Comparison between thallium-201 and technetium-99m-tetrofosmin uptake with sustained low flow and profound systolic dysfunction.
Technetium-99m-tetrofosmin uptake was compared to that of 201Tl in the setting of low flow and systolic dysfunction.


METHODS
In nine open-chested dogs, a severe left anterior descending (LAD) coronary artery stenosis resulted in a 54.3% mean flow reduction and decreased left ventricular thickening from 21% +/- 1% to -3 +/- 2%. After 30 min, 37 MBq (1 mCi) of 201Tl and microspheres were injected and initial and 2-hr redistribution images acquired. Two hours later, 370 MBq (10 mCi) of 99mTc-tetrofosmin and microspheres were injected and an image was obtained. LAD: left circumflex (LCX) count ratios for both tracers and flows were calculated by well counting postmortem, and 201Tl and 99mTc-tetrofosmin defect magnitudes were determined by quantitative image analysis.


RESULTS
LAD:LCx flow ratios were similar during 201Tl and 99mTc-tetrofosmin injections (0.48 +/- 0.04 versus 0.49 +/- 0.05, p = n.s.). Final 201Tl activity (0.66 +/- 0.04) was significantly higher than 99mTc-tetrofosmin (0.55 +/- 0.05; p < 0.05). LAD/LCx 99mTc-tetrofosmin image defect count ratio was similar to 201Tl defect count ratio on the initial rest 201Tl scan (0.57 +/- 0.03 versus 0.56 +/- 0.02, p = ns), but significantly less than 201Tl defect count ratio at 2 hr (0.57 +/- 0.03 versus 0.65 +/- 0.02, p < 0.05).


CONCLUSIONS
In a low-flow model with profound systolic dysfunction, myocardial 99mTc-tetrofosmin uptake ( > 50%) reflective of viability was observed in the asynergic zone perfused by the stenotic LAD.
Koplan
B A
BA
Department of Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Beller
G A
GA
Ruiz
M
M
Yang
J Y
JY
Watson
D D
DD
Glover
D K
DK
D000818:Animals; D003326:Coronary Circulation / Q000502:physiology; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004285:Dogs; D006321:Heart / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted; D008863:Microspheres; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D013599:Systole / Q000502:physiology; D013794:Thallium Radioisotopes; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D013794:Thallium Radioisotopes; C078700:technetium tc-99m tetrofosmin