Standard LV performance may be assessed in two ways: A first-pass bolus technique may be used that quantitates individual end-systolic and end-diastolic relative volumes as the bolus passes through the right heart into the lungs and through the LV. Regions of interest are manually determined around the LV at end-diastole and end-systole to provide the counts necessary for calculation of LVEF. (end-diastole volume minus end-systolic volume divided by end-diastolic volume).
Alternatively, gated equilibrium blood pool imaging (multiple gated acquisition, MUGA) of the left and right ventricles may be performed to assess myocardial performance. An aliquot of the patient's red blood cells is labeled with sodium pertechnetate and reinjected for subsequent imaging in three static-image cardiac positions.
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The camera is triggered at the onset of each R-wave for each cardiac cycle; the R-R interval is divided into 16 frames and is compiled into summed images. These average data in image format are subsequently processed and displayed as a continuous cinematic loop to stimulate cardiac motion during the cardiac cycle. From this display, a region of interest is identified around LV end-diastolic and end-systolic volumes again to calculate LVEF.
Also from the display, regional myocardial wall motion may be determined from each LV segment.