Two-phase [11C]L-methionine PET in childhood brain tumors.
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.
O'Tuama
L A
LA
Department of Radiology, Johns Hopkins Hospital, Baltimore, Maryland.
Phillips
P C
PC
Strauss
L C
LC
Carson
B C
BC
Uno
Y
Y
Smith
Q R
QR
Dannals
R F
RF
Wilson
A A
AA
Ravert
H T
HT
Loats
S
S
D000293:Adolescent; D001254:Astrocytoma / Q000000981:diagnostic imaging*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004806:Ependymoma / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008527:Medulloblastoma / Q000000981:diagnostic imaging*; D008715:Methionine; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D010649:Phenylalanine; D011832:Radiation Injuries / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed / Q000379:methods*
D010649:Phenylalanine; D008715:Methionine