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 flash spiral mode is most successful when imaging patients with heart rates 60 bpm or lower. Using this mode will result in extremely low dose exams. 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

Average Acquisition Time

1-2 sec

Collimation

128 x 0.6mm

Pitch Value

3.4

Scan Direction

Craniocaudal

Comments: Using the flash spiral mode allows for greatest dose savings potential. The entire data series is collected in one heart beat thus avoiding the need for a slow pitch with multiple images across the R-R interval of the ECG wave. 100 kVp is used for most average size patients. ECG dose modulation is not necessary for this protocol. CareDose is used to reduce patient dose.

 

Reconstruction Parameters

Soft Tissue

Thin Data

Thin Data

Lung

Slice Thickness

 3 mm

0.75 mm

 0.75mm

3 mm

Reconstruction Spacing

 3 mm

0.5 mm

 0.5 mm

3 mm

Reconstruction Algorithm

B26f ASA

B26f ASA

I41f (3)

B80f

Window Width and Level

500/100

 500/100

 500/100

1600/-500

Reconstruction Comments: The reconstruction field of view is limited to 33.2cm using the flash spiral scan mode. Open field reconstructions are also performed to evaluate extra cardiac pathology.

 

Reconstruction Parameters

Soft Tissue Open Field

Thin Data Open Field

Slice Thickness

 3mm

0.75 mm

Reconstruction Spacing

 3 mm

0.5 mm

Reconstruction Algorithm

B30f

B20f

Window Width and Level

410/10

410/10

Reconstruction Comments: The reconstruction field of view is limited to 33.2cm using the flash spiral scan mode. 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 also be used.

Other Comments: To successfully scan a patient using the flash spiral mode, the heart rate should be 60-70bpm and the patient should be no larger than average size to avoid increased image noise. Typically, flash spiral gated chest acquisitions are performed with an ECG trigger of 60%. It may also be useful to trigger at 30% for patients with higher heart rates. The ECG trigger must be changed utilizing the scan protocol assistant, so it may be beneficial to build two separate protocols, diastolic and systolic, when programming the scanner.