Myocardial perfusion scintigraphy



This method monitors the accumulation of radiopharmaceuticals in the tissue, which is higher when the monitored area is perfused better. We focus mainly on the left ventricular muscle. It is the most common cardiological examination in the field of nuclear medicine.

The examination can be performed at rest and during exercise, both physical and pharmacological (vasodilators, sympathomimetics). SPECT is used more often to monitor and evaluate the result, planar scintigraphy is also possible, although it has less spatial accuracy.

Indication
Patients with suspected acute coronary syndrome and chronic ischemic heart disease are most often indicated to be monitored for the extent of myocardial blood flow.

Myocardial perfusion scintigraphy plays an important role in the prognosis and further monitoring of myocardial status during and after treatment.

Radiopharmaceuticals
Radiopharmaceuticals with high affinity for myocardial structures are used.

99m Tc-MIBI (methoxyisobutylisonitrile) binds to mitochondria, of which there are many in the myocardium.

201 thallium - a cation, very similar to potassium, its first passage can be monitored, as well as (after 24 hours) the total distribution of potassium (or functional Na / K-ATPase) in the myocardium. The ischemic area shows slower uptake (slow wash-in) and retains the accumulated radiopharmaceutical (slow wash-out) for longer.

Implementation and output
After administration of the radiopharmaceutical, we monitor its accumulation in the heart. Gated scintigraphy can be used for this, which cooperates with the ECG, the recording is the same as for gated ventriculography (Radionuclide examinations of the heart). The ECG gated SPECT, which has a better explanatory value, can also be performed in the same way.

From the ECG gated SPECT we can obtain individual sections of the heart in three planes and 3D reconstruction. This output is excellent for monitoring the placement of a lesion in space. Polar maps compose a 3D image into a two-dimensional "floor plan" by the myocardium, as if we were looking at the heart from the apex. This output is sometimes called the bull's eye. Necrosis then manifests as a failure in a certain part of the circle. This image is usually supplemented by an indication of the course of the coronary arteries and thus finds out in which basin of which artery the ischemia occurred.

In cooperation with computer technology, it is possible to calculate the activity of the radiopharmaceutical in the blood and thus approximately determine the volume of blood flowing through the individual parts. It is also possible to objectively compare the results at rest and under load.

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