Assessment of Cu-ETS as a PET radiopharmaceutical for evaluation of regional renal perfusion

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• 作者：Mark A. Green ; Carla J. Mathias ; Lynn R. Willis ; Rajash K. H ; a ; Jeffrey L. Lacy ; Michael A. Miller ; Gary D. Hutchins
• 关键词：Renal perfusion ; Copper-62 ; Copper-64 ; Cu-ETS radiopharmaceutical ; Positron emission tomography (PET)
• 刊名：Nuclear Medicine and Biology
• 出版年：2007
• 出版时间：April 2007
• 年：2007
• 卷：34
• 期：3
• 页码：247-255
• 全文大小：744 K

文摘

The copper(II) complex of ethylglyoxal bis(thiosemicarbazone) (Cu-ETS) was evaluated as a positron emission tomography (PET) radiopharmaceutical for assessment of regional renal perfusion.

Methods

The concordance of renal flow estimates obtained with 11- and 15-μm microspheres was confirmed in four immature farm pigs using co-injected ⁴⁶Sc- and ⁵⁷Co-microspheres administered into the left ventricle. With the use of both immature farm pigs (n=3) and mature Göttingen minipigs (n=6), regional renal radiocopper uptake following intravenous [⁶⁴Cu]Cu-ETS administration was compared to microsphere measurements of renal perfusion. The distribution and kinetics of [⁶⁴Cu]Cu-ETS were further studied by PET imaging of the kidneys. The rate of [⁶⁴Cu]Cu-ETS decomposition by blood was evaluated in vitro, employing octanol extraction to recover intact [⁶⁴Cu]Cu-ETS.

Results

The co-injected 11- and 15-μm microspheres provided similar estimates of renal flow. A linear relationship was observed between the renal uptake of intravenous [⁶⁴Cu]Cu-ETS and regional renal perfusion measured using microspheres. [⁶⁴Cu]Cu-ETS provided high-quality PET kidney images demonstrating the expected count gradient from high-flow outer cortex to low-flow medulla. When incubated with pig blood in vitro at 37°C, the [⁶⁴Cu]Cu-ETS radiopharmaceutical was observed to decompose with a half-time of 2.8 min.

Conclusion

Cu-ETS appears suitable for use as a PET radiopharmaceutical for evaluation of regional renal perfusion, affording renal uptake of radiocopper that varies linearly with microsphere perfusion measurements. Quantification of renal perfusion (in ml min⁻¹ g⁻¹) with [^60,61,62,64Cu]Cu-ETS will require correcting the arterial input function for the fraction of blood radiocopper remaining present as the intact Cu-ETS radiopharmaceutical, since the Cu-ETS chelate has limited chemical stability in blood. Rapid octanol extraction of blood samples appears suitable as an approach to capturing the actual blood concentration of [^60/61/62/64Cu]Cu-ETS.