Acquisition Phase

Phase Included

Scan Delay

Respiration Phase

Anatomical Coverage

Non Contrast

Yes

N/A

Inspiration

Carina through the apex of the heart

Arterial Phase

Yes

Test bolus or Bolus trigger

Inspiration

Carina through the apex of the heart

Venous Phase

N/A

N/A

N/A

N/A

Delayed Phase

N/A

N/A

N/A

N/A

Scan Comments: For larger patients, it is helpful to utilize a DSXXL based scan protocol that allows 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. Cardiac calcium scoring is routinely performed with a cardiac CTA to evaluate coronary artery disease (see Calcium Score protocol for scan details). All scans are performed using the ALARA principle. 3D post-processing is performed with this protocol.

 

Technical Parameters

Parameters

kVp

100 or 120

Effective mAs

CareDose

Care Dose Reference mAs

320

Time (Rotation)

0.28 sec

Average Acquisition Time

HR Dependent

Collimation

128 x 0.6mm

Pitch Value

HR Dependent

Scan Direction

Craniocaudal

Comments: Both the pitch and the scan time will vary based upon the patient's heart rate. 100kVp is used for most average size patients. ECG dose modulation is always performed to limit patient exposure. CareDose is used to reduce patient dose.

 

Reconstruction Parameters

Soft Tissue

Thin Data

Lung

Slice Thickness

 3mm

 0.75mm

 3mm

Reconstruction Spacing

 3mm

 0.5mm

 3mm

Reconstruction Algorithm

 B30f

 B26f ASA / I41f

 B80f

Window Width and Level

 500/100

 500/100

 1600/-500

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. Iterative reconstructions are also performed. Open field reconstructions are also performed to evaluate for extra cardiac pathology.

 

Contrast Parameters

Parameters

Contrast Type

Non ionic

Contrast Volume

80-100ml

Saline Flush

30ml

Injection Rate

5-7sec

Oral Contrast

N/A

Contrast Volume

N/A

Comments: Test Bolus is used to calculate the peak contrast enhancement to determine the correct scan delay. Bolus tracking can be used for patients with high heart rates (85bpm<).


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.