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Evaluation of children with craniopharyngioma using carbon-11 methionine PET prior to proton therapy.

ABSTRACT: Fluorine-18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited in its evaluation of brain tumors due to the high basal activity of the cerebral cortex and white matter. Carbon-11 methionine ((11)C MET) has little uptake under normal conditions. We prospectively investigated the uptake of (18)F FDG and (11)C MET PET in patients with craniopharyngioma prior to proton therapy.Ten patients newly diagnosed with craniopharyngioma underwent PET imaging using (18)F FDG and (11)C MET. PET and MRI studies were registered to help identify tumor volume. Measurements of maximum standardized uptake value (SUV(max)) were taken of the tumor and compared with noninvolved left frontal background white matter using a paired t-test. Uptake was graded using a 4-point scale.Median patient age was 9 years (range 5-19). Seven patients were diagnosed by pathology, 1 by cyst fluid aspiration, and 2 by neuroimaging. Median FDG SUV(max) for tumor and background were 2.65 and 3.2, respectively. Median MET SUV(max) for tumor and background were 2.2 and 1, respectively. There was a significant difference between MET tumor SUV(max) and MET background SUV(max) (P = .0001). The difference between FDG tumor SUV(max) and FDG background SUV(max) was not significant (P = .3672).(11)C MET PET uptake is significantly greater within the tumor compared with noninvolved background white matter, making it more useful than FDG PET in identifying active tumor in patients with craniopharyngioma. Future work will focus on using (11)C MET PET to discriminate between active and inactive tumor after irradiation.

SUBMITTER: Laser BS

PROVIDER: S-EPMC3607263 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Evaluation of children with craniopharyngioma using carbon-11 methionine PET prior to proton therapy.

Laser Benjamin S BS Merchant Thomas E TE Indelicato Daniel J DJ Hua Chia-Ho CH Shulkin Barry L BL Snyder Scott E SE

Neuro-oncology 20130213 4

<h4>Background</h4>Fluorine-18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited in its evaluation of brain tumors due to the high basal activity of the cerebral cortex and white matter. Carbon-11 methionine ((11)C MET) has little uptake under normal conditions. We prospectively investigated the uptake of (18)F FDG and (11)C MET PET in patients with craniopharyngioma prior to proton therapy.<h4>Methods</h4>Ten patients newly diagnosed with craniopharyngioma underwent ...[more]

PMID: 23408862

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Project description:The role of metabolic imaging in the diagnosis, treatment, and response assessment of diffuse intrinsic pontine glioma (DIPG) is poorly defined. We investigated the uptake of 11C-methionine in pediatric patients with newly diagnosed DIPG and evaluated the associations of 11C-methionine PET metrics with conventional MRI indices and survival outcomes. Methods: Twenty-two patients with newly diagnosed DIPG were prospectively enrolled on an institutional review board-approved investigational study of 11C-methionine PET. All patients underwent baseline 11C-methionine PET/CT, and initial treatment-response scans after chemotherapy or radiation therapy were obtained for 17 patients. Typical and atypical DIPGs were assessed clinically and radiographically and defined by multidisciplinary consensus. Three-dimensional regions of interest, reviewed by consensus between a nuclear medicine physician and a radiation oncologist, were delineated after coregistration of PET and MR images. Associations of 11C-methionine uptake intensity and uniformity with survival, along with associations between 11C-methionine uptake and conventional MRI tumor indices over time, were evaluated. 11C-methionine PET voxel values within regions of interest were assessed as threshold values across proportions of the study population, and 11C-methionine uptake at baseline was assessed relative to MRI-defined tumor progression. Results: 11C-methionine uptake above that of uninvolved brain tissue was observed in 18 of 22 baseline scans (82%) and 15 of 17 initial response scans (88%). 11C-methionine avidity within MRI-defined tumor was limited in extent, with 11 of 18 positive baseline 11C-methionine PET scans (61%) showing less than 25% 11C-methionine-avid tumor. The increase in total tumor volume with 11C-methionine PET was relatively limited (17.2%; interquartile range, 6.53%-38.90%), as was the extent of 11C-methionine uptake beyond the MRI-defined tumor (2.2%; interquartile range, 0.55%-10.88%). Although baseline 11C-methionine PET intensity and uniformity metrics did not correlate with survival outcomes, initial 11C-methionine avidity overlapped with recurrent tumor in 100% of cases. A clinical diagnosis of atypical DIPG was associated with borderline significantly prolonged progression-free survival (P = 0.07), yet 11C-methionine PET indices at diagnosis did not differ significantly between atypical and typical DIPGs. Conclusion: Most newly diagnosed DIPGs are successfully visualized by 11C-methionine PET. Baseline 11C-methionine uptake delineates regions at increased risk for recurrence, yet intensity and uniformity metrics did not correlate with treatment outcomes in children with DIPG in this study.

Project description: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.

Project description:The purpose of this study was to determine radiation dose effect on the structural integrity of cerebral white matter in craniopharyngioma patients receiving surgery and proton therapy.Fifty-one patients (2.1-19.3 years of age) with craniopharyngioma underwent surgery and proton therapy in a prospective therapeutic trial. Anatomical magnetic resonance images acquired after surgery but before proton therapy were inspected to identify white matter structures intersected by surgical corridors and catheter tracks. Longitudinal diffusion tensor imaging (DTI) was performed to measure microstructural integrity changes in cerebral white matter. Fractional anisotropy (FA) derived from DTI was statistically analyzed for 51 atlas-based white matter structures of the brain to determine radiation dose effect. FA in surgery-affected regions in the corpus callosum was compared to that in its intact counterpart to determine whether surgical defects affect radiation dose effect.Surgical defects were seen most frequently in the corpus callosum because of transcallosal resection of tumors and insertion of ventricular or cyst catheters. Longitudinal DTI data indicated reductions in FA 3 months after therapy, which was followed by a recovery in most white matter structures. A greater FA reduction was correlated with a higher radiation dose in 20 white matter structures, indicating a radiation dose effect. The average FA in the surgery-affected regions before proton therapy was smaller (P=.0001) than that in their non-surgery-affected counterparts with more intensified subsequent reduction of FA (P=.0083) after therapy, suggesting that surgery accentuated the radiation dose effect.DTI data suggest that mild radiation dose effects occur in patients with craniopharyngioma receiving surgery and proton therapy. Surgical defects present at the time of proton therapy appear to accentuate the radiation dose effect longitudinally. This study supports consideration of pre-existing surgical defects and their locations in proton therapy planning and studies of treatment effect.

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Evaluation of children with craniopharyngioma using carbon-11 methionine PET prior to proton therapy.

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Evaluation of children with craniopharyngioma using carbon-11 methionine PET prior to proton therapy.

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