ORIGINAL ARTICLE Unidentified bright objects on brain MRI in children as a diagnostic criterion for neurofibromatosis type 1 José Roberto Lopes Ferraz Filho & Marcos Pontes Munis & Antonio Soares Souza & Rafael Angelo Sanches & Eni Maria Goloni-Bertollo & Erika Cristina Pavarino-Bertelli Received: 7 September 2007 / Revised: 5 November 2007 / Accepted: 20 November 2007 / Published online: 30 January 2008 # Springer-Verlag 2007 Abstract Background Lesions of the brain denominated as uniden- tified bright objects (UBOs), which are not included in the diagnostic criteria for neurofibromatosis type 1 (NF1) established by the National Institutes of Health (NIH), have been detected by MRI. Objective The purpose of this study was to investigate the possibility of including the presence of UBOs as a diagnostic criterion for NF1 in children. Materials and methods The study included 88 children between the ages of 2 and 18 years. The case group consisted of 40 children diagnosed with sporadic or familial NF1 according to the criteria established by the NIH. A control group consisted of 48 individuals referred for routine MRI of the brain for other complaints not related to NF1. Results UBOs were identified in 70% of the NF1 patients and in none of the control group. The sensitivity of the presence of UBOs for the diagnosis of NF1 was 70% (CI 53–83%), with a false-negative rate of 30% (CI 27–47%), a specificity of 100% (CI 86–100%) and a false-positive rate of 0% (CI 0–14%). Conclusion Faced with the difficulties in diagnosing NF1 in children and the high frequency and specificity of the presence UBOs identified by MRI in our series, we rec- ommend the inclusion of the presence UBOs as a diagnostic criterion for NF1 in children. Keywords Neurofibromatosis type 1 . MRI . Unidentified bright objects . Brain . Children Introduction Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder. The estimated incidence of NF1 is 1:3,000 newborns. It is characterized clinically by café-au-lait spots, freckling, Lisch nodules, neurofibromas, optic gliomas, and bone lesions [1–6]. Specific lesions detected in the brain by MRI that are not included in the diagnostic criteria for NF1 [7] have been denominated unidentified bright objects (UBOs) and correspond to increased T2- signal intensity without a mass effect or contrast enhancement, and are most often found in the cerebellum, brainstem and basal ganglia [8–10]. UBOs are present in 43–93% of children with NF1 [9, 11, 12] and are characteristically absent in the first 2 years. They increase in number and size until the age of 12 years, and are rarely seen in patients older than 20 years [13–15]. Considering the difficulty in diagnosing NF1 in children as a result of the infrequency of clinical signs in the first years of life, the purpose of this study was to investigate the possibility of including the presence of UBOs as a diagnostic criterion for NF1 in children. Materials and methods The study population comprised 88 children aged 2– 18 years who were prospectively evaluated from January 2004 to January 2006. The patients, of both genders, were divided into two groups. The case group consisted of 40 children with at least two diagnostic criteria as established Pediatr Radiol (2008) 38:305–310 DOI 10.1007/s00247-007-0712-x J. R. Lopes Ferraz Filho (*) : M. P. Munis : A. Soares Souza : R. A. Sanches Imaging Department, Medical School in São José do Rio Preto, Av. Brigadeiro Faria Lima 5544, São Pedro, São José do Rio Preto, São Paulo 15090000, Brazil e-mail: jrl.ferraz@terra.com.br E. M. Goloni-Bertollo : E. C. Pavarino-Bertelli Center of Research and Attendance in Neurofibromatosis, São Paulo, Brazil