Introduction
Myocardial perfusion imaging, or MPI, is a diagnostic imaging test that displays blood flow through the heart. Myocardial perfusion imaging is a non-invasive test that helps us understand blood perfusion through the heart. This test is distinctive from other cardiovascular diagnostic tests because it shows the flow of blood within those structures of the heart that are next to impossible to angulate. Another name for the myocardial perfusion test is a nuclear stress test. The pumping of the heart and blood flow to the heart muscles can be clearly understood via this particular test.
Two techniques are used to conduct the test: single photon emission computed tomography or SPECT and positron emission tomography or PET. Myocardial perfusion imaging is beneficial for patients suffering from long-standing discomfort in the chest due to issues such as narrowed cardiac arteries or lack of blood flow. It should be noted that the blood vessels are not visible in this particular test, but the presence or absence of a blockage can be understood very well by the healthcare professional.
A heart that has undergone an episode of heart attack can also be visualized under myocardial perfusion imaging. The diagnosis made after the test generally aids in going ahead with coronary angiography. No abnormalities in the myocardial perfusion imaging declare the symptoms are not arising from the cardiovascular system.
What Are the Uses of Myocardial Perfusion Imaging?
Myocardial perfusion imaging explains the flow of blood through the cardiac muscles. In case there is a lack of flowing blood or an obstructive blood flow pattern during stress and exercise but no abnormality while at rest, it indicates the presence of a blockage or narrowing of the heart's arteries. If only a particular section of the heart shows a lack of blood flow, a specific area has undergone severe stress, such as a heart attack, and thus the muscles are scarred.
Mentioned below are some conditions that use myocardial perfusion imaging as a diagnostic measure to determine the underlying condition.
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Long-standing chest pain.
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Discomfort during breathing.
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Determiner for coronary angiography.
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Outlook of coronary stent surgery.
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To improve blood flow.
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The capacity of the heart to undergo physical activities.
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Helps to understand the bypass surgery prognosis.
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Diagnosis of coronary artery disease.
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Understand cardiovascular abnormalities.
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Evaluation of shortness of patient's breath.
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Justification for revascularization.
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Patients who are at risk of myocardial infarction.
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To detect an event of an ischemic heart attack.
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To understand the functioning of the walls of the heart.
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To diagnose the presence of a coronary aneurysm.
What Are the Possible Risks of Myocardial Perfusion Imaging?
The majority of radiological tests are safe for the general public. Myocardial perfusion imaging is considered safe if shot at a low X-ray dose. This is because low doses of X-rays do not lead to cancer and thus are safe. There is another school of thought that disagrees with the above notion. Bearing the same into consideration, myocardial perfusion imaging should not be suggested in the following patients.
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Pregnant females.
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Low chances of myocardial infarction.
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Nursing mothers.
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Seldom a few episodes of chest pain.
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No family history of cardiovascular disease.
What Is Done Before a Myocardial Perfusion Imaging?
The patient is expected to inform their healthcare provider of any drug allergies, medical history, or family history of cardiovascular disease. Additionally, if the patient is on medications or herbal supplements, as well as any food allergies, they must give a detailed account of the same. Certain types of food are suggested to stay away from a day before the imaging. These include caffeinated beverages, chocolates, and heavy food. The imaging test is postponed to another day if caffeinated drinks are consumed.
What Is Done During a Myocardial Perfusion Imaging?
Myocardial perfusion imaging is a scheduled test and is not a routine procedure. Rarely it is done under extreme circumstances of emergency.
Mentioned below are the steps done during a myocardial perfusion imaging procedure.
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Tiny electrodes made up of metal disks are placed on the patient's chest, legs as well as arms of the patient.
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The electrode discs are attached to a machine that tracks electrocardiograms.
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The ECG or electrocardiogram directs the camera whenever an image is required to be clicked.
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A blood pressure cuff around the arm monitors the patient's blood pressure.
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An intravenous line is inserted into the arm.
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The patient is asked to exercise or is placed on a bicycle.
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A chemical, pharmacological test is an alternative for patients who cannot do physical exercise.
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A pharmacological stress test is also called a chemical exercise test because the intravenous line is linked to a pouch that contains medications to increase blood flow to the heart parallel to the phenomenon during exercise.
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At the peak level of physical activity, a tiny amount of tracer is passed through the intravenous line, a radioactive material.
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A gamma imaging camera captures images of the heart while the patient is flat on the table for around half an hour.
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Thin slices over all the angles of the heart are captured.
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The patient must not move during gamma imaging to receive accurate results.
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The entire test is completed within four hours.
Conclusion
Myocardial perfusion imaging, or MPI, is a diagnostic measure to understand several aspects of the functioning of the cardiovascular system, especially the heart. Single photon emission computed tomography or SPECT and positron emission tomography or PET are the two kinds of myocardial perfusion imaging. The test is not done under routine cardiovascular checkups. Instead, it is suggested only if there is a lack of understanding of the heart's deeper structures that are not easily visible even after several other diagnostic tests. Myocardial perfusion imaging is done under low doses and thus is safe, but only for a particular group of individuals.
