[Risk-benefit balance in cardiovascular imaging: the radiation issue]

Every year 5 billion diagnostic imaging procedures are performed worldwide, and about 1 out of 2 tests are cardiovascular examinations. According to recent estimates, 30% to 50% of all examinations are partially or totally inappropriate. This represents a potential damage in patients undergoing imaging tests (who take the acute risks of a stress test procedure and/or a contrast study without a commensurable benefit), an exorbitant cost for the society, and an excessive delay in the waiting lists for other patients needing the examination. In case of ionizing radiation, the reduction of useless imaging tests would improve the quality of care also through abatement of the long-term risks related to the dose employed. The radiation dose equivalent of common cardiological imaging examinations corresponds to about 500, 750 and 1000 chest X-rays for stress sestamibi testing, multislice cardiac computed tomography and coronary stenting, respectively. Although direct evaluation of the incidence of cancer in patients submitted to these procedures is not available, according to the latest 2006 Biological Effects of Ionizing Radiation Committee VII the estimated risk of cancer is about 1 in 750 for a computed tomography scan - higher in women (1/500), lower in the elderly (1/1500), and the highest in children (1/100 in female children aged <1 year). Such a risk is probably not acceptable when a diagnostic procedure is inappropriately applied for mass screening (when the risk side of the risk-benefit balance is not considered) or when similar information can be obtained by other means. By contrast, it is fully acceptable in appropriately selected groups as a filter to more invasive, risky and costly procedures.