Washout and redistribution between immediate and two-hour myocardial images using technetium-99m sestamibi.

The aim of this study was to assess whether a clinically relevant change in myocardial sestamibi activity could be documented within the first 120 min following injection (p.i.). In 17 patients planar anterior imaging of the heart was performed 5 min and 120 min p.i. During this time interval, mean decay-corrected myocardial activity declined to 77.9% +/- 9.7% after stress and to 85.7% +/- 7.9% after injection at rest (P < 0.05). In 19 patients with angiographically documented coronary artery disease, single-photon emission tomography was performed 5 min and 120 min after injection at maximum stress. For analysis, sestamibi activity was scored semiquantitatively in six left ventricular segments. Furthermore, sestamibi uptake was assessed quantitatively using a circumferential profile method. In 35 of 114 segments the score improved within 120 min p.i. (early fill-in); in these segments relative sestamibi activity rose from 69.9% +/- 22.5% to 74.5% +/- 20.8% (P < 0.01). In five patients this early fill-in was the only sign of exercise-induced hypoperfusion. In 7 of 114 segments the score deteriorated 120 min p.i. (early tracer washout); in these segments relative sestamibi activity declined from 85.6% +/- 9.9% to 80.1% +/- 10.7% (P < 0.02). In three of four patients with early tracer washout the corresponding coronary artery was significantly narrowed. In conclusion, a global myocardial sestamibi washout was registered within the first 120 min after injection. A fill-in of initial defects as well as an early tracer loss could be detected in a relevant number of patients with chronic coronary artery disease during the first 2 h p.i.(ABSTRACT TRUNCATED AT 250 WORDS)