Does attenuation corrected SPECT improve the detection of viable myocardium?

Aim: Non-uniform attenuation correction with simultaneous transmission/emission imaging improves the detection of coronary artery disease by myocardial perfusion single photon emission computed tomography (SPECT), but there are few published data on its role in the detection of viable myocardium. Method: Subjects with chronic ischaemic left ventricular dysfunction underwent nitrate enhanced resting 99mTc tetrofosmin SPECT with simultaneous transmission imaging using two roving 153Gd line sources on a dual-head gamma camera, as well as FDG PET. The three sets of tomograms – attenuation corrected SPECT (AC-SPECT), non-corrected SPECT (NAC-SPECT) and FDG PET – were assessed semi-quantitatively using a 20-segment model and blinded to clinical and other imaging information. Results: Eleven subjects (10 males; age 68±10 years; LVEF 26.9±6.2%) were recruited. The percentages of studies rated as good quality were the same for AC-SPECT and NAC-SPECT (73% for both). The weighted kappas for segmental tracer uptake agreement between AC-SPECT and FDG PET, and between NAC-SPECT and FDG PET, were comparable (0.62 vs 0.63). The concordance rate for viability between AC-SPECT and FDG PET was 81%, whilst that between NAC-SPECT and FDG PET was 82% (difference 1%; P=0.71). Conclusion: Using FDG PET as a ‘gold standard’, AC-SPECT did not improve the detection of viable myocardium when compared with NAC-SPECT.