Cerebral FDG Metabolic Pattern in Pediatric Patients with Neurofibromatosis Type 1: A Retrospective Study

Aims: Learning disabilities represent the most significant cause of lifetime morbidity in neurofibromatosis type 1 (NF1) patients. The cognitive phenotype of NF1 pediatric patients is not well understood. The purpose of this study was to examine the cerebral glucose metabolic pattern in NF1 pediatric patients.
Study Design: Retrospective.
Place and Duration of Study: Saint Louis University Hospital, Saint Louis, Missouri, United States, between May 2011 and May 2012.
Methodology: Six NF1 pediatric patients underwent FDG PET/CT including the brain, for evaluation of extracranial neoplasm. Their brain PET images were compared with a pediatric comparison set (21 subjects) using Statistical Parametric Mapping. Significant differences between groups were examined at p<0.001, uncorrected for voxel height and p<0.05, corrected for cluster extent.
Results: Compared with the comparison set, the 6 NF1 patients showed the largest cluster of reduced FDG uptake (3966 voxels) in the medial dorsal nucleus of bilateral thalami. Additional clusters of metabolism in the range from 415 to 926 voxels were noticed in the right cingulate gyrus (Brodmann area (BA) 8 and 24), left occipital lobe (BA 17 and 18) and right fronto-parietal lobe (BA 43).
Conclusion: The FDG reduction of the bilateral thalami is compelling and may be most pathognomonic for NF1. This and other areas of FDG reduction found within the brain may contribute to a better understanding of the NF1 cognitive phenotype.