Recent advances in gamma camera technology are providing opportunities for novel high-speed myocardial perfusion imaging (HS-MPI) protocols. We aimed to develop and evaluate a stress thallium-201 (Tl-201) and rest Tc-99m sestamibi or tetrofosmin imaging protocol that could reduce imaging time and radiation burden.
Methods: We studied 410 consecutive patients undergoing exercise or pharmacologic low-dose stress Tl-201 HS-MPI (4 min/acquisition) in the semi-upright and supine positions (D-SPECT, Spectrum-Dynamics) followed by rest Tc-99m sestamibi (n= 139) or tetrofosmin (n= 271) with immediate post-injection rest imaging. Of 330 patients with no known coronary artery disease (CAD), 29 patients also underwent invasive coronary angiography (ICA) or coronary computed tomography angiography (CCTA) within a three month period and 36 had a < 5% pre-test likelihood of CAD (LLk). Despite low injected doses [Tl-201 (2.2± 0.3 mCi) and Tc-99m sestamibi or tetrofosmin (8.9± 2.4 mCi), the 3 acquisition MPI protocol (2 stress/1 rest) was accomplished < 20 minutes. The quality of stress and resting image was good to excellent in >96% of cases; importantly, no or minor extracardiac activity was seen on 99% of stress and 93% of rest images. HS-MPI was nondiagnostic or uninterpretable in only 2/410 patients. In the 29 patients with CCTA or ICA, the sensitivity and specificity for the detection of ≥70% stenosis were 73% and 89%, respectively, and in 15 patients with ICA, the sensitivity was 89%. The normalcy rate in the LLk group was 100%. A fast stress Tl-201/rest Tc-99m HS-MPI protocol offers promise as a time-efficient, low radiation dose method, in which the superior qualities of Tl-201 for stress imaging and of Tc-99m agents for rest imaging can be utilized.
High-Speed Myocardial Perfusion Imaging: Dawn of a New Era in Nuclear Cardiology?
