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The nuclear stress test exhibits a sensitivity of 81% and a specificity ranging from 85 to 95%. [22] To arrive at the patient's post test likelihood of disease, the interpretation of the stress test result necessitates the integration of the patient's pretest likelihood with the test's sensitivity and specificity.
As the gamma camera images are acquired, the patient's heart beat is used to 'gate' the acquisition. The final result is a series of images of the heart (usually sixteen), one at each stage of the cardiac cycle. [citation needed] Depending on the objectives of the test, the doctor may decide to perform either a resting or a stress MUGA.
Myocardial perfusion imaging or scanning (also referred to as MPI or MPS) is a nuclear medicine procedure that illustrates the function of the heart muscle (). [1]It evaluates many heart conditions, such as coronary artery disease (CAD), [2] hypertrophic cardiomyopathy and heart wall motion abnormalities.
Cardiac magnetic resonance imaging perfusion (cardiac MRI perfusion, CMRI perfusion), also known as stress CMR perfusion, [1] is a clinical magnetic resonance imaging test performed on patients with known or suspected coronary artery disease to determine if there are perfusion defects in the myocardium of the left ventricle that are caused by narrowing of one or more of the coronary arteries.
The resulting two sets of images are compared with each other to distinguish ischemic from infarcted areas of the myocardium. This imaging technique has a sensitivity of around 90%. [2] Resting images are useful only for detecting tissue damage, while stress images will also provide evidence of coronary artery (ischemia) disease. [3] [4]
The underlying principle is, under conditions of stress, diseased myocardium receives less blood flow than normal myocardium. MPI is one of several types of cardiac stress test. As a nuclear stress test, the average radiation exposure is 9.4 mSv, which when compared with a typical 2 view chest X-ray (.1 mSv) is equivalent to 94 Chest X-rays. [83]
A physician may recommend cardiac imaging to support a diagnosis of a heart condition. Medical specialty professional organizations discourage the use of routine cardiac imaging during pre-operative assessment for patients about to undergo low or mid-risk non-cardiac surgery because the procedure carries risks and is unlikely to result in the change of a patient's management. [1]
Coronary steal is also the mechanism in most drug-based cardiac stress tests; When a patient is incapable of doing physical activity they are given a vasodilator that produces a "cardiac steal syndrome" as a diagnostic procedure. The test result is positive if the patient's symptoms reappear or if ECG alterations are seen. [citation needed]