 A continuous intravenous infusion is administered for a few minutes until there are hemodynamic signs of vasodilatation, then a bolus of contrast medium is administered while acquiring saturation recovery images of the heart with a high temporal resolution readout.A positive result is evident from an inducible myocardial perfusion defect.Cost and availability mean that its use is often confined to patients with intermediate pre-test probability, but it has been shown to reduce unnecessary angiography compared with guidelines-directed care.