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 triggered

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 protocols for scan details). All scans are performed using the ALARA principle. 3D post-processing is performed with this protocol.

 

Technical Parameters

Parameters

kVp

120

Effective mAs

CareDose

Care Dose Reference mAs

320

Time (Rotation)

0.28 sec (flex)

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. 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

Best Phase

Thin Data

Thin Data

Multiphase

Slice Thickness

 3 mm

0.75 mm

 0.75 mm

1 mm

Reconstruction Spacing

 3 mm

0.5 mm

 0.5 mm

0.6 mm

Reconstruction Algorithm

B26f ASA

B26f ASA

I41f (3)

I26f (3)

Window Width and Level

500/100

 500/100

 500/100

500/100

Reconstruction Comments: A 1.0 mm x 0.6 mm multiphase reconstruction is generated across the ECG pulsing range every 5-10% of the R-R interval. Open field reconstructions are also performed to evaluate extra cardiac pathology.

 

Reconstruction Parameters

Lung

Soft Tissue Open Field

Thin Data Open Field

Slice Thickness

 3 mm

3 mm

 0.75mm

Reconstruction Spacing

 3 mm

3 mm

 0.5 mm

Reconstruction Algorithm

B80f

B30f

B20f

Window Width and Level

1600/-500

410/10

410/10

Reconstruction Comments: A 1.0 mm x 0.6 mm multiphase reconstruction is generated across the ECG pulsing range every 5-10% of the R-R interval. Open field reconstructions are also performed to evaluate extra cardiac pathology.

 

Contrast Parameters

Parameters

Contrast Type

Non ionic

Contrast Volume

80-100ml

Saline Flush

30ml

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.