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Detecting Treatment-Induced Metabolic Abnormalities in Craniopharyngioma Patients Undergoing Surgery and Proton Therapy

C Hua

C Hua1*, B Shulkin1 , D Indelicato2 , F Boop3 , Y Li1 , X Li1 , T Merchant1 , (1) St. Jude Children's Research Hospital, Memphis, TN, (2) University of Florida Proton Therapy Institute, Jacksonville, FL, (3) Semmes-Murphey Neurologic and Spine Institute, Memphis, TN


SU-E-J-122 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To identify treatment-induced defects in the brain of children with craniopharyngioma receiving surgery and proton therapy using fluorodeoxyglucose positron emission tomography (FDG PET).

Methods: Forty seven patients were enrolled on a clinical trial for craniopharyngioma with serial imaging and functional evaluations. Proton therapy was delivered using the double-scattered beams with a prescribed dose of 54 Cobalt Gray Equivalent. FDG 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 exceeding two standard deviations of normal population from the mean. For establishing the normal ranges, 132 children aged 1-20 years with non-central nervous system related diseases and normal-appearing cerebral PET scans were analyzed. Age- and gender-dependent regional uptake models were developed by linear regression and confidence intervals were calculated.

Results: Most common PET abnormality before proton therapy was significantly low uptake in the frontal lobe, the occipital lobe (particularly in cuneus), the medial and ventral temporal lobe, cingulate gyrus, caudate nuclei, and thalamus. They were related to injury from surgical corridors, tumor mass effect, insertion of a ventricular catheter, and the placement of an Ommaya reservoir. Surprisingly a significantly high uptake was observed in temporal gyri and the parietal lobe. In 13 patients who already completed 18-month PET scans, metabolic abnormalities improved in 11 patients from baseline. One patient had persistent abnormalities. Only one revealed new uptake abnormalities in thalamus, brainstem, cerebellum, and insula.

Conclusion: Postoperative FDG PET of craniopharyngioma patients revealed metabolic abnormalities in specific regions of the brain. Proton therapy did not appear to exacerbate these surgery- and tumor-induced defects. In patients with persistent and new abnormalities, continued investigation on clinical symptoms and cognitive outcomes is ongoing to establish the association and predictive values of metabolic imaging.

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