Technetium-99m p-iodophenethyldiaminodithiol (DADT-IPE): potential brain perfusion imaging agent for SPECT

Area of Science:

• Radiochemistry
• Nuclear Medicine
• Pharmacology

Background:

• Development of novel radiotracers is crucial for advancing diagnostic imaging.
• Technetium-99m (99mTc) labeled compounds are widely used in nuclear medicine.
• Cerebral perfusion imaging requires tracers with specific brain uptake and retention properties.

Purpose of the Study:

• To synthesize and characterize a new N-p-iodophenethyl diaminodithiol (DADT-IPE) ligand.
• To complex DADT-IPE with 99mTc for potential use as a cerebral perfusion imaging agent.
• To evaluate the in vivo performance of the 99mTc-DADT-IPE complex in rats.

Main Methods:

• Synthesis of the DADT-IPE ligand.
• Complexation of DADT-IPE with 99mTc using stannous chloride reduction.
• Separation of 99mTc-DADT-IPE complexes using High-Performance Liquid Chromatography (HPLC).
• Competitive inhibition studies to compare DADT-IPE with N-isopropyl-p-iodoamphetamine (IMP).
• Biodistribution studies of 99mTc-DADT-IPE complexes in rats.

Main Results:

• Two 99mTc-DADT-IPE complexes (a and b) were successfully synthesized and separated.
• DADT-IPE exhibited a competitive inhibition value (IC50) similar to IMP.
• [99mTc-DADT-IPE(a)] showed significant brain uptake (0.65% injected dose at 5 min) and retention (0.53% at 60 min) in rats.
• The brain clearance half-life of [99mTc-DADT-IPE(a)] was determined to be over 5 hours.
• [99mTc-DADT-IPE(b)] demonstrated lower brain uptake and retention compared to complex (a).

Conclusions:

• The novel ligand DADT-IPE can be effectively complexed with 99mTc.
• The complex [99mTc-DADT-IPE(a)] displays favorable characteristics for cerebral perfusion imaging.
• Further investigation is warranted to assess its potential as a clinical diagnostic agent.