Are SPECT measurements of myocardial blood flow and flow reserve ready for clinical use?

Abstract

SPECT myocardial perfusion imaging (MPI) well-documented diagnostic accuracy for detecting coronary artery disease (CAD) has promoted the widespread clinical use of this modality. Nevertheless, SPECT MPI’s success has been attained using the basic SPECT camera design which is over 50 years old [1], using the basic filtered backprojection reconstruction algorithm which is even older, dating to over 90 years ago [2], and using Tc-99m based perfusion agents with limited extraction fractions [3]. Moreover, although SPECT MPI is inherently a digital, quantitative technique, our clinical approach to quantify hypoperfusion has depended on a database approach where a patient’s left ventricular perfusion pattern is statistically compared to an expected normal perfusion pattern generated from patients with low likelihood of CAD [4–6]. In spite of the success of SPECT MPI using these established conventional approaches, recent innovations are poised to bring SPECT MPI to the next level. In a recent article in EJNMMI, Hsu et al. [7] report on the use of dynamic SPECT with a SPECT/CT camera, to measure absolute myocardial blood flow (MBF) and myocardial blood flow reserve (MBFR) in patients. The authors conclude that their flow quantitation method is a clinically effective approach to enhance CAD detection. Thus it is pertinent to ask: Are SPECT measurements of myocardial blood flow and flow reserve ready for clinical use?