Technetium‐99m‐sestamibi Redistribution after Exercise Stress Test Identified by a Novel Cardiac Gamma Camera: Two Case Reports

Abstract

Single photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) employing technetium-99m (Tc-99m)-based imaging tracers is the mainstay of nuclear cardiology for the detection of myocardial ischemia. Current guidelines for same day rest/stress Tc-99m-sestamibi SPECT MPI recommend image acquisition 15-60 minutes after the stress testing. A novel sensitive SPECT imaging technique, D-SPECT, allows fast acquisition of images and captures rapid changes in radiotracer distribution. Here we report 2 cases of SPECT MPI in patients with angiographically confirmed coronary artery disease (CAD) where Tc-99m-sestamibi exhibited marked redistribution between early (6-8 min) and late (60-70 min) post-stress imaging leading to an underestimation of the extent and severity of ischemia on late images. These observations suggest that early imaging maybe more sensitive for CAD detection. Fast SPECT imaging techniques, such as D-SPECT, will facilitate similar studies in the future as they will allow fast image acquisition at several time points after the stress test. BackgroundSingle photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) employing technetium99m (Tc-99m)-based imaging tracers is the mainstay of current nuclear cardiology practice providing both high sensitivity and specificity for the detection of myocardial ischemia. 1 Tc-99m-sestamibi injected at rest and peak stress is trapped within viable cardiomyocytes and its distribution observed with an Anger scintillation camera 15-60 minutes after tracer injection has been assumed to reflect the status of regional myocardial perfusion (MP) at the time of radionuclide injection. Here we report 2 cases of SPECT MPI in patients with angiographically confirmed coronary artery disease (CAD) where Tc-99m-sestamibi exhibited marked redistribution between early (6-8 min) and late (60-70 min) post-stress imaging, suggesting that early imaging may be more sensitive for CAD detection.

Fleming-Harrington Redistribution Wash-in Washout (FHRWW): The Platinum Standard for Nuclear Cardiology

“…Despite the report by DuPont (Crane 1993) and multiple other research and clinical (Everett 1977, Fleming 1992b, 2003e, Aodah 2007, Fallahi 2008) studies discussed above and below, which have clearly established that these isotopes redistribute and do not "stick", most clinicians have continued to ignore Blumgart's teaching of performing sequential evaluations under same state conditions and have subsequently limited their investigation of coronary artery disease to single post-stress imaging despite the teaching of nuclear imaging which notes that "a better indicator of organ function is the change in the activity in a particular organ with time." Newer clinical observations and publications (Sheikine 2010) have since been made confirming our earlier observations from 2000-2001. Inconsistencies in analysis of cardiac imaging have led some researchers (Fleming 2002b, Toriyama 2005, Oregon 2008) to recommend that these clinical studies be standardized quantitatively; something this study has accomplished. In medical school we were taught that there were two ways to understand the results of a test.…”

“…Clearly, these 2001 images show differences in isotope distribution between the 5 and 60-minute images. Similar findings have now been reported by others, including researchers at UCLA and Harvard Universities (Sheikine 2010).…”

“…These rather crude early findings (Figure 5) clearly demonstrated that individuals with ischemic heart disease revealed different distribution patterns of Sestamibi within cardiac tissue at 5 and 60 minutes post stress, proving that Sestamibi in fact "redistributes" within the heart and confirmed the information reported by others as noted above and as we will see in the remainder of this chapter, it has been confirmed by others world wide as well as recent work out of both UCLA and Harvard (Sheikine 2010). We have also demonstrated (Fleming 2009) that technetium-99m tetrofosmin (trade name Myoview) similarly redistributes.…”

“…As we continue to expand the number of individuals being studied with this method, it is clear that specific regional information can be determined from the parabolic equations used here and graphically displayed in Figure 32. The utilization of this knowledge will allow us to better determine which patients will benefit most from coronary angiography and has now been confirmed "qualitatively" by investigators at UCLA and Harvard Universities (Sheikine 2010). With the advent of nuclear cameras capable of faster image acquisition, we will undoubtedly be able to compare washout of the more rapidly redistributing technetium-99m compounds such as Teboroxime (Fleming 1990a-c, 1991a, 1992b, Goldstein 1991.…”

Dedicated cardiac cameras: a new option for nuclear myocardial perfusion imaging

“…The very fast acquisition capability of D-SPECT was employed by Sheikine et al [16] to study rapid changes in radiotracer distribution. They have recently described two cases of patients with angiographically proved CAD, in whom 99m Tc-sestamibi showed a notable redistribution between early (6-8 min) and late (60-70 min) post-stress imaging.…”