Non-coronary artery disease indications

Chapter 3.1 Ventricular volume and function


Richard A.P. Takx and Csilla Celeng



Teaching points



• Accurate measurement of left (LV) and right (RV) ventricular volume, mass, and function (including global and regional wall motion, as well as thickening) is feasible with cardiac CT.


• Retrospective electrocardiogram gating is the most common method for functional analysis. Tube current modulation allows for a significantly lower radiation dose.


• Quantification is based on endo- and epicardial contours.


• RV volume requires homogeneous enhancement of the cavity.


CT image acquisition



• Traditionally, retrospective electrocardiogram (ECG) gating is used for the acquisition of functional data sets.


• 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.


• Ideally, images should be obtained at 10% (5% with the latest-generation scanners) of the RR interval, with a 512 × 512 matrix, and a slice thickness/increment of 0.9 mm/0.45 mm.





image


Figure 3.1.1 Different CT acquisition methods with electrocardiogram gating for function.


Quantification



• 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.


• Ejection fraction (EF; in %) is calculated as (EDV – ESV)/EDV × 100


• Epicardial contours of the LV will provide information on mass and wall motion.


• Papillary muscles are usually considered as part of the LV cavity (Figure 3.1.2).


• Most software packages provide measurement of ESV, end-EDV, stroke volume, EF, myocardial mass, and wall motion.


• If needed, these values can be indexed for body surface area.

Related posts:

  1. Training and competence in cardiac CT
  2. Technical background, patient preparation, and quality and safety
  3. Indications: coronary artery disease
  4. Flu with Recent Onset of Congestive Heart Failure

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Aug 22, 2023 | Posted by in CARDIOLOGY | Comments Off on Non-coronary artery disease indications

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