[Methyl-11C]thymidine positron emission tomography in tumoral and non-tumoral cerebral lesions.
BACKGROUND
No ideal radiopharmaceutical exists for positron emission tomography (PET) that fulfills all clinical requirements for the study of brain tumors.


OBJECTIVE
The usefulness of a recently developed PET tracer, [methyl-11C]thymidine ([methyl-11C]TdR) is explored in brain tumors.


METHODS
Twenty patients with confirmed tumoral and non-tumoral brain lesions were investigated with [methyl-11C] TdR PET. The 11C activity was visually and quantitatively assessed. In two patients, dynamic scans were performed. The PET findings were compared to those of magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and to the final diagnosis.


RESULTS
Eight out of ten patients with confirmed tumoral lesions or tumor recurrence had increased 11C activity within the lesion. In ten non-tumoral lesions no increased 11C uptake was found. The dynamic PET studies showed that [methyl-11C] TdR first acts as a blood flow tracer, but that later on the uptake of 11C activity is due to labeled metabolites, crossing the blood-brain barrier. Increased tracer activity was only observed in tumoral and not in non-tumoral contrast-enhanced lesions on MRI or CT.


CONCLUSIONS
[Methyl-11C] TdR is not a selective PET radiopharmaceutical for brain tumors, but can be used as a tracer for tumoral blood-brain barrier disruption.
De Reuck
J
J
PET Center UZ/RUG, Department of Neurology, University Hospital, Gent, Belgium.
Santens
P
P
Goethals
P
P
Strijckmans
K
K
Lemahieu
I
I
Boon
P
P
Achten
E
E
Lemmerling
M
M
Vandekerckhove
T
T
Caemaert
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000000981:diagnostic imaging; D001812:Blood-Brain Barrier; D001927:Brain Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002540:Cerebral Cortex / Q000000981:diagnostic imaging*; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000000981:diagnostic imaging; D002544:Cerebral Infarction / Q000175:diagnosis / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006406:Hematoma / Q000175:diagnosis / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012680:Sensitivity and Specificity; D015173:Supratentorial Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging; D013936:Thymidine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; C012439:methylthymidine; D013936:Thymidine