MRI abnormalities in neurofibromatosis type 1 (NF1): a study of men and mice.

Hyperintense lesions on T2-weighted MR images of the brain, predominantly located in the basal ganglia, the brainstem and cerebellum, are a frequent finding in patients with neurofibromatosis type 1. Nature and significance of these lesions are still unknown so that the term 'unidentified bright objects' (UBOs) has been introduced to allow an unbiased description. We analyzed brain MRI scans of 31 children with definite diagnosis of neurofibromatosis type 1 according to the NIH criteria. High-intensity lesions on T2-weighted images were present in 86% of the patients. They did not correlate to other MRI findings such as optic pathway gliomas and were not indicative of intellectual impairment. Additionally, brain MR imaging of Nf1 knockout mice was performed to find out if similar abnormalities are present in this animal model. A total of 9 Nf1 knockout mice was examined on a dedicated animal MRI scanner at 4.7 Tesla but no evidence of high-signal intensity lesions on T2-weighted images was found. Therefore, the Nf1 mouse model seems to be unhelpful in providing further insights into the histological basis of hyperintense MRI abnormalities in NF1 patients.