Myocardial perfusion scintigraphy
What is it?
The examination is based on the injection into a vein of a small amount of radioactive material and the detection, using special equipment (gamma camera), of the distribution of the injected substance in the heart muscle in resting conditions and after a stimulus (physical or pharmacological stress), which determines an increase in flow through the coronary arteries.
If there are differences between the distribution of the radiopharmaceutical in a resting condition and after stimulus, the presence of coronary artery disease can be assumed. Since 2011 a new gamma chamber dedicated to cardiac studies is available (MN 530 - General Electric), which allows the execution of tomographic studies with shorter duration period than the others and to administer a lower dose of radiopharmaceutical to the patient, thus significantly reducing the radiation exposure.
The studies are performed in a single-day acquisition mode, i.e. by conducting the study after physical or pharmacological stress and in rest within the same day.
However, in case of particular needs, it is possible to carry out the examination in two different days.
When is this exam indicated?
Myocardial perfusion scintigraphy allows non-invasive assessment of cardiac perfusion and pump function of the heart.
- Coronary heart disease
How is it performed?
The examination is performed by injecting the tracers Tc-99m MIBI or Tc-99m Tetrafosmin in resting condition and after a provocative test, followed by the acquisition of scintigraphic images, lasting about 10 minutes.
The provocative test consists of a physical effort obtained with a treadmill that progressively increases the speed and the slope. The effort will be continued until the achievement of specific electrocardiographic and/or clinical parameters, which are constantly monitored during the test.
In case of patients unable to perform an adequate physical effort, with walking problems, pacemaker carriers or with left bundle-branch block, it is possible to perform the pharmacological provocative test by administration of dipyridamole.
The stay in the department for the examination in a single day is about 3-4 hours; if the examination must be performed in two different days (due to inadequate preparation of the patient) the time spent in the department is about 90'-120'. The preparation of the examination requires a fast of about 6 hours, refusal of tea, coffee, coca cola and chocolate within 24 hours prior to the examination.
The therapy must be taken regularly, according to the usual schedule, including the morning of the examination, with the exception of some drugs that modify the coronary flow and that can be suspended by the cardiologist.
Contraindications
The test is contraindicated during pregnancy or lactation. Exercise test on treadmill: recent myocardial infarction (<48h), unstable angina, heart failure in the decompensation phase, hemodynamically unstable arrhythmia, acute myocarditis or pericarditis, severe or symptomatic aortic stenosis, respiratory failure, grade II atrioventricular block, severe pulmonary hypertension, embolism or recent pulmonary infarction. Pharmacological provocative test: presence of bronchial asthma, severe bronchopneumopathy, hypertrophic obstructive cardiomyopathy, severe or symptomatic aortic stenosis, severe hypotension, presence of critical carotid stenosis, and for patients with recent episode of cerebral ischemia.
Where do we treat it?
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