Combined assessment of myocardial perfusion and left ventricular function by nuclear cardiology: The value of high-efficiency SPECT

Abstract

The introduction of ECG gating to myocardial perfusion SPECT imaging (MPI) more than 20 years ago provided the opportunity for the combined assessment of myocardial perfusion and left ventricular (LV) function with a single radiotracer injection.1 Software for automatic quantification of left ventricular volume and ejection fraction (EF) was developed, and ECGgated SPECT became a widespread, routine part of MPI acquisition and interpretation.2 Although simultaneously acquired, myocardial perfusion images represent coronary flow distribution at peak stress, whereas gated images demonstrate LV function at the time of acquisition. It has soon been realized that stress-induced ischemia was frequently associated with lower poststress EF than resting EF.3 This post-stress stunning phenomenon of global LV function was further supported by the identification of post-stress regional wall motion abnormality, indicating severe obstructive coronary artery disease (CAD). Post-stress stunning is transient in nature, and recovers often over 60 minutes after stress cessation.5 Its early detection using a conventional Anger-camera is limited by several technologically inherent pitfalls: First, the need to wait for at least 15 minutes, and sometimes up to 60 minutes following a radiotracer injection before initiating image acquisition because of hepatic uptake; 6,7 second, acquisition time itself is very long, frequently more than ten minutes, allowing partial recovery of the LV function during the acquisition itself. Thus, acquiring images at peak stress or very early post-stress using a conventional camera is unfeasible. Nevertheless, previous studies demonstrated the added diagnostic value of conventional post-stress gated SPECT in the detection of severe coronary artery disease, and the incremental prognostic value of post-stress EF and end-systolic volume over the extent, and severity of perfusion defects in predicting future cardiac events. 8 In this issue of the journal, Brodov et al from Cedars-Sinai Medical Center and Oregon Heart and Vascular Institute demonstrated for the first time the feasibility to obtain early gated stress acquisitions of acceptable quality using a high-efficiency SPECT camera, and to detect early stunning and its recovery over time. They evaluated 50 patients who underwent regadenoson same-day rest/stress MPI, using the D-SPECT CZT camera (Spectrum Dynamics, Caesarea, Israel). Following regadenoson and Tc-99m injection, sequential 2-minute acquisitions were performed starting at 1, 5, 9, 13, and 17 minutes, and a last 4-minute acquisition starting 21 minutes following injection. The first acquisition, starting one minute after injection was of unacceptable quality, and discarded from the analysis. EF reserve was calculated as the absolute difference between stress and rest EF for each of the sequential post-stress acquisitions. Significant ischemia was defined as ischemic total perfusion deficit C5%, and a 50-patient group was divided into two subgroups based on this cutoff value. The results demo...

Cadmium-zinc-telluride myocardial perfusion imaging: The dream of a single test gets nearer

“…7 The recent introduction of the cadmium-zinc-telluride (CZT) cameras for SPECT has purportedly revolutionized MPI, thanks to their superior spatial and energy resolution. 8,9 Given their groundbreaking technical features and the differences between the two available but competing suites (D-SPECT, Spectrum Dynamics, Palo Alto, CA, USA; Discovery NM 530c or Discovery NM/CT 570c with Alcyone technology, GE Healthcare, Haifa, Israel), there are, however, ongoing developments and refinements in the application of this imaging technology to current cardiovascular practice. [10][11][12] Accordingly, the scholarly literature on CZT MPI is continuing to expand momentously, as demonstrated by the work by Jameria and colleagues published in this issue of the Journal.…”

“…In light of the work of Jameria and colleagues, and the total body of evidence on this topic, [8][9][10][11][12] it is important to highlight the current and future prospects of CZT technology for MPI. First, it is paramount to recognize that the two available embodiments of this technology (Alcyone and D-SPECT) might not be identical in performance, despite aggregate analyses suggesting the contrary.…”