Dynamic acquisition with a three-headed SPECT system: Application to technetium 99m-SQ30217 myocardial imaging

A method for SPECT data acquisition, 'continuous repetitive rotation acquisition,' was developed with a high-sensitivity three-headed SPECT system. The method was applied to the dynamic imaging of ^99mTc-SQ30217, a new myocardial imaging agent. After acquisition and reconstruction of SPECT data every minute, projection images at arbitrary intervals were used for tomographic reconstruction to determine the best timing of SPECT imaging in ^99mTc-SQ30217. Based on a comparison of several possible acquisition intervals, SPECT data acquisition within 9 min after injection is recommended because of high myocardial uptake (myocardium-to-lung ratio, 2.83 ± 0.42 (mean ± s.e.m.) at 3-6 min) and relatively low hepatic uptake (myocardium-to-liver ratio, 0.85 ± 0.13 at 3-6 min). The rate constant of the clearance of ^99mTc-SQ30217 from the myocardium obtained by SPECT was: k₁ = 0.249 ± 0.050 per min (average half-life = 2.8 min) and k₂ = 0.012 ± 0.004/min (average half-life = 58 min). The continuous repetitive rotation acquisition SPECT study appears useful for imaging SQ30217 with its rapidly changing myocardial distribution.