Cardiac chamber imaging: a comparison of red blood cells labeled with Tc-99m in vitro and in vivo.

A detailed comparison was performed between the quality of cardiac images obtained using red blood cells labeled in vitro and in vivo. Both methods gave cardiac images of high quality. The in vitro method resulted in subjectively superior images, better intravascular retention of injected radioactivity, and a higher left-ventricle-to-background count ratio (p less than 0.05). The differences in image quality and left-ventricular blood-pool activity were not great, however, and the slight advantage of the in vitro method was offset by a somewhat more complicated preparative procedure. We believe that both agents are suitable for radionuclide imaging of the cardiac chambers.