Does attenuation-corrected spect improve the detection of viable myocardium?

Abstract Background: 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. Methods: Subjects with chronic ischaemic left ventricular dysfunction underwent nitrate-enhanced resting 99m Tc-tetrofosmin SPECT with simultaneous transmission imaging using two roving 153 Gd line sources on a dual-head gamma camera, as well as 18 F-2-fluorodeoxyglucose positron emission tomography (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 segmental model, and blinded to clinical and other imaging information. Results: 11 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 versus 0.63). The concordance rate for viability between AC-SPECT and FDG-PET was 81%, while that between NAC-SPECT and FDG-PET was 82% (difference 1%; p=0.71). Bland-Altman analysis revealed a mean difference between AC-SPECT and FDG-PET segmental percentage tracer uptake of +2.21%, with a standard deviation of 17.1%. This did not differ significantly from the mean difference between NAC-SPECT and FDG-PET of −0.4±18.3%. Conclusion: In this pilot study, using FDG-PET as a gold standard, AC-SPECT did not improve the detection of viable myocardium when compared with NAC-SPECT.