Evaluation of a potential generator-produced PET tracer for cerebral perfusion imaging: single-pass cerebral extraction measurements and imaging with radiolabeled Cu-PTSM.
Copper(II) pyruvaldehyde bis(N4-methylthiosemicarbazone) (Cu-PTSM), copper(II) pyruvaldehyde bis(N4-dimethylthiosemicarbazone) (Cu-PTSM2), and copper(II) ethylglyoxal bis(N4-methylthiosemicarbazone) (Cu-ETSM), have been proposed as PET tracers for cerebral blood flow (CBF) when labeled with generator-produced 62Cu (t1/2 = 9.7 min). To evaluate the potential of Cu-PTSM for CBF PET studies, baboon single-pass cerebral extraction measurements and PET imaging were carried out with the use of 67Cu (t1/2 = 2.6 days) and 64Cu (t1/2 = 12.7 hr), respectively. All three chelates were extracted into the brain with high efficiency. There was some clearance of all chelates in the 10-50-sec time frame and Cu-PTSM2 continued to clear. Cu-PTSM and Cu-ETSM have high residual brain activity. PET imaging of baboon brain was carried out with the use of [64Cu]-Cu-PTSM. For comparison with the 64Cu brain image, a CBF (15O-labeled water) image (40 sec) was first obtained. Qualitatively, the H2(15)O and [64Cu]-Cu-PTSM images were very similar; for example, a comparison of gray to white matter uptake resulted in ratios of 2.42 for H2(15)O and 2.67 for Cu-PTSM. No redistribution of 64Cu was observed in 2 hr of imaging, as was predicted from the single-pass study results. Quantitative determination of blood flow using Cu-PTSM showed good agreement with blood flow determined with H2(15)O. This data suggests that [62Cu]-Cu-PTSM may be a useful generator-produced radiopharmaceutical for blood flow studies with PET.
Mathias
C J
CJ
Department of Radiology, Washington University School of Medicine, St. Louis, Missouri.
Welch
M J
MJ
Raichle
M E
ME
Mintun
M A
MA
Lich
L L
LL
McGuire
A H
AH
Zinn
K R
KR
John
E K
EK
Green
M A
MA
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003301:Copper Radioisotopes; D008297:Male; D009942:Organometallic Compounds; D010215:Papio; D013882:Thiosemicarbazones; D014055:Tomography, Emission-Computed
D003301:Copper Radioisotopes; D009942:Organometallic Compounds; D013882:Thiosemicarbazones; C063294:copper (II) ethylglyoxal bis(N(4)-methylthiosemicarbazone); C052629:copper pyruvaldehyde bis(N(4)-methylthiosemicarbazone) complex; C063293:copper (II) pyruvaldehyde bis(N(4)-dimethylthiosemicarbazone)