A Comparative Study, by Objective Quantization Using Microdensitometry, between Cardiac Pool Images Obtained Using Red Blood Cells Labeled in vivo with ^99mTc and Using ^99mTc-human Serum Albumin

Abstract

A detailed comparison was performed subjectively and objectively between the quality of cardiac pool images obtained using red blood cells lebeled in vivo with ^99mTc and ^99mTc-human serum albumin. Both methods gave cardiac pool images of high quality. In order to compare the images between both methods, the microdensitometry was performed in both images of the same patients along the line drawn through the center of the left ventricular image and the septal image. Measuring the highest density of left ventricle as C_L and that of septum as C_s, the index I (I_I) was obtained as (C_L-C_s) and the index II (I_I) was calculated as (C_L-C_s) / (C_L +C_s) . The objective comparison was performed by these indices. The method using red blood cells labeled in vivo with ^99mTc resulted in subjectively superior images and a higher left ventricle-to-septum density ratio in cases of control groups, myocardial infarction and aortic valvular disease. But in cases of mitral valvular disease and arrhythmia the in vivo method resulted in inferior or almost equal to the method obtained using ^99mTc-HSA. The quantitative indices used in this study can be thought to represent the contrast between the left ventricular image and the septal image. A better contrast may be obtained in a better image and may contribute more to the clinical diagnosis. From the point of clinical contribution, both agents are suitable for radionuclide imaging of the cardiac chambers. And the adequate combination of both method may be useful for clinical diagnosis.