Glomerular filtration rate measured by Tc-DTPA Gates method is not significantly affected by the premature or delayed initiation of image acquisition.

BACKGROUND

This study was performed to examine the effect of non-synchronization of the radiotracer injection and image acquisition on estimates of the glomerular filtration rate (GFR) by the Gates' method.

METHODS

A total of 218 volunteers were selected as the research subjects. Two-sample method (GFR) and Tc-DTPA dynamic renal imaging (GFR) were used for determination of the GFR. We took GFR as the reference method, and then took the peak time of blood perfusion phase as the new time origin to ensure that all patients were unified on the time-radioactivity count rate curve. We moved the radioactivity curve on 9 time points to simulate premature (+20/+15/+10/+5 seconds), synchronous (0 seconds), and delayed (-20/-15/-10/-5 seconds) image acquisition in relation to the completion of tracer injection; we then acquired 9 GFR. The correlation and consistency of GFR and GFR were analyzed. Variance analysis compared the differences between different GFR.

RESULTS

All 9 GFR had good correlation with GFR. GFR and GFR derived from -5, -10 and -15 s had the best correlation (r=0.827, P<0.01). The consistency between GFR derived from +20 s and GFR was the worst, and GFR derived from -15 s and GFR was the best. There were no significant differences between the 9 GFR.

CONCLUSIONS

Non-synchronization of the radiotracer injection and image acquisition has no significant effect on the estimates of the GFR if the premature or delayed time between image acquisition and tracer injection is not more than 20 seconds.