T2 hyperintensities (T2H) on MRI are the most common CNS lesions in individuals with neurofibromatosis type 1 (NF1).
The aim was to determine the frequency, signal characteristics and localization of T2H at different ages. In addition, we examined the sensitivity of different MR imaging sequences in detecting these lesions.
We studied prospectively a cohort of children, adolescents and young adults with NF1 using T2-volume (T2-V) and conventional MRI sequences. Lesions were designated as either discrete or diffuse, and the region of signal abnormality was recorded. A total of 103 patients were studied (age range 8.0-25.4 years, mean 13.9 years).
The frequency, size, and intensity of T2H decreased with age in the basal ganglia (BG) and the cerebellum/brainstem (CB/BS). The majority of thalamic and CB/BS lesions were diffuse. Of the total cohort, 80% had diffuse bilateral hippocampal hyperintensities and 18.4% had hemispheric lesions best demonstrated on FLAIR; there was no significant difference in the frequency or signal intensity of hemispheric lesions with age.
Lesions in the cerebral hemispheres and hippocampus imaged by MR do not change in prevalence over time, suggesting a different pathological basis from the lesions in the in BG and CB/BS that resolve with age. FLAIR and T2-V sequences are more sensitive in detecting lesions than standard T2-weighted sequences.
"Despite their high frequency among NF1 patients, attempts to include this sign in the diagnostic criteria failed (Lopes et al. 2008). NBOs are located mainly in the basal ganglia, brain stem and cerebellum and often disappear in adulthood (Gill et al. 2006). NBOs in general were suspected to cause cognitive impairment such as hyperactivity, ADHD, lower intellect and spaciomotor functions impairment (Feldmann et al. 2003). "
[Show abstract][Hide abstract] ABSTRACT: Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders with mainly mild cutaneous mani-festations. Some patients with NF1, however, develop severe complications such as progressive optic pathway glioma, plexiform neurofibroma or malignant peripheral nerve sheath tumour. Due to potentially progressive and asymptomatic course of the disease, patients with NF1 require a regular multidisciplinary follow-up in coordination with various specialties and early inter-vention. In this article, we summarise our long-term experience with multidisciplinary follow-up of NF1 patients in the Centre for Neurofibromatosis Type 1 patients at the Children's University Hospital in Bratislava. Neurofibromatosis, genetic disorder, variable clinical manifestation, diagnostic criteria, genetic counselling, malignancy, follow-up, broad cooperation with specialists neurofibromatóza typu 1, variabilné klinické prejavy, diagnostické kritériá, genetické poradenstvo, tumor, klinické sledovanie, multidisciplinárny prístup Keywords Kľúčové slová Abstract Received February 20, accepted April 20, 2014
Acta Facultatis Pharmaceuticae Universitatis Comenianae 07/2014; 61(1). DOI:10.2478/afpuc-2014-0003
"Significant reductions in the number and intensity of T2H continued from 2000 to 2010, consistent with the hypothesis that these NF1 lesions tend to resolve over time [Gill et al., 2006]. The total number of lesions reduced by 35%. "
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND PURPOSE: Hyperintensities on T2-weighted images are seen in the brains of most patients with neurofibromatosis type I (NF-1), but the origin of these unidentified bright objects (UBOs) remains obscure. In the current study, we examined the diffusion characteristics of brain tissue in children with NF-1 to test the hypothesis that a microstructural abnormality is present in NF-1. MATERIALS AND METHODS: Diffusion tensor imaging (DTI) was performed in 50 children with NF-1 and 8 controls. Circular regions of interest were manually placed in 7 standardized locations in both hemispheres, including UBO sites. Apparent diffusion coefficients (ADC), fractional anisotropy (FA), and axial anisotropy (Am) were used to differentiate quantitatively between healthy and disordered brain matter. Differences in eigenvalues (1, 2, 3) were determined to examine parenchymal integrity. RESULTS: We found higher ADC values for UBOs than for normal-appearing sites (P.01) and higher ADC values for normal-appearing sites than for controls (P.04 in 5 of 7 regions). In most regions, we found no differences in FA or Am. Eigenvalues 2 and 3 were higher at UBO sites than in normal- appearing sites (P.04). CONCLUSION: With ADC, it was possible to differentiate quantitatively between normal- and abnormal- appearing brain matter in NF-1 and also between normal-appearing brain matter in NF-1 and healthy brain matter in controls, indicating subtle pathologic damage disrupting the tissue microstructure in the NF-1 brain. Higher diffusivity for 1, 2, and 3 could explain why this disturbance of microstructure is caused by accumulation of fluid or vacuolation.
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