| Background: The aim of this study was to assess the influence of the iodine concentration on vessel attenuation in non-invasive 16-slice computed tomography coronary angiography (coronary CTA). Method: Eighty consecutive patients were randomized into two groups for contrast medium (CM) administration: group A with 85ml of standard contrast medium (Iopamidol 300, Bracco, Italy) and group B with 69 ml of high-concentration contrast medium (Iopamidol 370, Bracco, Italy). Both were injected at a flow rate of 3.5ml/s. All patients underwent retrospectively ECG-gated coronary CTA (Somatom Sensation 16, Siemens, Forchheim, Germany). The attenuation in Hounsfield units (HU) was measured at eight regions of interest (ROI), including the root of the ascending aorta (AAO), right coronary artery (RCA), left main coronary artery (LM), left anterior-descending branch (LAD), left circumflex branch (LCX), left ventricle (LV), right ventricle (RV) and the coronary sinus (CS). Furthermore two additional parameters LV/RV and AAO/CS were calculated. Differences were evaluated with the Student's t test.Results: The average attenuation in AAO was greater in group B (344 HU) than in group A (304 HU), with the difference of 40 HU (p <0.01). Similar results were also found in RCA, LCA, LAD and LCX. While in RV the average attenuation of group B (169 HU) was 42 HU lower than that of group A (211 HU)(p<0.01). No significant difference between the two groups was found in LV and CS (p>0.05 ). The additional parameters LV/RV and AAO/CS displayed higher for group B (p<0.01). Conclusion: Given the same total iodine content, CM with high concentration provides higher attenuation of the coronary arteries as well as the aorta and less attenuation in the right cavities of the heart. It therefore improves the utilization of CM and optimizes the bolus geometry in coronary CTA. |
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