American Journal of Neuroradiology 2008;29:1006.
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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1018
PEDIATRICS
Citrate in Pediatric CNS Tumors?
From the Department of Radiology (A.P., M.D.N., S.B.), Children's Center for Cancer & Blood Diseases (Z.A.S., J.L.F.), Children's Hospital Los Angeles, Los Angeles, Calif; and Rudi Schulte Research Institute (S.B.), Santa Barbara, Calif.
Please address correspondence to Stefan Blüml, PhD, Children's Hospital Los Angeles, Department of Radiology, MS 81, 4650 Sunset Blvd, Los Angeles, CA 90027; e-mail: sbluml{at}chla.usc.edu
BACKGROUND AND PURPOSE: In a subset of in vivo MR spectra acquired from pediatric brain tumors, we have observed an unassigned peaks. The goal of this study was to determine the molecule of origin, and the prevalence and concentration of this chemical in various pediatric brain tumors.
MATERIALS AND METHODS: Single-voxel point-resolved spectroscopy (PRESS) spectra from 85 patients with brain tumors and 469 control subjects were analyzed. Citrate seemed to be a likely candidate, and model spectra of citrate were added to the basis set of metabolites for automated processing with use of LCModel software. Absolute "apparent" concentrations of citrate and the Cramer-Rao lower bounds (CRLB), indicators for the reliability of detection, were determined.
RESULTS: "Apparent" citrate was detected in 26 of 85 patients with CRLB of less than 25%. Diffuse intrinsic brain stem glioma (DIBSG) had the highest mean concentration (4.0 ± 1.1 mmol/kg in all subjects), and 8 of 12 patients had CRLB less than 25%. A significant reduction of citrate (P < .01) was observed in 6 DIBSGs that had follow-up MR spectroscopy studies after radiation therapy. "Apparent" citrate with CRLB less than 25% was detected in 5 of 22 medulloblastomas (mean citrate, 2.9 ± 2.2 mmol/kg), in 5 of 14 ependymomas (2.6 ± 1.8 mmol/kg), 5 of 14 astrocytomas (1.9 ± 1.2 mmol/kg), and 3 of 23 pilocytic astrocytomas (1.4 ± 1.1 mmol/kg). In control subjects older than 6 months, CRLB less than 25% was not observed, whereas CRLB less than 25% was observed in 39 of 194 subjects younger than 6 months.
CONCLUSION: MR signal intensity consistent with citrate was observed in pediatric brain tumors and in the developing brain of infants younger than 6 months.