Richard A.P. Takx and Csilla Celeng
CT image acquisition
• Retrospective ECG gating without dose modulation generates high-quality images of the hearth throughout the cardiac cycle. Nevertheless, it is accompanied by a high radiation dose at around 12 mSv (Figure 3.1.1; see also Chapter 1.5).
• Alternatively, functional information can be acquired retrospectively at 20% tube current within an adjustable part of the cardiac cycle (i.e. ECG tube current modulation), while 100% tube current can be used selectively for the evaluation of the coronary artery tree. This results in a significantly lower radiation dose (Figure 3.1.1).
• Contrast enhancement for ventricular function can be achieved using different protocols such as a triphasic or an individualized split-bolus technique. It is important to limit the contrast media dose while obtaining sufficient contrast opacification of the left ventricle (LV; and right ventricle (RV)). For LV functional analysis there is no need to amend the standard coronary angiography protocol.
• In order to extract functional information, endocardial contours have to be traced by postprocessing software in end systole (ESV) and end diastole (EDV) for both ventricles. Delineation is usually performed (semi-) automatically, but contours should be visually inspected and corrected if needed.