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Is 31P-NMR spectroscopic imaging a viable approach to assess myocardial viability?

Thallium-201 imaging in its various forms (initial followed by 2- to 4-hour or 24-hour delayed imaging, initial followed by imaging after reinjection, or a “hybrid” approach using 201Tl initially and 99mTc-sestamibi later) is a reasonable clinical approach for assessment of myocardial perfusion and viability.1 2 3 4 However, other approaches that examine change in regional myocardial function during dobutamine infusion and evaluate metabolic myocardial integrity with exogenous administration of radioactive tracers also have been reported.5 6 7 Accordingly, one may justifiably wonder how nuclear magnetic resonance (NMR) spectroscopic imaging, another expensive, high-tech approach, might ever be used as a clinical tool for assessing myocardial viability, especially in this era of healthcare reform, managed care, and capitation. 

Yabe et al8 report a new clinical approach for evaluating myocardial viability. The method uses 31P-NMR spectroscopic imaging (SI) to quantify the high-energy phosphates ATP and phosphocreatine (PCr). The use of ATP concentration as a standard for assessing myocardial viability is not new.9 What is new is the ability to estimate ATP and PCr concentrations clinically and noninvasively in asynergic segments of myocardium. 

Wall motion abnormalities associated with ischemic heart disease may be related to myocardial scar in patients with previous myocardial infarction, an irreversible situation, or to transient ischemic dysfunction (“stunning”)10 or persistent ischemic dysfunction (“hibernation”).11 Reversible or irreversible dysfunction can suggest the appropriate therapeutic strategy. With viable but dysfunctional myocardium, bypass graft surgery or catheterization laboratory intervention can lead to improved function and symptomatic state of the patient—or …