Mathematics regarding acquisition of cardiac output (Q) is well served by both of these methods as well as other inexpensive models supporting ejection fraction as a product of the heart/myocardium in systole.

[1] The MUGA scan was first introduced in the early 1970s and quickly became accepted as the preferred technique for measurement of left ventricular ejection fraction (LVEF) with a high degree of accuracy.

Several early studies demonstrated an excellent correlation of MUGA-derived LVEF with values obtained by cardiac catheterization contrast ventriculography.

[3] MUGA is typically ordered for the following patients:[citation needed] Radionuclide ventriculography gives a much more precise measurement of left ventricular ejection fraction (LVEF) than a transthoracic echocardiogram (TTE).

Transthoracic echocardiogram is highly operator dependant, therefore radionuclide ventriculography is a more reproducible measurement of LVEF.

Its primary use today is in monitoring cardiac function in patients receiving certain chemotherapeutic agents (anthracyclines: doxorubicin or daunorubicin) which are cardiotoxic.

A subsequent intravenous injection of the radioactive substance, technetium-99m-pertechnetate, labels the red blood cells in vivo.

In both cases, the stannous chloride reduces the technetium ion and prevents it from leaking out of the red blood cells during the procedure.

[6][7] The in vivo technique is more convenient for the majority of patients since it is less time-consuming and less costly and more than 80 percent of the injected radionuclide usually binds to red blood cells with this approach.

Red blood cell binding of the radioactive tracer is generally more efficient than in vitro labeling, and it is preferred in patients with indwelling intravenous catheters to decrease the adherence of Tc-99m to the catheter wall and increase the efficiency of blood pool labeling.

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.

[citation needed] The resulting images show that the volumetrically derived blood pools in the chambers of the heart and timed images may be computationally interpreted to calculate the ejection fraction and injection fraction of the heart.

This nuclear medicine scan yields an accurate, inexpensive and easily reproducible means of measuring and monitoring the ejection and injection fractions of the ventricles, which are one of many of the important clinical metrics in assessing global heart performance.

[citation needed] It exposes patients to less radiation than do comparable chest x-ray studies.

However, the radioactive material is retained in the patient for several days after the test, during which sophisticated radiation alarms may be triggered, such as in airports.

[3] Radionuclide ventriculography has largely been replaced by echocardiography, which is less expensive, and does not require radiation exposure.

[citation needed] In normal subjects, the left ventricular ejection fraction (LVEF) should be about 50%[9](range, 50-80%).

For normal subjects, peak filling rates should be between 2.4 and 3.6 end diastolic volume (EDV) per second, and the time to peak filling rate should be 135-212 ms. [citation needed] An uneven distribution of technetium in the heart indicates that the patient has coronary artery disease, a cardiomyopathy, or blood shunting within the heart.

Abnormalities in a resting MUGA usually indicate a heart attack, while those that occur during exercise usually indicate ischemia.

In a stress MUGA, patients with coronary artery disease may exhibit a decrease in ejection fraction.

[citation needed] The Massardo method[10] is one of a number of approaches for estimating the volume of the ventricles and thus ultimately the ejection fraction.

The pixel values in such an image represent the number of counts (nuclear decays) detected from within that region in a given time interval.

The Massardo method enables a 3D volume to be estimated from such a 2D image of decay counts via:[citation needed]

The Massardo method relies on two assumptions: (i) the ventricle is spherical and (ii) the radioactivity is homogeneously distributed.

[citation needed] The Siemens Intevo SPECT scanners employ the Massardo method in their MUGA scans.

Assuming that the activity is homogeneously distributed, the total count is proportional to the volume.

The maximum pixel count is thus proportional to the length of the longest axis perpendicular to the collimator,

The Massardo method now makes the simplification that the ventricle is spherical in shape, giving