Radiochemistry of Technetium-99m

Otto C. Boerman, PhD

Radboud University Nijmegen Medical Center, The Netherlands

Radboud University Nijmegen Medical Center, The Netherlands

Radboud University Nijmegen Medical Center, The Netherlands

Radboud University Nijmegen Medical Center, The Netherlands

TechnetiumTechnetium

- 1850: Dimitri Mendeleev: Em- 1846-1908: Ilmenium, Pelopium, Davyum, Nipponium- 1925: Noddack et al.: Masurium- 1937: Perrier & Segre: Panormium τεχνητοζ1937: Perrier & Segre: Panormium, τεχνητοζ

- Oxidation state: 0, 1+, 2+, 4+, 5+, 6+, 7+

5

- 1962: Kenna & Kuroda - pitchblende Congo: 0.2 ng/kg

Technetium-99mTechnetium 99m

• 99mT i t t bl t t f t h ti 99 (99T ) ith• 99mTc is a metastable state of technetium-99 (99Tc) witha half-life of 6.02 hours.

• decay to the ground state of 99Tc: 90% emission ofdecay to the ground state of Tc: 90% emission ofgamma photons of 140 keV

Mo-99

T 99Tc-99m

6

Tc-99

Radiation exposure from Tc 99mRadiation exposure from Tc-99m

• The specific gamma ray constant for Tc-99m is 2 mGy / hour.MBq at 1 cm

• The half-value layer is 0.17 mm lead • C t l f th di ti• Control of the radiation exposure:

reduction factor

0.5 0.1 0.01 0.001 0.0001factormm Pb 0.17 0.8 1.6 2.5 3.3

7

Production of Technetium 99mProduction of Technetium-99m

8

Development of Tc 99m generator at BNLDevelopment of Tc-99m generator at BNL

Powell "Jim" Richards and Walter Tucker

9

Powell Jim Richards and Walter Tucker

Tc-99m generatorTc 99m generator

- Technetium 99m (99mTc) is a decay product of molybdenum-99 (t½ = 66 h)Obt i d b l ti it f l bd 99 t

10

- Obtained by eluting it from a molybdenum-99 generator

Labeling halfproducts with Tc 99mLabeling halfproducts with Tc-99m

• Reduction of TcO4-

• Reductor: Sn2+, Fe2+ TcO4-

• Incubation with halfproduct• Quality control

• Radionuclidic purity: breakthrough of Mo-99740 k V h t 0 5 l d d lib t740 keV photons, 0.5 cm lead, dose calibrator

• ITLC: stationary phase silicagel

TcO2

• ITLC: stationary phase – silicagelmobile phase – 0.1 M ammonium acetate, pH 5.5

Coordination chemistry of Tc 99mCoordination chemistry of Tc-99m

TcO4-

Sn2+

Tc(V)

Square pyrimidal complex

12

Gluconate glucoheptonate

Tc-99m-labeled agents for myocardial perfusionTc 99m labeled agents for myocardial perfusion

99mTc-sestamibi

13

Tc-99m-labeled agents for cerebral perfusionTc 99m labeled agents for cerebral perfusion

14

Tc 99m labeled agents for renal functionTc-99m-labeled agents for renal function

15

Tc 99m demotateTc-99m-demotate

16

Tc-99m-Methylene diphosphonate (MDP)Tc 99m Methylene diphosphonate (MDP)

17

Labeling antibodies peptides and small molecules with Tc 99mLabeling antibodies, peptides and small molecules with Tc-99m

Direct labeling method:

Using free sulfhydril groups of the biomolecule to chelate Tc-99m

(Schwarz method, iminothiolane method)

Bifunctional chelate method:Bifunctional chelate method:

Modification of biomolecule with bifunctional chelating agent

(HYNIC, MAG3, tetraamine, a.o.)

