Fig. 4

Image quality of the uncorrected stress-test SPECT images of the 50-patient subcohort. The image quality at different myocardial signals was scored by seven nuclear physicians. Black crosses and gray error bars, respectively, indicate the average and standard deviation of the image quality scores recorded by the physicians. The orange, yellow, and green areas indicate poor (score < 33), intermediate (score 33–66), and good (score > 66) image quality, respectively. The gray curving line represents the logarithmic regression of the data. The black landmarks show how the chosen MS threshold of 22,000 counts corresponds to the expected image quality. An image quality score of around > 70 signifies good image quality