Acquisition Phase

Phase Included

Scan Delay

Respiration Phase

Anatomical Coverage

Non Contrast

N/A

N/A

N/A

N/A

Arterial Phase

Yes

Bolus triggered

Inspiration

Apex of the lungs 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 flash spiral mode is most successful when imaging patients with heart rates 60-70bpm. Utilizing this mode will result in extremely low dose exams. All scans are performed using the ALARA principle. A 3D Post Processing is performed with this protocol.

 

Technical Parameters

Parameters

kVp

100 or 120

Effective mAs

CareDose

Care Dose Reference mAs

360

Time (Rotation)

0.28 sec

Average Acquisition Time

1-2 sec

Collimation

128 x 0.6mm

Pitch Value

3.2

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 to R interval of the ECG wave. 100kVp is used for most average size patients. ECG dose modulation is not necessary for this protocol.

 

Reconstruction Parameters

Soft Tissue

Thin Data

Lung

Slice Thickness

 3mm

 0.75mm

 3mm

Reconstruction Spacing

 3mm

 0.5mm

 3mm

Reconstruction Algorithm

 B30f

 B20f

 B80f

Window Width and Level

 410/10

 410/10

 1600/-500

Reconstruction Comments: There is a limited reconstruction field of view when using the flash spiral mode to 33.2cm.  Iterative reconstructions are also performed to improve image noise. An additional smaller DFOV reconstruction that only includes the heart/aorta will increase spatial resolution of the coronary vessels. Coronal and sagittal image reconstructions are also performed.

 

Contrast Parameters

Parameters

Contrast Type

Non ionic

Contrast Volume

80-100mL

Saline Flush

30mL

Injection Rate

5-7mL/sec

Oral Contrast

N/A

Contrast Volume

N/A

Comments: Bolus tracking is used ideal with a 300HU trigger value on the ascending aorta. A saline flush can be used to soften the SVC and limit beam hardening artifact.

 

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.