Two-position supine/prone myocardial perfusion SPECT (MPS) imaging improves visual inter-observer correlation and agreement

We aimed to compare the inter-observer agreement between two experienced readers using supine vs combined supine/prone myocardial perfusion SPECT (MPS) in a large population. 1,181 consecutive patients without known coronary artery disease (CAD) undergoing rest Tl-201/stress Tc-99m-sestamibi MPS studies were evaluated. Visual reads were performed in two consecutive steps, with readers scoring the stress supine perfusion images during step 1 and rescoring the images using both supine/prone data during step 2. Visual summed stress scores (SSS) of two readers including regional scores in different vascular territories were compared. The specificity for both readers improved using combined supine/prone imaging (reader 1: 92% vs 86% [P = .0002], reader 2: 88% vs 72% [P < .0001]). The inter-observer correlation for SSS (0.90 vs 0.84, P < .0001) and inter-observer agreement for combined supine/prone reading (bias = 1.0, 95% confidence interval (CI) 0.9-1.2 vs bias = 3.1, 95% CI 2.8-3.4, P < .0001) were significantly better as compared to supine-only reading. The overall correlation between SSS scores for two readers improved with supine/prone imaging for both genders, as well as in the left anterior descending and right coronary territories. The inter-observer correlation and agreement significantly improve using two-position supine/prone vs supine-only imaging.