Positron computed tomography and its applications in the young.

Positron computed tomography is a new method for the external quantification of regional myocardial blood flow, substrate fluxes and biochemical reaction rates. It takes advantage of positron emitting tracers, metabolically active tracers, tracer kinetic principles and the quantitative imaging capabilities of the tomograph. To date, the technique has been used primarily for the study of ischemic heart disease and cardiomyopathies in adults. However, initial studies in infants and adolescents with regional cardiomyopathies provide evidence for its potential value in detecting disease at the biochemical level or at a stage that antedates clinical manifestations and cardiac dysfunction. Positron computed tomography is likely to contribute to our understanding of metabolic abnormalities associated with cyanotic or congenital heart disease and of the heart's maturation, and may become useful for optimal timing of corrective surgery. It allows the study of intrinsic myocardial disease in children, clarification of disease mechanisms and diagnosis of congenital metabolic disorders. It also might become useful for detecting disease when it is still confined to biochemical derangements and permit institution of therapy that may halt progression or even reversal of disease before irreversible morphologic changes develop. The high cost of equipment purchase and operation has precluded widespread use, but new technologic developments may make it possible to perform these studies at a cost comparable with that of other noninvasive procedures. Positron computed tomography may then become available as a routine diagnostic tool for studying pediatric cardiac disorders.