Mean Pulmonary Transit Time in First-Pass Studies

Abstract

We studied the measurement reproducibility of mean pulmonary transit time in first-pass radionuclide angiography. Two bolus injections of ^99mTc HDP were administered into each human subject approximately five minutes apart. Patients did not move between studies. The same regions of interest were used in both studies. Transit time measurement of the ^99mTc from the right ventricle to the left ventricle was first approximated by the time difference between the maxima of the time-activity curves and was then computed by fitting the time-activity curves to exponential functions. Both methods have comparable reproducibilities. Better precision was obtained by using the ejection fraction and cardiac cycle to monitor patient condition stability. Measurement of transit time was reproducible to an average of 0.40 ± 0.35 sec.