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.
Department of Radiology, Johns Hopkins Hospital, Baltimore, Maryland.
L A
LA
O'Tuama
P C
PC
Phillips
L C
LC
Strauss
B C
BC
Carson
Y
Y
Uno
Q R
QR
Smith
R F
RF
Dannals
A A
AA
Wilson
H T
HT
Ravert
S
S
Loats
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