European journal of nuclear medicine and molecular imaging
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Eur. J. Nucl. Med. Mol. Imaging · Nov 2003
Comparative Study Clinical Trial Controlled Clinical TrialRegional differences between 99mTc-ECD and 99mTc-HMPAO SPET in perfusion changes with age and gender in healthy adults.
A number of studies using single-photon emission tomography (SPET) have shown perfusion changes with age in several cortical and subcortical areas, which might distort the results of perfusion imaging studies of neuropsychiatric disorders. Technetium-99m labelled ethyl cysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO) are both used as markers of cerebral perfusion, but have different pharmacokinetics and retention patterns. The aim of this study was to determine whether age and gender effects on perfusion SPET differ depending on whether (99m)Tc-HMPAO or (99m)Tc-ECD is used. ⋯ An area in the right anterior frontal lobe showed an increase in perfusion with age only in the HMPAO group, whereas areas in the bilateral retrosplenial cortex showed decreases in perfusion with age only in the ECD group; neither group showed corresponding changes in the grey matter. The present study shows that different effects of age on perfusion are observed depending on whether (99m)Tc-HMPAO and (99m)Tc-ECD is used. This suggests that the results of perfusion SPET are differently confounded depending on the tracer used, and that perfusion SPET with these tracers has limitations when used in research on subtle perfusion changes.
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Eur. J. Nucl. Med. Mol. Imaging · Nov 2003
Comparative StudyReduction of 99mTc-sestamibi and 99mTc-tetrofosmin uptake in MRP-expressing breast cancer cells under hypoxic conditions is independent of MRP function.
Hypoxia reduces the uptake of technetium-99m sestamibi (MIBI) in human cancer cell lines. In the current investigation, we attempted to identify the relationship between hypoxia-induced alteration of (99m)Tc-MIBI accumulation and expression of multi-drug resistance-associated protein (MRP) in the MCF7/WT breast cancer cell line and its subclonal cell line, MCF7/VP, which expresses high levels of MRP1. A second cationic compound, (99m)Tc-tetrofosmin (TF), was also examined. ⋯ Cell binding assay with iodine-125-labelled anti-MRP1 antibody demonstrated its specific binding to MCF7/VP cells. Hypoxia did not affect the amount of antibody bound to MCF7/VP cells. These results indicate that hypoxia-induced reduction of tracer uptake in tumour cells is a phenomenon independent of MRP function.