18-Fluorodeoxyglocose imaging with positron emission tomography and singlephoton emission computed tomography: Cardiac applications

The assessment of myocardial viability has become an important aspect of th e diagnostic and prognostic work-up of patients with ischemic cardiomyopath y. Although revascularization may be considered in patients with extensive viable myocardium, patients with predominantly scar tissue should be treate d medically or evaluated for heart transplantation. Among the many viabilit y tests, noninvasive assessment of cardiac glucose use (as a marker of viab le tissue) with F18-fluorodeoxyglucose (FDG) is considered the most accurat e technique to detect viable myocardium. Cardiac FDG uptake has traditional ly been imaged with positron emission tomography (PET). Clinical studies ha ve shown that FDG-PET can accurately identify patients with viable myocardi um that are likely to benefit from revascularization procedures, in terms o f improvement of left ventricular (LV) function, alleviation of heart failu re symptoms, and improvement of long-term prognosis. However, the restricte d availability of PET equipment cannot meet the increasing demand for viabi lity studies. As a consequence, much effort has been invested over the past years in the development of 511-keV collimators, enabling FDG imaging with single-photon emission computed tomography (SPECT). Because SPECT cameras are widely available, this approach may allow a more widespread use of FDG for the assessment of myocardial viability. Initial studies have directly c ompared FDG-SPECT with FDG-PET and consistently reported a good agreement f or the assessment of myocardial viability between these 2 techniques. Addit ional studies have shown that FDG-SPECT can also predict improvement of LV function and heart failure symptoms after revascularization. Finally, recen t developments, including coincidence imaging and attenuation correction, m ay further optimize cardiac FDG imaging (for the assessment of viability) w ithout PET systems. Copyright (C) 2000 by W.B. Saunders Company.