Studies of left ventricular volume estimation from gated blood pool scan with the use of regression equations

The authors carried out experimental and clinical studies of left ventricular volume measurement using equilibrium-gated blood pool scan. Using phantoms, we experimentally obtained a regression equation between radioisotope levels and camera counts. From this equation, we deduced a regression equation between camera counts and volumes, which was then used for calculation of left ventricular volumes using count technique. In an experiment using phantom with various volumes, we obtained a favorable result that the average absolute error between the true and measured volumes was as small as 6.8%. In 11 patients, we calculated the left ventricular volume and ejection fraction employing the regression equation and compared the calculated values with the values obtained by cinemascopy. This comparison disclosed an excellent correlation (r = 0.955 for end-diastolic volume, 0.997 for end-systolic volume and 0.853 for ejection fraction). Mean absolute error was 16.2% for end-diastolic volume and 16.0% for end-systolic volume. These results indicate that this technique is clinically applicable.