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

Top of the head through the entire aortic vasculature

Venous Phase

N/A

N/A

N/A

N/A

Delayed Phase

N/A

N/A

N/A

N/A

Scan Comments: This protocol is used to evaluate the vasculature of patients with connective tissue disorders to r/o aneurysm, dissection or vascular anomaly. The protocol is often modified and limited to a specific area of interest. A Flash spiral protocol is used to limit patient motion artifacts, specifically cardiac motion over the aortic root. Additionally, the fast scan times are important when the patient is short of breath or a limited volume of contrast is needed.  All scans are performed using the ALARA principle. A 3D Post Processing is performed with this protocol.

 

Technical Parameters

Parameters

kVp

120 or 140

Effective mAs

140

Care Dose Reference mAs

N/A

Time (Rotation)

0.28 sec

Average Acquisition Time

1-2 sec

Collimation

128 x 0.6mm

Pitch Value

1.6

Scan Direction

Craniocaudal

Comments: A fixed mAs setting is used to limit noise and artifact, specifically in the brain. For large patients, 140 kVp may be necessary with a reduced effective mAs to maintain image quality.  We prefer to keep the pitch lower (less than 2.5) when scanning through the abdomen. This will avoid increased image noise or spiral artifact while still minimizing both cardiac and breathing motion.   

 

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: When using Flash spiral mode, the DFOV is limited by the smaller of the two detector arrays to 33.2cm. This limitation can be overcome by reducing the pitch value to allow for a greater DFOV. Coronal and sagittal image reconstructions are also performed.

 

Reconstruction Parameters

Head

Neck

Neck Bone 

Slice Thickness

5mm

3mm

3mm

Reconstruction Spacing

5mm

3mm

3mm

Reconstruction Algorithm

I30f

B30f

B70f

Window Width and Level

100/30

350/50

2500/500

Reconstruction Comments: Additionally, a soft tissue thin data set of the neck is performed using 0.75 mm x 0.5 mm slices, a B20f algorithm, and a window width and level of 350/50.

 

Contrast Parameters

Parameters

Contrast Type

Non ionic

Contrast Volume

80-100ml

Saline Flush

N/A

Injection Rate

5-6ml/sec

Oral Contrast

H2O

Contrast Volume

1000ml

Comments: Bolus tracking is performed on the aortic arch using a 60HU trigger setting.