Postoperative cerebral glucose metabolism in pediatric patients receiving proton therapy for craniopharyngioma

J Neurosurg Pediatr. 2015 Nov;16(5):567-573. doi: 10.3171/2015.4.PEDS159. Epub 2015 Aug 21.


OBJECT The aim of the study was to document postoperative cerebral glucose distribution before proton therapy using F-18 fluorodeoxyglucose positron emission tomography (FDG PET) in children with craniopharyngioma. METHODS Between August 2011 and April 2014, 50 patients (20 males, 30 females) enrolled in a prospective trial for craniopharyngioma underwent FDG PET imaging before proton therapy. Proton therapy was delivered using doublescattered beams with a total prescribed dose of 54 cobalt gray equivalent. Tracer uptake in each of 63 anatomical regions was computed after warping PET images to a 3D reference template in Talairach coordinates. Regional uptake was deemed significantly low or high if it exceeded age-corresponding 95% prediction intervals of the normal population. The reference group included 132 children with non-CNS-related diseases and normal-appearing cerebral FDG PET scans. RESULTS Median patient age at diagnosis was 8.5 years (range 2-18 years). Forty-eight patients underwent 1-4 tumor-related surgeries before proton therapy, including placement of an Ommaya reservoir in 14 patients. Sixteen patients had symptomatic hydrocephalus that was treated with temporary (external ventricular drain, n = 16) or permanent CSF shunting (ventriculoperitoneal shunt, n = 1). The most commonly seen PET abnormalities in patients before proton therapy were significantly reduced uptake in subregions of the frontal lobe (often involving more than 1 gyrus), medial and ventral portions of the temporal lobe, cingulate gyrus, and caudate nucleus. A significantly high uptake was frequently observed on the contralateral side, including the superior, medial, and inferior temporal gyri and a large portion of the parietal lobe. Statistically significant predictor variables identified in the multivariate analysis for the extent of hypometabolism were sex (p = 0.005), hydrocephalus (p = 0.026), and the number of tumor-related surgeries (p = 0.017). CONCLUSIONS Postoperative FDG PET of patients with craniopharyngioma revealed metabolic abnormalities in specific regions of the brain. The ability to identify anatomical metabolic defects in individual patients facilitates the investigation of brain injury in children with craniopharyngioma.

Keywords: CGE = cobalt gray equivalent; EVD = external ventricular drain; FDG PET = F-18 fluorodeoxyglucose positron emission tomography; SUV = standard uptake value; VP = ventriculoperitoneal; craniopharyngioma; oncology; positron emission tomography; proton therapy; surgery.