Statistical Considerations in Lung Imaging with ^99mTc Albumin Particles

Two patients were studied with serial lung imaging following the injection of increasing numbers of albumin microspheres to determine the number of particles required to give satisfactory lung images. Definite scan abnormalities were observed when less than 15,000 particles were injected. However, in view of the many imaging variables and the inability to inject all particles in the syringe, it is recommended that one administer a minimum of 60,000 albumin microspheres. This will avoid false positive scans resulting from an insufficient number of particles when using currently available instrumentation.