Comparison of 111In Leakage from Labeled Endocardial and Epicardial Cells : Impact on Modeling Viability of Cells to Be Transplanted into Myocardium

Abstract EN

Introduction.

Previously we proposed a cellular imaging technique to determine the surviving fraction of transplanted cells in vivo.

Epicardial kinetics using Indium-111 determined the Debris Impulse Response Function (DIRF) and leakage coefficient parameters.

Convolution-based modeling which corrected for these signal contributions indicated that 111In activity was quantitative of cell viability with half-lives within 20 hrs to 37 days.

We determine if the 37-day upper limit remains valid for endocardial injections by comparing previous epicardial cell leakage parameter estimates to those for endocardial cells.

Methods.

Normal canine myocardium was injected (111In-tropolone) epicardially (9 injections) or endocardially (10 injections).

Continuous whole body and SPECT scans for 5 hours were acquired with three weekly follow-up imaging sessions up to 20–26 days.

Time-activity curves evaluated each injection type.

Results.

The epicardial and endocardial kinetics were not significantly different (Epi: 1286±253; Endo: 1567±470 hours P=.62).

Conclusion.

The original epicardial estimate of leakage kinetics has been validated for use in endocardial injections.