NEUROFIBROMATOSIS TYPE-1 IN CHILDREN - MR-IMAGING AND FOLLOW-UP-STUDIES OF CENTRAL-NERVOUS-SYSTEM FINDINGS

Purpose: To determine the frequency, evolution and diagnostic impact o f characteristic central nervous system MR imaging lesions in children with neurofibromatosis type 1 (NF1). Subjects: We reviewed 89 childre n with established or clinically suspected disease. A final diagnosis of NF1 was made in 72 (age range, 10 months to 14 years). Results. Hyp erintense lesions on long TR images were detected in 78% of patients, principally involving the basal ganglia, cerebellum and brain stem. In 30% of the globus pallidus lesions, hyperintensity was seen on short TR images, being usually isointense on IR T1 weighted images. Globus p allidus lesions did not enhance. Eight patients presented atypical une nhanced lesions showing either edema, mass effect or hypointensity on short TR images; 2 of them were considered symptomatic brain stem glio mas. Six other children showed one or more growing enhanced cerebral l esions classified as tumors. Other child developed a growing enhanced lesion that markedly decreased in the follow-up studies. Twenty patien ts (28%) had optic gliomas. In two children, under 6 years old, this t umor appeared de novo. Forty-five children had several follow-up MR im aging studies (mean interval, 3 years). Regression of the basal gangli a lesions, both in size and/or intensity was noticed in 42% of cases, enlargement or new appearance of lesions in 24.5%, mixed increased/dec reased in 7%, and stability in 26.5%. White matter lesions of the cere bellum and brain stem decreased in size in 40%, grew in 15.5%, showed a mixed increased/decreased pattern in 11%, and remained unchanged in 33.5% of cases. An involutional tendency of these lesions occurred in children older than 10 years, while progression was more frequent in y ounger children (P < 0,05). Conclusions: Hyperintense lesions are high ly prevalent and characteristic in patients with NF1. MR imaging contr ibuted to a definitive diagnosis of NF1 in 53% of suspected cases. Fol low-up studies are necessary in the evaluation of suspected NF1, even if the first examination is negative. (C) 1998 Elsevier Science Irelan d Ltd.