Hybrid method:

Incorporating tripeptide sequence (Gly3, Cys-Gly-Gly, Cys-Gly-Cys) to introduce a

N4, N3S, N2S2 donor set

18

Schwarz method: a direct labeling methodSchwarz method: a direct labeling method

• Incubate Ab with β-ME (1000:1)

30 i RT30 min, RT

• Purify Ab by Gelfiltration

• Add transchelator

(gluconate, MDP, tricine)

• Add TcO4-

• Incubate 10 min, RT

• QC with ITLC

M th & Elli J N l M d 1990 31 692 697

19

Mather & Ellison. J Nucl Med 1990; 31: 692-697

Iminothiolane method: a direct labeling methodIminothiolane method: a direct labeling method

protein protein

Patricio et al Q J Nucl Med 1995; 39: 74-75

20

Patricio et al. Q J Nucl Med 1995; 39: 74-75

Tc 99m labeling via a bifunctional chelate: S MAG3Tc-99m labeling via a bifunctional chelate: S-MAG3

H2N-peptide +0.1 M NaHCO3pH 8.5

Hpeptide-N

TcO4-

RTTricine/tartrate

99TcH

Hnatowich et al J Nucl Med 1998; 39: 56-64 Hpeptide-N

21

Hnatowich et al. J Nucl Med. 1998; 39: 56-64 pep de N

Tc-99m labeling via a bifunctional chelate: S-HYNICg

H2N-peptide + peptide-NH

TcO4-

SnCl2Coligand L

peptide

Tc-99m-Interleukin-8

I t l ki 8Interleukin-8

Tc-99m-Interleukin-8

Interleukin-8

8 h4 h2 h1 h1 min

Tc 99m labeling via HYNIC using different coligandsTc-99m labeling via HYNIC using different coligands

25

Rennen et al. Bioconj Chem. 2002; 13: 370

99mTc-IL-8: Effect of the coligandTc IL 8: Effect of the coligand

Tricine EDDA TPPTS Nicotinic Isonicotinic

Abscess/background ratio:

15 23 4 22 29

The coordination of Tc 99m in HYNIC conjugatesThe coordination of Tc-99m in HYNIC-conjugates

27

King et al. Dalton Trans. 2007; 43:4998-5007.

Tc 99m labeling using the hybrid methodTc-99m labeling using the hybrid method

P483: Ac-Lys-Lys-Lys-Lys-Lys-Cys-Gly-Cys-Gly-Gly-Pro-Leu-Tyr-Lys-Lys-Ile-Ile-Lys-Lys-Leu-Leu-Glu-Ser

Incubate peptide with TcO4- glucoheptonate

0.9% NaCl, 20 min, 95 °C0.9% NaCl, 20 min, 95 C

28

Tc 99m labeling using the hybrid methodTc-99m labeling using the hybrid method

P829: cyclo-(N-Me)Phe-Tyr-D-Trp-Lys-Val-Hcy(CH2CO-β-Dap)-Lys-Cys-Lys-NH2

Incubate peptide with TcO4- glucoheptonate

0.9% NaCl, 20 min, RT

29

Tc 99m labeling using the tricarbonyl methodTc-99m labeling using the tricarbonyl method

Formation of Tc(CO)3(H2O)3 complexLabeling of (modified) peptide with the Tc(CO)3(H2O)3 complex

30

- Alberto, Schibli, Egli, Schubiger. PSI Villigen, ETH Zurich

31

Waibel et al. Nat Biotechnol. 1999 ;17:897-901

Tc-99m labeling using the tricarbonyl methodTc-99m labeling using the tricarbonyl method

Synthesis of 99mTc(CO)3(H2O)3+

Reduce TcO4- with NaBH4 and CO (1 atm), 30 min at 75 °CReduce TcO4 with NaBH4 and CO (1 atm), 30 min at 75 C

or using with Isolink™ kit: K2[H3BCO2], 30 min at 100 °C

32

Tc 99m labeling using the tricarbonyl methodTc-99m labeling using the tricarbonyl method

33

Tc-99m labeling using the tricarbonyl methodTc 99m labeling using the tricarbonyl method

• Label (modified) peptide with Tc(CO)3(H2O)3+ at 2 mg/ml

• Mix 1 : 2 with 0.5 M MES, pH 6.2

• Add 99mTc(CO) (H O) +Add 99mTc(CO)3(H2O)3

• Incubate 15-30 min at 37 °C

• Labeling efficiency: 70-95 %

• Purify the labeled peptide

34

99mTc IL 8 in rabbits with i m E Coli infection99mTc-IL-8 in rabbits with i.m. E.Coli infection

99mTc-HYNIC-IL-8 99mTc(CO)3-IL-8