Two-phase [11C]L-methionine PET in childhood brain tumors

Pediatr Neurol. May-Jun 1990;6(3):163-70. doi: 10.1016/0887-8994(90)90057-8.


Thirteen children (1.8-15.8 years of age) with brain tumors were studied with [11C]L-methionine positron emission tomography (METPET). Patients were injected intravenously with tracer before a baseline PET scan was obtained. To assess the sensitivity of [11C]L-methionine uptake to competitive inhibition, 10 patients received oral L-phenylalanine (100 mg/kg); 1 hour later, a second METPET was obtained. Subjective assessment of [11C]L-methionine uptake closely paralleled results of quantitative examination (r = 0.81). [11C]L-methionine uptake in tumor-containing brain was increased in 11 patients (mean ratio of [11C] radioactivity in tumor to normal brain: 1.5 +/- 0.57; range: 1.13-2.98). Increased tracer uptake occurred in ependymomas (3), medulloblastoma (1), and astrocytomas (5), but was less intense in low-grade tumors. L-phenylalanine reduced L-methionine uptake (25-69%) in 70% of studies. L-methionine uptake was not sensitive to competitive inhibition in brain radiation injury. Two-phase METPET is of potential value in difficult clinical situations evident in children with brain tumors, including the differential diagnosis of tumor recurrence and cerebral radiation injury.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Astrocytoma / diagnostic imaging*
  • Brain Neoplasms / diagnostic imaging*
  • Child
  • Child, Preschool
  • Diagnosis, Differential
  • Ependymoma / diagnostic imaging*
  • Female
  • Humans
  • Infant
  • Male
  • Medulloblastoma / diagnostic imaging*
  • Methionine
  • Neoplasm Recurrence, Local / diagnostic imaging
  • Phenylalanine
  • Radiation Injuries / diagnostic imaging
  • Sensitivity and Specificity
  • Tomography, Emission-Computed / methods*


  • Phenylalanine
  • Methionine