The judgement of the eye

Excerpt

The point-counterpoint of Saab et al, and Reynes et al2,3 is very well done and reminiscent of the Mirror of Erised of the Harry Potter series in which one sees their desire while gazing into it. Both make compelling arguments on the impact of caffeine ingestion on the accuracy of SPECT myocardial perfusion imaging. Both quote from the same studies, yet see opposite but credible conclusions. Clearly, there is a literature supporting an inhibitory action of caffeine-containing products on coronary vasodilation mediated by adenosine A2 receptors but the timing, dosage, vasodilator agent, and specific genetic predisposition to caffeine variability clouds the looking glass. The first description of caffeine impact on dipyridamole-mediated vasodilation was in 1989.4 Twenty-five years later, the impact of the issue is still uncertain. Why are we not further along? This piece will outline some concepts that have contributed to the confusion. These are within the categories of imaging algorithms, image displays, physics, tracer kinetics, and statistics. …