Positron emission tomography as a diagnostic tool. A reassessment based on literature review.

Currently used clinical diagnostic imaging modalities, such as magnetic resonance imaging (MRI) and x-ray computed tomography (CT) provide predominantly anatomic information. CT images reflect x-ray attenuation distribution in the body, whereas MRI signals depend primarily on proton density and tissue relaxivity. In contrast to these predominantly anatomic modalities, positron emission tomography (PET) reflects tissue physiology and metabolism. Although PET has been used predominantly as a research tool, the clinical use of this technique for the detection, noninvasive characterization, and treatment planning of selected disease processes has been extensively studied in oncology, cardiology, and neurology. The author examined currently available literature to reassess the potential role of PET as a diagnostic tool in the following specific clinical situations: (1) the differentiation of radiation necrosis from tumor recurrence; (2) the characterization of the physiologic significance of coronary stenosis and the evaluation of the myocardial viability; and (3) the localization of the epileptogenic foci.