Routine clinical positron emission tomography for diagnostic cardiac imaging--a review

Positron emission tomography, advanced through technical developments, has now evolved into a routinely applicable method for clinical investigation. The rubidium-82 generator, without the need for a cyclotron, provides a source of positron radionuclide which enables delineation of cardiac structures. Three characteristics of positron cameras are particularly essential for cardiac imaging: overlapping image planes to provide uniform sampling between detector rings, a high sensitivity to acquire high count rates, and clinically oriented software that is user-friendly. The most useful indications for positron emission tomography include assessment of myocardial perfusion (for which the diagnosis of coronary artery disease can be established with a sensitivity of 95 to 98% and specificity of 99 to 100%), assessment of the physiologic severity of coronary artery stenoses and the influence of interventions such as PTCA or thrombolysis, myocardial infarct imaging, assessment of viability of reversibly injured or ischemic cells, assessment of regional or global left ventricular function and analysis of collateral flow. The radiation burden to the patient is generally lower than that of standard cardiac nuclear tracer such as Tl-201. Thus, cardiac positron emission tomography provides information not previously available for better diagnosis and management of cardiac disease. This technique may obviate the need for other routinely-applied nuclear imaging techniques. Should the services of a cyclotron be available, the method offers, in addition, the possibility to perform complex studies of myocardial metabolism.