Abstract for presentation at 38th Annual Scientific Meeting of the Australian and New Zealand Society of Nuclear Medicine 2008

Cerebral FDG-PET Scans in Children with Neurofibromatosis Type 1: Visual and Semi-Quantitative Analysis

  • Dr Kevin London, Department of Nuclear Medicine, The Children's Hospital, Westmead, Australia
  • Dr Mahendranath Moharir, Department of Neurogenetics, The Children's Hospital, Discipline of Paediatrics and Child Health, University of Sydney, Australia
  • Prof Robert Howman-Giles, Department of Nuclear Medicine, The Children's Hospital, Westmead and Discipline of Imaging, University of Sydney, Australia
  • Prof Kathryn North, Department of Neurogenetics, The Children's Hospital, Discipline of Paediatrics and Child Health, University of Sydney, Australia

    • Cognitive and neuropsychological impairment occurs frequently in neurofibromatosis type 1 (NF1). Cerebral MRI abnormalities occur in adults and children with NF1 and FDG-PET studies may also be abnormal. No significant data is available in children with NF1. FDG-PET scans in children with NFI were compared to a cohort of normal controls.
    A retrospective review of FDG-PET cerebral scans in 11 children with NF1 were analysed qualitatively by visual assessment of uptake patterns, and semi-quantitatively by regional SUV analysis of the sub-cortical white matter, basal ganglia and cerebellar cortex. Control studies (n=8) were obtained prospectively from children undergoing initial FDG-PET studies for non-CNS tumours or for non-oncological indications. Subjective comparison of cortical FDG uptake was made. Regional SUV max values were compared using the Mann-Whitney U test.
    Results: Mixed patterns of regional cortical hypometabolism were seen throughout the cerebral hemispheres and basal ganglia. No consistent abnormal pattern was apparent. Thalamic metabolism was more consistently reduced. Statistical comparison showed the left thalamus to have significantly lower tracer uptake in NF1 compared to controls (median SUVmax 7.56 and 8.81 respectively, p=0.048). The right thalamus had a difference approaching significance in NF1 compared to controls (median SUVmax 7.30 and 8.44 respectively, p=0.069). There was no significant difference in FDG uptake in the other regions.
    Conclusion: In children with NF1 there are significant hypometabolic abnormalities seen the cerebral hemispheres and basal ganglia. There was no consistent pattern of abnormal cortical metabolic activity, however thalamic metabolic activity is significantly lower than in controls.

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