Because the heart is effectively imaged more than once (described above), cardiac CT<unk>  can result in a relatively high radiation exposure (around 12 millisievert), although newer acquisition protocols, have recently been developed which drastically reduce this exposure to around 1 mSv (cfr. Pavone, Fioranelli, Dowe: Computed Tomography or<unk>  Arteries, Springer 2009). By comparison, a chest X-ray carries a dose of approximately 0.02-0.2 mSv and natural background radiation exposure is around 2.3 mSv/year. Thus, each cardiac CT scan carried out with current protocols (dose approximately 1 mSv) is equivalent to approximately 5-50 chest X-rays or less than 1 year of background radiation. Methods are available to decrease this exposure, however, such as prospectively decreasing radiation output based on the concurrently acquired ECG (i.e. tube current modulation.) This can result in a significant decrease in radiation exposure, at the risk of compromising image quality if there is any arrhythmia during the acquisition. The significance of the low radiation doses used in diagnostic imaging is unknown, although the possibility of increasing cancer incidence across a population is of significant concern. This potential risk must be weighed against the competing risk of not diagnosing a significant health problem in a particular individual, such as<unk>  artery disease. Contraindications Pregnancy is considered a relative contraindication, similarly to many forms of medical imaging in pregnancy. The potential harms to a fetus include the application of X-rays in addition to radiocontrast. Since an iodine-containing contrast agent is used, severe contrast agent allergy, uncontrolled hyperthyroidism or renal function impairment are also relative contraindications. Cardiac arrhythmias,<unk>  artery stents and tachycardia may result in a reduced image quality.
Coronary CT angiography
Coronary CT calcium scan
Cardiac magnetic resonance imaging perfusion
Impedance cardiography
Cardiac magnetic resonance imaging
Intracoronary optical coherence tomography
Cardiac ventriculography
Cardiac electrophysiology