Last modified: 2014-04-03
Abstract
Introduction: Both gray and white matter pathology, including neuroinflammation, have been incriminated in the pathogenesis of multiple sclerosis (MS), though not-much is known about brain inflammatory changes in pediatric MS population. Increased expression of translocator protein (TSPO) imaged by positron emission tomography (PET) can detect neuroinflammation, mediated by activated microglia, in normal-appearing white matter and cortex in adults with MS. Therefore, we applied PET imaging using the TSPO radiotracer (11)C-[R]-PK11195 (PK PET) in children with MS.
Methods: PK PET was performed in 8 children (age: 10-18 years) with MS associated with typical cerebral MRI findings. The PET images were evaluated by calculating the regional binding potential, based on a simplified reference region model, and the values were compared to a pediatric PET database (Kumar et al., J Neuroinflammation, 2012) to identify brain regions with neuroinflammation.
Results: All but one child showed regions with increased binding on PET, affecting individually variable regions including thalamus (n=4), whose values were also increased bilaterally on the group level; increases were also seen in centrum semiovale (n=2), lentiform nucleus (n=2), frontal (n=3) and parietal cortex (n=2), brainstem (n=2), and cingulate (n=1); some of which were not detected on MRI. Focal areas with increased binding were more restricted than MRI abnormalities, likely representing PK uptake in active lesions only.
Conclusions: PET imaging of activated microglia can detect areas of neuroinflammation in both gray and white matter in children with MS, and may identify regions with active disease thus complementing clinical MRI.