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

Bolus triggered

Inspiration

Lung apices through the diaphragm

Venous Phase

N/A

N/A

N/A

N/A

Delayed Phase

N/A

N/A

N/A

N/A

Scan Comments: The term triple r/o is really a misnomer because several pathologies can be evaluated using this protocol. The clinical indication for using this protocol is when optimal contrast opacification is required in both the pulmonary arteries and great vessels without resulting in beam hardening artifact from the SVC. 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 the increased cardiac motion. Cardiac calcium scoring is also routinely performed 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

Care kV (ref. kV 120)

Effective mAs

CareDose

Quality Reference mAs

240

Time (Rotation)

0.28 sec.

Average Acquisition Time

HR Dependent

Collimation

128 x 0.6 mm

Pitch Value

HR Dependent

Scan Direction

Craniocaudal

Comments: Both the pitch and the scan time will vary based upon the patient's heart rate. 120 kVp 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.

 

Reconstruction Parameters

Best Phase Heart Mag

Soft Tissue Open Field

Thin Data Open Field

Lung Open Field

Slice Thickness

0.75 mm

3 mm

 0.75 mm

3 mm

Reconstruction Spacing

0.5 mm

3 mm

 0.5 mm

3 mm

Reconstruction Algorithm

Bv38 (3)

Bv40 (3)

Bv38 (3)

Bl57 (3)

Window Width and Level

500/100

410/10

410/10

1600/-500

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. An additional smaller DFOV reconstruction that only includes the heart and aorta will increase spatial resolution of the coronary vessels.

 

Reconstruction Parameters

Multiphase Heart Mag

Coronal Open Field

Sagittal Open Field

Slice Thickness

1 mm

3 mm

3 mm

Reconstruction Spacing

0.6 mm

3 mm

3 mm

Reconstruction Algorithm

Bv38 (3)

Bv40 (3)

Bv40 (3)

Window Width and Level

500/100

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. An additional smaller DFOV reconstruction that only includes the heart and aorta will increase spatial resolution of the coronary vessels.

 

Contrast Parameters

Parameters

Contrast Type

Non-ionic

Contrast Volume

120 mL

Saline Flush

30 mL (80% non-ionic contrast/20% saline)

Injection Rate

5 mL/sec.

Oral Contrast

N/A

Contrast Volume

N/A

Comments:Bolus tracking is ideal with 230 HU 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.