Table 1. Summary of cardiac CT technique factors.
| Technique factors | Considerations |
|---|---|
| Spatial resolution | Up to 0.35 mm |
| Optimize for detailed evaluation of small structures (i.e., coronaries) | |
| Temporal resolution | Up to 66 milliseconds in a third-generation dual source scanner |
| Optimize to reduce cardiac motion artifact | |
| ECG gating | Prospective: evaluation of coronary arteries; requires slow and regular heart rate (<60 beats per minute); lower radiation |
| Retrospective: functional information, wall motion assessment, LVAD evaluation; allows for greater heart rates; higher radiation | |
| Medications | Heart rate control: beta blockers (oral, intravenous) |
| Coronary vasodilation: nitrates (sublingual) | |
| Contrast protocol | Biphasic protocol: opacify left heart and coronaries without contrast on RV or SVC |
| Triphasic protocol: opacify both right and left heart chambers without SVC streak artifact | |
| Dose reduction | Prospective ECG triggering (regular/high pitch) |
| High pitch helical mode | |
| ECG-based tube current modulation (retrospective) | |
| Body part-dependent tube current modulation | |
| Body habitus-based low kVp or mAs | |
| Thicker slices | |
| Iterative reconstruction algorithms |
CT, computed tomography; ECG, electrocardiogram; LVAD, left ventricular assist device; RV, right ventricle; SVC, superior vena cava; kVp, kilovoltage peak; mAs, milliamperage-seconds.