## 2 Protocol  
The acquisition protocol of LIE-CT can vary depending on the specific clinical practice or study conducted, as well as the availability of dual-energy technology. Generally, whether involving stress CT perfusion or coronary CT angiography, the acquisition of the LIE image typically occurs 10 min after intravenous contrast medium administration, with or without minimal additional contrast medium injection [8]. Due to concerns related to radiation exposure, practitioners generally conduct the LIE-CT scan using a reduced tube voltage or tube current, or a combination of both. Although a lower tube voltage helps in enhancing the image contrast, it simultaneously leads to increased image noise, consequently impacting both the contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) [9; 10]. This constraint has been a crucial consideration in the utilization of LIE-CT. Conventional single-energy CT imaging is prone to technical challenges arising from the polychromatic nature of X-rays, including artifacts like blooming and beam hardening. The introduction of dual-energy CT (DECT) has alleviated some of these technical limitations [11]. Hence, studies employing dual-energy technology have yielded the most favorable outcomes. For instance, among the protocols proposed, in a study by [PERSON] et al., CT scans were performed using a second-generation dual-source scanner with a triphasic bolus injection of iodinated contrast medium. The injection protocol included 75 mL of contrast medium, followed by 40 mL of a mixed solution (25% contrast medium and 75% saline) and an additional 40 mL of pure saline. The choice between prospective electrocardiogram-triggering or retrospective gating depended on the patient's pulse rate. Following the CT angiography acquisition, an additional dose of contrast medium was administered promptly, with the goal of reaching a total iodine dose of 0.6 g per kilogram of body weight. The LIE scan was acquired 10 min later, using a low-voltage axial prospective scan synchronized to 75% of the cardiac cycle phase. The scan parameters included kV adjusted based on the patient's body mass index (body mass index \(<\) 30 = 80 kV, body mass index \(\geq\) 30 = 100 kV), a rotation time of 0.28 s, detector collimation of 128 mm \(\times\) 0.6 mm, a matrix size of 512 \(\times\) 512, and a display field of view limited to the heart [6]. Another example of protocol implementation comes from [PERSON] et al., who conducted a study aimed at evaluating the diagnostic performance of DECT-LIE in identifying and categorizing myocardial scars in heart failure patients, using CMR-LGE as the gold-standard reference. They employed a rapid kilovolt peak-switching 64-detector row DECT scanner. Following coronary CT angiography, an additional infusion of 0.5 mL/kg contrast media was administered for 60 s. Subsequently, a CT scan was conducted after 7-8 min with the following parameters: a tube voltage ranging from 80 to 140 kV; rapid kilovolt peak switching; a tube current set at 600 mA; a rotation time of 0.35 ms; collimation of 0.625 mm; prospective electrocardiographically gated axial scanning at the mid-diastolic phase; a display field of view measuring 180 mm \(\times\) 180 mm; and a matrix of 512 \(\times\) 512. For the quantification of the iodine density in a voxel, a two-materialdecomposition technique was employed, utilizing water as the foundational material, with the iodine density expressed as 100 ug/cm\({}^{3}\) on iodine density images [12]. Additionally, to enhance the image quality in iodine density imaging, they applied an adaptive statistical iterative reconstruction intensity of 80%, based on prior research findings. Indeed, a study by [PERSON] et al. demonstrated that employing an adaptive statistical iterative reconstruction intensity between 80% and 100% in LIE images could improve the image quality without compromising the signal integrity, thus maximizing the accuracy in determining the transmural extent in the infarcted myocardium [13].