18F-FDG PET and MRS of the early stages of subacute sclerosing panencephalitis in a child with a normal initial MRI.

In subacute sclerosing panencephalitis (SSPE), conventional MRI findings have been reported. However, in the early clinical stages, imaging studies can appear normal. Moreover, with no history of infant measles infection, the diagnosis of SSPE can only be arrived at after extensive investigation that must eliminate a number of neurodegenerative diseases. We report here on (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) and magnetic resonance spectroscopy (MRS) findings in a 14-year-old girl with a normal initial MRI who had not contracted measles. Although (18)F-FDG PET and MRS are not specific or diagnostic for SSPE, these techniques can demonstrate substantial metabolic impairments when MRI findings show no obvious abnormalities, as is often the case in the early stages of this disease.