Cerebral glucose metabolism in neurofibromatosis type 1 assessed with [18F]-2-fluoro-2-deoxy-D-glucose and PET.

Abstract

Cerebral PET with [18FJ-2-fluoro-2-deoxy-D-glucose has been performed in four patients with neurofibromatosis type 1 (NF1) to assess the relation between cerebral metabolic activity, MRI, and the presence of neurological symptoms, including seizures, as well as mental and language retardation. Widespread hypometabolism occurred in three of the patients. The lesions on MRI, which were localised in the subcortical white matter and grey structures, had normal rates of glucose metabolism. This finding suggests that the abnormalities seen on MRI are not due to defective blood supply, localised oedema, or grey matter heterotopic foci as previously hypothesised. The presence of the hypometabolic areas seems to be inconsistently related to the occurrence of seizures and is not proportional to the degree of mental impairment. This study provides evidence of a widespread cerebral hypometabolism that is not related to the presence of MRI abnormalities; conversely normal metabolism was present in the areas with an abnormal 1RI signal.

Correlation Between Unidentified Bright Objects on Brain Magnetic Resonance Imaging (MRI) and Cerebral Glucose Metabolism in Patients with Neurofibromatosis Type 1

“…Balestri et al previously suggested that UBOs and hypometabolism in brain PET images were independent and distinctive features of NF1 because metabolic activity was normal in areas that appeared to be abnormal on MRI. 10) Our study findings are consistent with their report, and we reproduced their findings in a relatively large number of subjects (75 patients). To further clarify the role of UBOs and thalamic glucose hypometabolism in NF1, a prospective longitudinal study with a larger number of subjects and with systemic assessment of neuropsychological function is required.…”

“…A hypometabolic pattern has been reported in several studies of brain PET images of patients with NF1. 9,10) Therefore, it is possible that there is a relationship between cerebral hypometabolism and cognitive impairment in patients with NF1. 10) North et al suggested that the pathogenesis of the neurological deficit in patients with NF1 was as follows:…”

Reduced Cerebral Arterial Spin-Labeled Perfusion in Children with Neurofibromatosis Type 1

“…36 A study of 20 adults with NF-1 also showed reduced FDG-PET metabolism in the thalamus, and to a lesser degree, in the cerebellum. In these studies, the extent of abnormal cerebral metabolism did not correlate with the presence or number of UBOs, 35,37 degree of cognitive impairment, 35 or differences in age or sex, 37 similar to the present study.…”

“…Prior FDG-PET studies in NF-1 [35][36][37] have shown abnormal cerebral metabolism similar in distribution to the perfusion pattern noted in this study, for example, global hypometabolism with a more marked hypometabolism in the posterior brain regions. For example, in 4 adolescents with NF-1 (9 -20 years of age), global hypometabolism with a more marked reduction of FDG activity in the thalamus and the occipital lobes was noted with intact metabolism in the striatum.…”

“…For example, in 4 adolescents with NF-1 (9 -20 years of age), global hypometabolism with a more marked reduction of FDG activity in the thalamus and the occipital lobes was noted with intact metabolism in the striatum. 35 Another study of 10 children with NF-1 (4 -15 years of age) observed heterogeneously decreased cortical FDG uptake. Although regional cerebral metabolic differences were not quantitatively analyzed in that study, profound hypometabolism in the thalamus was observed.…”