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Cellular basis of ECD brain retention
M R Jacquier-Sarlin1, B S Polla, D O Slosman
1Department of Radiology, Geneva University Hospital, Switzerland.
Summary
Esterase activity influences technetium Tc 99m exametazime (ECD) retention in cells. Low membranar and high cytosolic esterase activity optimize ECD uptake, crucial for accurate brain perfusion imaging.
Area of Science:
- Biochemistry
- Cell Biology
- Nuclear Medicine
Background:
- Clinical discrepancies exist between ECD and HMPAO for regional cerebral perfusion.
- These discrepancies are notable in brain tumors and stroke recovery.
- The cellular mechanisms of ECD accumulation require investigation.
Purpose of the Study:
- To investigate the in vitro cellular mechanisms of ECD accumulation.
- To correlate esterase activity with ECD retention at the cellular level.
Main Methods:
- Time course incorporation of ECD was studied in U937, U373, and EaHy926 cell lines.
- Esterase activity (total, membranar, and cytosolic) was measured.
- The effects of diisopropylfluorophosphate (DFP) and temperature on ECD retention were analyzed.
Main Results:
- Significant differences in ECD retention were observed across cell lines.
- ECD retention (%UECD) was inversely correlated with total cellular esterase activity (EATOT).
- Inhibition of cytosolic esterase activity (with DFP) or low temperatures led to increased ECD retention, suggesting passive diffusion.
Conclusions:
- Optimal ECD uptake requires low membranar and high cytosolic esterase activity.
- Cytosolic esterase activity is critical for ECD cell retention.
- Membranar esterase activity should be considered when interpreting unusual ECD-SPECT findings.