Circulation, Vol 65, 311-322, Copyright © 1982 by American Heart Association
Factors that affect the reproducibility of measurements of left ventricular function from first-pass radionuclide ventriculograms
DS Dymond, A Elliott, D Stone, G Hendrix and R Spurrell
To examine which factors affect the reproducibility of ejection fraction
(EF), pulmonary transit time (PTT) and segmental wall motion assessed from
first-pass radionuclide angiograms (FPRA), 32 patients who had FPRA were
randomized for site of injection of isotope (right or left arm) and
projection (right or left anterior oblique [RAO or LAO]). The quality of
injected bolus was measured from the full width at half maximum (FWHM) of
the bolus time-activity curve in the superior vena cava. All patients had
two sequential studies on each of two consecutive days, and each study was
analyzed independently by two observers. For EF, inter- and intraobserver
correlations ranged from 0.94-0.98. EF was higher in the RAO than the LAO
projection (mean 47.4% vs 40.3%, p less than 0.001), but neither injection
site nor bolus FWHM affected the results. For PTT, interobserver
correlations ranged from 0.75-0.93 and intraobserver correlations from
0.61-0.85. Variability in PTT was large, and inter- and intraobserver
variabilities were directly related to bolus FWHM (mean 0.60 +/- 0.21
second for interobserver differences in PTT of less than 2.0 seconds, mean
1.55 +/- 0.86 seconds for interobserver differences in PTT of greater than
2 seconds [p less than 0.005]). Differences in FWHM between sequential
studies were 0.28 +/- 0.29 second when intraobserver differences in PTT
were less than 2 seconds and 1.04 +/- 0.67 seconds when differences in PTT
were greater than 2.0 seconds (p less than 0.005). Variations in PTT were
not related to differences in projection or injection site. Wall motion was
highly reproducible for both projections. In the RAO projection, one of 116
anterior segments (0.9%), one of 116 apical segments (0.9%), and four of
116 inferior segments (3%) were judged normal from one observer's images
and abnormal from another. In the LAO view, discrepancies occurred in one
of 126 septal segments (0.8%), two of 126 apical segments (1.6%) and four
of 126 posterolateral segments (3%). This study shows that EF and wall
motion are highly reproducible in any projection, but the choice of
projection significantly affects the values for EF from FPRA. PTT
measurements are less reliable, highly bolus dependent, and their use in
clinical practice depends on quality control of the bolus of injected
radionuclide.
