Retinoblastoma: CT and MR Imaging

Computed tomography (CT) and magnetic resonance imaging (MRI) were performed in 13 children with retinoblastoma. On CT, retinoblastoma appeared as a calcified mass slightly hyperdense to the vitreous, with variable enhancement ranging from none to moderate. On MRI, the tumors demonstrated hyperintense to the vitreous on Ti weighted images (T1WI) and were hypointense to the vitreous on T2WI. Gadolinium-DTPA enhancement provided only slightly increased signal intensity (SI) of the tumors on T1WI.Calcification was not generally distinguished by MRI, while it was easily identified by CT. Retinal hemorrhage or effusion could be more easily separated from the tumor by MRI than by CT. Optic nerve extension by tumor was better discerned by MRI on gadolinium-DTPA enhanced T1WI with fat suppression techniques. CT remains the primary imaging modality in the diagnosis of retinoblastoma because of its superb ability to detect calcification. MRI may be better in detecting retinal hemorrhage, optic nerve involvement and intracranial metastasis and for follow-up study.