Is faster always better? What is the implication of a shorter time to imaging with tetrofosmin compared to sestamibi?

Excerpt

Myocardial perfusion imaging (MPI) using single photon emission computed tomography (SPECT) was revolutionized by the development and commercial availability of technetium-99m (Tc-99m) labeled radiotracers. For many decades, thallium-201 was the predominant radiotracer utilized for SPECT MPI which, compared to other radiotracers of the time, offered favorable physiologic and biologic characteristics including robust myocardial uptake, rapid blood pool clearance, near-linear relationship between uptake and regional myocardial blood flow for flows less than 2.5mL·min⁻¹·g⁻¹, and myocardial washout and redistribution properties which aided in distinguishing areas of non-viability from ischemic myocardium. However, disadvantages and physical limitations of thallium-201 including a predominant daughter emission (95%) of low energy, easily scattered characteristic x-rays (69 to 81 keV) and a 73.1 hour physical half-life fueled the development of radiotracers with superior properties for gamma camera scintillation imaging and minimizing radiation dose to patients.1 …