Carina through the apex of the heart
Apex of the lungs through the diaphragm
Scan Comments: This protocol was created using the Siemens DSXXL_Chest_PainECG scan parameters, which allow for the temporal resolution to be adjusted even after the scan has been completed. Increasing the temporal resolution times will allow for a reduction in image noise at the expense of increased cardiac motion. Typically, a sequential calcium score is also performed (see sequential calcium score protocol for scan details). All scans are performed using the ALARA principle.
Care Dose Reference mAs
Average Acquisition Time
128 x 0.6mm
Comments: Both the pitch and the scan time will vary based upon the patient's heart rate. 120kVp is necessary to limit beam hardening artifact from occurring at the SVC, which can obstruct pathology on the great vessels. ECG dose modulation is always performed to limit patient exposure. CareDose is used to reduce patient dose.
B26f ASA / I41f
Window Width and Level
Reconstruction Comments: A 1.0mm x 0.6mm multiphase reconstruction is generated across the ECG pulsing range every 5-10% of the R-R interval. An additional smaller DFOV reconstruction that only includes the heart/aorta will increase spatial resolution of the coronary vessels. Iterative reconstructions are performed to improve image noise. Coronal and sagittal image reconstructions are also performed.
30ml (80% nonionic contrast/20% saline)
Comments: Bolus tracking is ideal with 230HU trigger value on the ascending aorta. A diluted flush (80% contrast to 20% saline) is used to soften the SVC and limit beam hardening artifact.
Other Comments: Selecting the correct range for ECG dose modulation is based primarily on the patient's heart rate and clinical indication. When multiphase images are not clinically indicated, the use of ECG dose modulation, specifically Siemens MinDose application, can significantly reduce the patient's exposure. See Cardiac CT Flow Chart below for more information on selecting the correct protocol based on the patient's heart rate and rhythm. Coronary CTA images should visualize the coronary arteries and left ventricle with adequate opacification of IV contrast. Images should limit venous contamination while flushing contrast out of the right ventricle to prevent image artifacts.