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: The Adaptive Sequence mode is very useful when imaging patients with irregular heart rates to avoid reconstruction artifacts. 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

Care kV (ref. kV 120)

Effective mAs

CareDose

Care Dose Reference mAs

288

Time (Rotation)

0.25 sec (flex)

Average Acquisition Time

HR Dependent

Collimation

152 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. 100 kVp is used for most average size patients. ECG dose modulation is always performed. When using adaptive sequence, the radiation exposure can be limited to only the useful portion of the ECG wave, which will significantly reduce the radiation dose. 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

 Bv40

 Bv40 / Bf44

 BI57

Window Width and Level

 600/200

 600/200

 1600/-500

Reconstruction Comments:  A 1.0 mm x 0.7 mm 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 extra cardiac pathology.

 

Contrast Parameters

Parameters

Contrast Type

Non-ionic

Contrast Volume

80-100 mL

Saline Flush

30 mL

Injection Rate

5-7 mL/sec.

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.