Abstract
Copper(II)-pyruvaldehyde bis (N-4-methylthiosemicarbazone) (Cu-PTSM) labelled with 62,64Cu is a promising radiotracer for the study of blood flow using positron emission tomography (PET). We have investigated the application of a simple trapped tracer model to measurements of tissue 64Cu-PTSM uptake combined with continuous arterial sampling. A dual-tracer method was used to compare blood flow estimated by 64Cu-PTSM with values derived from measurements using cobalt-57 microspheres in the rat. Prolonged retention of 64Cu-PTSM following intravenous administration was initially confirmed in both normal tissues and tumours. After intraventricular 64Cu-PTSM infusion, cumulative arterial 64Cu activity increased progressively, and after extraction in n-octanol was found to plateau to levels corresponding with those reached following administration of 57CO microspheres. Rapid and species-dependent rates of 64Cu-PTSM decomposition to non-extractable 64Cu complexes were found in rat and human blood in vitro (70%±6% and 43%±5% respectively at 16 min), demonstrating the need for immediate processing of arterial samples. Close agreement was found between blood flow estimated by 64Cu-PTSM and 57CO microsphere methods in tissues of low to moderate flow: muscle (0.01, 0.08, 0.07 ml/min per gram; mean difference, mean 64Cu, mean 57Co), brain (0.09, 0.52, 0.43 ml/min per gram) and kidney (−0.16, 2.29, 2.45 ml/min per gram). Estimates of cardiac output also compared favourably between the two methods (5.7, 59.8, 54.1 ml/min). We conclude that a simple tissue trapping model may be suitable for the derivation of blood flow estimates using 62,64Cu-PTSM, PET imaging and continuous arterial blood sampling.
Similar content being viewed by others
References
Zweit J, Goodall R, Cox M, et al. Development of a high performance zinc-62/copper-62 radionuclide generator for positron emission tomography. Eur J Nucl Med 1992;19:418–425.
Green MA. A potential copper radiopharmaceutical for imaging the heart and brain: copper-labeled pyruvaldehyde his (N 4-methylsemicarbazone). Int J Rad Appl Instrum [B] 1987;14:59–61.
Green MA, Klipperstein DL, Tennison JR. Copper (II) bis(thiosemicarbazone) complexes as potential tracers for evaluation of cerebral and myocardial blood flow with PET. J Nucl Med 1988;29:1549–1557.
Levin VA. Relationship of octanol/water partition coefficient and molecular weight to rat brain capillary permeability. J Med Chem 1980;23:682–684.
Shelton ME, Green MA, Mathias CJ, et al. Assessment of regional myocardial and renal blood flow with copper-PTSM and positron emission tomography. Circulation 1990;82:990–997.
Mathias CJ, Welch MJ, Raichle ME, et al. Evaluation of a potential generator-produced PET tracer for cerebral perfusion imaging: single-pass cerebral extraction measurements and imaging with radiolabeled Cu-PTSM. J Nucl Med 1990;31:351–359.
Green MA, Mathias CJ, Welch MJ, et al. Copper-62-labelled pyruvaldehyde bis(N-4-methylthiosemicarbazone) copper (II): synthesis and evaluation as a positron emission tomography tracer for cerebral and myocardial perfusion. J Nucl Med 1990;31:1989–1996.
Mathias CJ, Welch MA, Perry DJ, et al. Investigation of copper-PTSM as a PET tracer for tumour blood flow. Nucl Med Biol 1991;18:807–811.
John EK, Green MA. Structure-activity relationship for metal-labeled blood flow tracers: comparison of keto aldehyde bis(thiosemicarbazonato) copper(II) derivatives. J Med Chem 1990;33:1764–1770.
Barnhardt AJ, Voorhees WD, Green MA. Correlation of Cu(PTSM) localization with regional blood flow in the heart and kidney. Nucl Med Biol 1989;16:747–748.
Heyman MA, Payne BD, Hoffman JIE, et al. Blood flow measurements with radionuclide-labeled particles. Prog Cardiovasc Dis 1977;20:55–78.
Mathias CJ, Bergmann SR, Green MA. Development and validation of a solvent extraction technique for determination of Cu-PTSM in blood. Nucl Med Biol 1993;20:343–349.
Marsden PK, Ott RJ, Bateman JE, et al. The performance of a large-area multiwire proportional chamber positron camera for clinical use. Phys Med Biol 1989;34:1043–1062.
Zweit J, Smith AM, Downey S, et al. Excitation functions for deuteron interactions in natural Ni: production of no-carrier added 64Cu from enriched 64Ni targets for positron emission tomography. Int J Rad Appl Instrum (A) 1991;42:193–197.
Stanek KA, Coleman TG, Smith TL, et al. Two hemodynamic problems commonly associated with the microsphere technique for measuring regional blood flow in rats. J Pharmacol Methods 1985;13:117–124.
Warren DJ, Ledingham JGG. Measurement of cardiac output distribution using microspheres. Some practical and theoretical considerations. Cardiovasc Res 1974;8:570–581.
Leblanc AD, Riley RC, Robinson RG. Simultaneous measurement of total and nutritional coronary blood flow in dogs. Circulation 1974;51:338–347.
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1:307–310.
Herrero P, Markham J, Weinheimer CJ, et al. Quantification of regional myocardial perfusion with generator-produced 62Cu-PTSM and positron emission tomography. Circulation 1993;87:173–183.
Author information
Authors and Affiliations
Additional information
Correspondence to: P. Carnochan
Rights and permissions
About this article
Cite this article
Young, H., Carnochan, P., Zweit, J. et al. Evaluation of copper(II)-pyruvaldehyde bis (N-4-methylthiosemicarbazone) for tissue blood flow measurement usina a trapped tracer model. Eur J Nucl Med 21, 336–341 (1994). https://doi.org/10.1007/BF00176573
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00176573