Combined static-dynamic single-dose cardiac SPECT for quantitative myocardial perfusion imaging

Objectives: SPECT myocardial perfusion imaging (MPI) is typically performed with static imaging protocols. Although widely used, it has several limitations and challenges. Dynamic imaging, on the other hand, permits longitudinal assessment of radiotracer distribution, and yields additional information on the physiologic significance of a coronary lesion by providing myocardial blood flow (MBF) and coronary flow reserve (CFR). The main goal of this study was to demonstrate the viability of a single-dose one-day dynamic-static SPECT MPI protocol using a commonly available gamma camera (GE Infinia Hawkeye-4) with ^99mTc-tetrofosmin.

Methods: Fifteen patients (10 males and 5 females) with suspected coronary artery disease (CAD) were enrolled in this study. Eight patients also underwent selective coronary angiography (SCA). A low/high-dose ^99mTc-tetrofosmin rest (10 mCi)/regadenoson-induced pharmacologic stress (25 mCi) protocol was implemented in a single day visit with dynamic followed by static acquisitions. The extent and severity of perfusion defects in each myocardial region was graded visually on a scale of 0 to 4 (0 = normal; 4 = absence of uptake) on both image sets. Data acquired dynamically were also used to estimate the MBF and CFR for three major coronary arteries.

Results: Among 15 dynamic SPECT studies, 9 showed concordance and 6 were discordant with the static SPECT images. Compared to SCA, 6 dynamic SPECT studies agreed and 2 differed while 5 clinical SPECT agreed with SCA and 3 differed. The 6 dynamic SPECT CFR measurements also showed concordance with the SCA.

Conclusion: This preliminary study shows the potential value and feasibility of combined static-dynamic SPECT in a clinical setting. Dynamic SPECT provides additional quantitation of CFR, which improves the accuracy of detection of CAD. Research Support: The study was supported in part by the National Institutes of Health.