Myocardial perfusion imaging with 99mTc-labeled radiopharmaceuticals: How fast can a stress-rest same-day imaging protocol be completed?

Excerpt

Since its first clinical introduction in the early 1990s, myocardial perfusion imaging (MPI) with either 99mTc-Sestamibi (Cardiolite) or 99mTc-Tetrofosmin (Myoview) has been the subject of several types of imaging protocols.1 Although various parameters must be taken into consideration before establishing a specific imaging protocol, achievement of the highest overall diagnostic accuracy in the safest way for the patient must remain the major goal. In the actual highly “competitive” healthcare environment, obtaining a diagnosis in the easiest, safest, fastest, and less expensive way has almost become mandatory. Most of the non-nuclear cardiologic diagnostic procedures can be completed within 1 hour while a complete same-day MPI protocol still requires a longer time, no matter if a rest-stress or stress-rest injection sequence is used,2 unless a stress-only protocol is performed. Most of the current MPI protocols are modulated from two general parameters: pharmacokinetics of the radiopharmaceuticals and the type of detector-software combination used in the imaging data acquisition and analysis process. In recent years, researches have been focused on the development of dedicated cardiac systems showing potential benefits such as patient comfort, shorter acquisition time, and/or reduced administered activity.3-5 In comparison with the traditional scintillation detector technology, novel detector technology such as pixelated solid-state CZT (an alloy of cadmium telluride and zinc telluride) detectors offers a better energy resolution and a virtually linear count rate response. This new type of detector has demonstrated similar performance as traditional systems, but with significant shorter imaging times or lower administered radioactivity, achieving a reduction in absorbed dose to 1 mSv for a single injection of MPI radiotracer.6 Another variation from traditional design is the upright position offered in some dedicated systems.7 Other camera systems offer a rotating chair instead of a rotating gantry or special detectors to allow for optional x-ray-based attenuation correction. Another upgraded technology uses a conventional multi-purpose SPECT system with a cardio-focal collimator and a specific reconstruction algorithm allowing for reduction in acquisition times with no loss in image quality. …