Separate or simultaneous rest 201Tl/stress 99mTc-sestamibi dual- isotope SPECT are potentially efficient myocardial perfusion imaging protocols which combine the use of a high-resolution 99mTc tracer for stress perfusion assessment and 201Tl, the current single-photon agent of choice, for viability assessment. Methods: To investigate the feasibility of dual-isotope myocardial perfusion SPECT protocols using rest 201Tl and stress sestamibi, 201Tl crosstalk into the 99mTc acquisition window (Group 1, n = 26 patients) and 99mTc crosstalk into 201Tl windows (Group 2, n = 25) were studied. For Group 1, treadmill exercise with sestamibi injection and poststress SPECT ('virgin' sestamibi images) were performed, followed by rest 201Tl injection and SPECT acquisition using dual-isotope windows (contaminated or 'dual' images). For Group 2, the order was reversed: rest 201Tl SPECT (virgin 201Tl images) was performed first, followed by exercise sestamibi injection and dual-isotope SPECT. Results: The contribution of 201Tl scatter to the dual sestamibi images (Group 1) was measured to be 2.9% ± 2.1%, while 99mTc crosstalk contributed 26.7% ± 13.0% to the dual 201Tl images (Group 2). Image quality was considered good to excellent in 92% of the sestamibi (virgin and dual) images and 88% of the virgin 201Tl SPECT, but only in 23% of the dual 201Tl studies. Conclusions: Technetium-99m crosstalk into 201Tl windows is substantial; therefore, simultaneous dual-isotope protocols, which involve assessment of 201Tl images contaminated by 99mTc, are not recommended. On the other hand, because of the small amount of 201Tl crosstalk into the 99mTc window, a separate acquisition dual-isotope approach employing the rest 201Tl (virgin)/stress sestamibi sequence is acceptable.
|Number of pages||7|
|Journal||Journal of Nuclear Medicine|
|Publication status||Published - 1994|
- dual-isotope imaging