Technetium-99m ECD: a new brain imaging agent: in vivo kinetics and biodistribution studies in normal human subjects
Lipophilic neutral /sup 99m/Tc complexes of diaminedithiol (DADT) ligands cross the brain-blood barrier. A new derivative of DADT family, /sup 99m/Tc ethyl cysteinate dimer (ECD) showed high brain uptake in nonhuman primates. We report here the in vivo kinetics and biodistribution results in 16 normal human subjects. Dynamic images of brain obtained for 10 min following an i.v. administration of (/sup 99m/Tc)ECD showed that the maximum /sup 99m/Tc brain activity reached within 1 min and remained near that level for the next 10 min. The blood clearance of the tracer was very rapid and the activity remaining in blood after 5 min was less than 10%. Within 2 hr 50% of /sup 99m/Tc activity was excreted in urine. Anterior and posterior total-body images were obtained at 5, 30, 60 min, 2, 4, 24, and 48 hr using a moving table at 20 cm/min. Percent injected dose was calculated for different organs and tissues. The brain uptake was 6.5 +/- 1.9% at 5 min postinjection and remained relatively constant over several hours. Two-compartment analysis of brain time-activity curve showed that 40% of brain activity washed out faster (T 1/2 = 1.3 hr) while the remaining 60% had a slower clearance rate (T 1/2 = 42.3 hr). Some of the tracer was excreted through the hepatobiliary system. Lung uptake and retention of (/sup 99m/Tc)ECD was negligible. Radiation dosimetry is favorable for the administration of up to 20-40 mCi of (/sup 99m/Tc)ECD. These results show that (/sup 99m/Tc)ECD is rapidly extracted and retained by the brain providing favorable conditions for single photon emission computed tomography imaging.
- Research Organization:
- Mount Sinai Medical Center, New York, NY (USA)
- OSTI ID:
- 6078793
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 30:5
- Country of Publication:
- United States
- Language:
- English
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RADIOPHARMACEUTICALS
EVALUATION
BIOCHEMICAL REACTION KINETICS
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ISOMERIC NUCLEI
LIGANDS
ORGANOMETALLIC COMPOUNDS
POSITRON COMPUTED TOMOGRAPHY
RADIATION DOSES
TECHNETIUM 99
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BETA-MINUS DECAY RADIOISOTOPES
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DRUGS
EMISSION COMPUTED TOMOGRAPHY
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
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KINETICS
LABELLED COMPOUNDS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
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ORGANS
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TECHNETIUM ISOTOPES
THIOLS
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YEARS LIVING RADIOISOTOPES
550601* - Medicine- Unsealed Radionuclides in Diagnostics