<Li> Post intervention revascularization (coronary artery bypass graft, angioplasty) evaluation of heart . </Li> <Li> Evaluation of shortness of breath of a possible cardiac origin . </Li> <P> From 1993 to 2001, myocardial perfusion scans in the US increased> 6% / y with "no justification". Myocardial perfusion imaging scans are "powerful predictors of future clinical events", and in theory may identify patients for whom aggressive therapies should improve outcome . But this is "only a hypothesis, not a proof". However, several trials have indicated the high sensitivity (90%) of the test, regardless of tracer, outweighing any potential detrimental effect of the ionising radiation . In the UK, NICE guidance recommends myocardial perfusion scans following myocardial infarction or reperfusion interventions . The power of prognosis from a myocardial perfusion scan is excellent and has been well tested, and this is "perhaps the area of nuclear cardiology where the evidence is most strong". </P> <P> Many radionuclides used for myocardial perfusion imaging, including rubidium - 82, technetium - 99m and thallium - 201 have similar typical effective doses (15 - 35 mSv). The positron emission tomography (PET) tracer ammonia - 13, though less widely available, may offer significantly reduced doses (2 mSv). Stress - only protocols may also prove to be effective at reducing costs and patient exposure . </P>

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