## 3 Materials and Methods  
### CAD Dataset  
Patient data have been acquired from the Diagnostic Medical Center \"Diagnostiko-Iatriki A.E.\" in Larisa, Greece, by the Nuclear Department and have been retrospectively examined. The study covers a period from 30 March 2012 to 28 February 2017. Over this period, 842 consecutive patients underwent gated-SPECT MPI with 99 mTc-tetrofosmin. A hybrid SPECT/CT gamma-camera system (Infinia, Hawkey-4, GE Healthcare (Chicago, USA)) was used for MPI imaging. Fifty-six (56) patients were excluded from the dataset due to inconclusive MPI results. Our dataset includes a total of 625 patients, of which 127 correspond to infarction, 241 to ischemic, and 257 to normal. The images have been extracted with the SPECT method and illustrate a visual representation of the heart in rest and stress modes.  
Two nuclear medicine experts ([PERSON] and [PERSON]) were asked to label each instance of the dataset according to their expertise and experience. The nuclear medicine experts count several years of experience (approximately 15 and 25 years, respectively). The experts completed the labeling using solely the MPI scans from each patient. This way, the model could be directly compared with the human experts. Hence, this study uses the experts' diagnostic yield as the ground truth and aims to furnish a DL model capable of competing with the human eye and expertise. The ethical committee for our institution approved the study. The nature of the survey waives the requirement to obtain patients' informed consent. In Figure 1, we provide a representation of all cases.  
The followed protocol included a 1 day stress-rest injection of Tc-99m tetrofosmin for SPECT imaging. Symptom-limited Bruce protocol treadmill exercise testing (\(n\) = 154 [69%]) or pharmacologic stress (\(n\) = 69 [31%]) were applied to the patients, while radiotracer was injected at peak exercise or during maximal hyperemia, respectively.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Clinical Characteristics** & **Frequency** \\ \hline No & 625 \\ Age (mean \(\pm\) SD) & 62.2 \(\pm\) 7.8 years \\ Sex (male/female) & 65.88\%/34.22\% \\ History of CAD & 40.89\% \\ Previous Myocardial Infarction & 35.48\% \\ Previous Stroke & 13.46\% \\ Hypertension & 70.25\% \\ Smoking & 58.18\% \\ Diabetes & 40.56\% \\ \hline \hline \end{tabular}
\end{table}
Table 1: Clinical characteristics of the corresponding dataset.  
Figure 1: Image samples of coronary artery disease: (**a**) Infarction; (**b**) ischemia; (**c**) normal.  
Stress SPECT images were collected in the first 20 min after injecting 7 to 9 mCi 99 mTc-tetrofosmin in both medical processes (effort test or pharmacological stress with dipyridamole). Concerning the effort test, patients underwent a treadmill test based on the Bruce protocol and were injected 99 mTc-tetrofosmin when the age-predicted maximum heart rate achieved at least 85%, allowing 1 min before the end of the test. During the rest process, a dose of 21-27 mCi 99 mTc-tetrofosmin was injected into patients, allowing 40 min for rest imaging to be performed. In particular, 32 projections of SPECT MPI were carried out in a period of 30 s for the stress and 30 s for the rest, before the SPECT system delivered the data. A 140 keV photopeak, a 180 degree arc, and a 64 \(\times\) 64 matrix were among the configurations that were additionally set up.  
This study was approved by the board committee director of the diagnostic medical center \"Diagnostiko-Iatriki A.E.\", Dr. [PERSON]. The director of the diagnostic center waived the requirement to obtain informed consent due to its retrospective nature. All procedures in this study were in accordance with the Declaration of Helsinki.