaluate the differences in apparent diffusion coefficient (ADC) values between infra and supratentorial unidentified bright objects (UBOs), between UBOs and normal appearing side (NAS, contralateral regions of the UBOs and/or normal appearing region without UBOs) in the neurofibromatosis type 1 patients (NF1) and control group and also to investigate correlation between age and ADC values.

A total of 30 patients and 26 healthy controls were included. The MRI examination consisted of routine imaging and diffusion weighted imaging (DWI). Seven distinct locations (frontal, parieto-occipital and cerebellar white matter, globus pallidum, thalamus, hippocampus, and midbrain) were selected for the analysis. The ADC values were calculated directly from these automatically generated ADC maps with ROI.

The ADC values of UBOs were significantly increased in cerebellar white matter, hippocampus, globus pallidum, midbrain, and thalamus when compared with NAS and control group. There were statistically significant differences between NAS and control group in the ADC values obtained from hippocampus and thalamus. There were statistically significant differences between supra and infratentorial UBOs in ADC values. There was a negative correlation between age and the ADC values obtained from normal appearing midbrain, hippocampus, thalamus, and globus pallidum.

ADC values both in UBOs and in the normal appearing locations as hippocampus and thalamus were detected to be higher in the patients with NF1. The detection of lesions might be independent of MRI appearance in NF1, i.e. although the brain is affected, MRI appearance may be normal. Therefore, DWI and ADC values should also be utilized in the delineation of brain involvement of NF1 patients.