CT angiography of the chest (protocol)

CT angiography of the chest (CTA chest) is a cross-sectional diagnostic examination that can be performed ECG-gated or non-ECG gated.  

NB: This article is intended to outline some general principles of protocol design. The specifics will vary depending on CT hardware and software, radiologists' and referrers' preference, institutional protocols, patient factors (e.g. allergy) and time constraints. 

Indications

CTA of the chest in a wide variety of clinical scenarios including:

• aortic aneurysm
• dissection
• suspected bleed

Contraindications 

• previous severe reactions to iodinated contrast
• non-compliance

Technique

• patient position
  • supine with their arms above their head
• scout
  • above apices to below the renal arteries 
• scan extent
  • above apices to below the renal arteries 
• scan direction
  • caudocranial
• contrast injection considerations
  • monitoring slice (region of interest) 
    • descending aorta at the level of the carina
  • threshold
    • 100 HU
  • injection 
    • 75 ml of non-iconic iodinated contrast with a 100 ml saline chaser at 4.5/5 ml/s
• scan delay
  • minimal scan delay 
• ​respiration phase
  • inspiration

Practical points

• this scan is performed ECG-gated, will mitigate cardiac motion.
• the utilisation of monitoring series is highly recommended due to the differences in cardiac output between patients ¹
• when performing image reconstitutions, oblique-sagittal reconstructions of the aortic will display the entire vessel in one image