Magnetic resonance imaging in the analysis of pediatric orbital tumors: Utility of diffusion-weighted imaging

PURPOSE To identify common radiographic features of pediatric orbital tumors by the use of magnetic resonance imaging (MRI) techniques, diffusion-weighted imaging (DWI), fat saturated T2, and pre- and postgadolinium T1. DWI is hypothesized to help identify and predict the malignancy of specific brain tumors. To our knowledge, a similar analysis in which the authors have used this combination of MRI techniques has not been performed with orbital tumors. METHODS We performed a retrospective chart review of all patients younger than 18 years of age, each diagnosed with an orbital mass lesion, imaged by MRI from 2005 to 2008. The NIR images were analyzed by use of the aforementioned techniques. RESULTS Mass lesions identified in the chart review included rhabdomyosarcoma (n = 4), myofibroma (n = 2), hemangioma (n = 4), lymphangioma (n = 2), neurofibroma (n = 4), Langerhans histiocytosis (n = 2), and one of each of the following: giant cell tumor, meningioma, lymphoid hyperplasia of the lacrimal gland (chronic sclerosing sialadenitis), optic nerve glioma, lipodermoid, and dermoid. DWI was used to differentiate tumors into those with increased diffusion, restricted diffusion, and 3 mixed diffusion pattern. Capillary hemangiomas and rhabdomyosarcomas 2 tumors with potentially overlapping appearances with traditional M RI techniques had contrasting appearances with DNI. CONCLUSIONS DWI can help to distinguish among certain pediatric orbital tumors when combined with traditional MRI techniques. This technique may thus be considered an additional tool to help, refine the differential diagnosis of orbital tumors in children. (J AAPOS 2010;14:257-262)