New SPECT and PET Radiopharmaceuticals for Imaging Cardiovascular Disease

Table 1

Commercial SPECT Radiotracers for Myocardial Perfusion Imaging.

	^99mTc-Sestamibi (Cardiolite); (i) nonspecific passive diffusion across myocardial membrane proportional to blood flow; (ii) intracellular activity driven by negative transmembrane potential across bilayers of cell sarcolemma and mitochondria; (iii) 90% associated with mitochondria in an energy dependent manner; (iv) almost no redistribution, slow clearance; (v) myocardial uptake is 1.0% of injected dose at rest and; 1.4% at peak stress at 5 minutes; (vi) FDA approved in December 1990
	^99mTc-Tetrofosmin (Myoview); (i) nearly identical to ^99mTc-sestamibi; (ii) 1.2% of injected dose at rest and 1.5% at peak stress at 5 minutes; (iii) FDA approved in February 1996
	^99mTc-Teboroxime (CardioTec); (i) neutral complex, nonspecific passive diffusion across myocardial membrane; (ii) no specific localization in cytosolic or mitochondrial subcellular components; (iii) must image within a few minutes due to high initial extraction (2 min) and rapid washout at high flow; (iv) injured cells have even faster washout; (v) significant binding to RBC; (vi) FDA approved in January 2002 (presently not marketed)