Objective: To compare the influence of different iodinated contrast media with several dilutions on plaque attenuation in an ex vivo coronary model studied by multislice CT coronary angiography. Methods: In six ex vivo left anterior descending coronary arteries immersed in oil, CT (slices/collimation 6460.625 mm, temporal resolution 210 ms, pitch 0.2) was performed after intracoronary injection of a saline solution, and solutions of a dimeric isosmolar contrast medium (Iodixanol 320 mgI ml
21) and a monomeric high-iodinated contrast medium (Iomeprol 400 mgI ml Invasive conventional coronary angiography is considered the standard method for the evaluation of vascular lumen and stenoses of coronary artery disease (CAD). However, it is a technique that does not allow direct assessment of the coronary artery wall and plaque composition, which is considered to be a pivotal determinant of acute coronary events [1][2][3]. Intravascular ultrasound (IVUS) allows accurate qualitative and quantitative assessment of coronary atherosclerotic plaques [4]. However, IVUS is an invasive and expensive technique. CT coronary angiography (CTCA) is now widely implemented in the clinical routine [5], especially in patients at intermediate pretest probability of CAD [6]. Several studies comparing CTCA with IVUS have demonstrated the high potential of CTCA for coronary plaque imaging purposes [7][8][9]. It has been shown that CTCA has the potential to detect atherosclerotic plaques [10,11], to quantify their volumes [12], to characterise their composition (based on the X-ray attenuating properties of each structure [13]), and to assess positive remodelling of walls [14]. CTCA may non-invasively provide information on the total plaque burden (calcified and non-calcified components) for individual patients with suspected CAD [15].High-iodinated contrast media (CM) are recommended for optimal coronary contrast intensity of CTCA [16]. However, several technical parameters, including CM influence, and intrinsic limitations may affect the attenuation measurements of coronary plaques [17][18][19][20][21][22]. The aim of our study was to compare two different CM with several dilutions of iodine load in the setting of coronary plaque assessment in an ex vivo model by means of CTCA.