Center for Molecular and Genomic Imaging


Radiochemistry / Cyclotron

The Radiochemistry and Cyclotron Facility produces radioactive targeting molecules for PET imaging studies.

Services offered:

  • • We produce a menu of PET tracers which are not commercially available.
  • • We perform custom syntheses of novel PET tracers
  • • Our on-site cyclotron allows production on demand of PET radionuclides 18F, 11C, 13N, and 15O
  • • The PET radionuclides 64Cu and 89Zr are also available from third party vendors
  • 99mTc SPECT tracers are also available

Radionuclides

The most commonly used PET radionuclides are 18F and 11C, which are produced on site. Longer lived 64Cu and 89Zr, available every 1-2 weeks, are better matched to the longer uptake and residence times of higher molecular weight PET probes such as antibodies, peptides, and nanoparticles.

PET RADIONUCLIDE PROPERTIES

Radionuclide Half-Life Decay Mode(s) Availability
18F 110 min β+ Daily on site
11C 20 min β+ Daily on site
13N 10 min β+ Daily on site
15O 2 min β+ Daily on site
64Cu 12.7 h β+ and β- Every 2 weeks by supplier
89Zr 78.4 h β+, EC, γ Weekly by supplier

PET Radiotracers Available at CMGI

PET uses F-18- or C-11-substituted analogs of small molecules that are involved in biochemical processes, to elucidate image tissue perfusion, metabolism, drug/receptor interactions, and gene expression in vivo. For example, [18F]Fluorodeoxyglucose, an analog of glucose, is used to image areas of high metabolism, such as rapidly proliferating tumors. Targeting molecules may also be covalently conjugated to a metal binding chelating agent, such as TETA or desferrioxamine, to be radiolabeled with 64Cu or 89Zr, respectively, for PET imaging.

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[18F]Fluoride

[18F]Fluoride in aqueous solution is used primarily to image bone and therefore can provide information on features of the skeleton.

Half life 110 minutes; available daily.

[18F]FDG

[18F]Fluorodeoxyglucose, one of the most commonly used PET tracers, is used to measure tissue glucose metabolism. It has important diagnostic and research applications in oncology, neurology, and cardiology.

Half life 110 minutes; available daily.

[18F]FHBG

9-(4-[18F]Fluoro-3-hydroxymethylbutyl) guanine is a reporter probe for the herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene, which is transfected into malignant cells in experimental suicide gene therapy.

Half life 110 minutes; available daily.

[18F]FLT

[18F]Fluorothymidine is a marker for cell proliferation that is more selective for tumor imaging than [18F]FDG.

Half life 110 minutes; available daily.

[18F]FMISO

[18F]Fluoromisonidazole is used for the detection of hypoxia in tumors, myocardial infarcts, or cerebral ischemia.

Half life 110 minutes; available daily.

[11C]Raclopride

[11C]Raclopride is a widely used PET tracer for measurement of D2 dopamine receptor binding characteristics.

Half life 20 minutes; available daily.

[11C]SCH23390

[11C]SCH23390 is used to measure D1 dopamine receptor binding characteristics.

Half life 20 minutes; available daily.

[11C]PK11195

[11C]PK11195 is used to measure microglial activation, associated with various neurodegenerative and neuroinflammatory diseases.

Half life 20 minutes; available daily.

[64Cu]Cu-PTSM

[64Cu]Cu-pyruvaldehyde-bis[N4-methylthiosemicarbazone] is a tracer for blood flow, hypoxia, and cell binding studies.

Half life 12.7 hours; available every two weeks. Please inquire for specific dates.

64Cu- and 89Zr-labeled proteins, peptides, and high MW probes (above)

Relatively long-lived 64Cu (half life 12.7 hours) and 89Zr (78.4 hours) are well matched to the longer uptake and residence times of higher molecular weight probes such as antibodies, peptides, and nanoparticles.

[64Cu]Cu-TETA-conjugates

(shown):The molecular probe is conjugated to the chelating (metal binding) agent TETA, which binds 64Cu.

Half life 12.7 hours; available every two weeks. Please inquire for specific dates.

[89Zr]Zr-desferal-conjugates The molecular probe is conjugated to the chelating agent desferrioxamine, which binds 89Zr.

Half life 78.4 hours; available weekly.

Equipment at the Facility

The Radiochemistry facility is equipped to produce radionclides and prepare PET tracers by automated and manual synthesis.

  • An 11 Mev cyclotron (Siemens RDS111) is used to produce 18F, 11C, 13N, and 15O.
  • • Radionuclides are delivered directly to shielded hot cells, in which radiochemical reactions are performed. The hot cells are shielded with 3 inches of lead and 9 inch leaded glass windows.
  • • Two hot cells are equipped with remote manipulators, to perform manual reactions.
  • Automated synthesis units for 18F and 11C chemistry are used for routine syntheses.

Above: The radiochemistry laboratory includes shielded hot cells, remote manipulators, and automated synthesis units for PET radiopharmaceutical production

Right: Automated synthesis units are used for routine production of 18F and 11C PET tracers.

Novel Radiochemistry and Custom Synthesis

4-[18F]fluorobenzoic acid (FBA) and 2-[18F]fluoropropionic acid (FPA) are used as building blocks for the synthesis of complex molecules such as [18F]-fluoropaclitaxel and as a prosthetic groups for the labeling of peptides and proteins. The synthesis of FBA has been automated.

Peptides may be site-specifically radiolabeled in the solid phase with 18F via FBA or FPA. In cases where solution-phase labeling is preferred, Cu catalyzed 1,3-dipolar Huigen’s cycloaddition (“click” chemistry) is used. Peptides may also be conjugated to a chelating (metal binding) agent for radiolabeling with 64Cu or 89Zr.

Solid phase peptide labeling using 4-[18F]fluorobenzoic acid (FBA).

“Click” chemistry for radiolabeling of peptides with [18F]fluoroalkynes.