When should a computed tomography (CT) neck angiogram be ordered, how is it performed, and what are its contraindications and alternative imaging options?

CT Neck Angiography: Indications, Performance, and Clinical Decision-Making

CT angiography (CTA) of the neck is specifically indicated for evaluating pulsatile neck masses and suspected vascular injuries from trauma, but is NOT appropriate for routine evaluation of nonpulsatile neck masses or adenopathy. 1

Primary Indications for CTA Neck

Trauma Evaluation

• CTA neck is the preferred initial screening examination for suspected cervical vascular dissection or injury, with sensitivity and specificity approaching 98%. 2
• For penetrating neck trauma, CTA serves as first-line imaging after clinical assessment, demonstrating sensitivity of 90-100% and specificity of 98.6-100%. 2
• In blunt cerebrovascular injuries (BCVI), CTA is recommended over digital subtraction angiography due to short acquisition time and low complication rate. 2
• CTA is essential for high-velocity maxillofacial trauma when clinical suspicion for vascular injury exists based on revised Denver criteria. 2
• For strangulation patients, CTA neck with IV contrast is the primary imaging modality to evaluate vascular injuries, simultaneously identifying extravascular soft-tissue and aerodigestive injuries with 100% sensitivity. 2

Cerebrovascular Disease

• CTA neck is recommended for rapid assessment of extracranial vasculature in acute ischemic stroke evaluation and endovascular surgical planning. 2
• Noninvasive imaging of cervical carotid arteries should be performed within 48 hours for patients who are candidates for carotid endarterectomy or stenting, particularly in transient ischemic attack (TIA) evaluation. 2
• CTA neck combined with CTA head provides comprehensive assessment of potential extracranial sources of thromboembolism. 2
• CTA allows detection of vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap in suspected cervical artery dissection. 2

Pulsatile Neck Masses

• CTA neck with IV contrast is usually appropriate for initial imaging of pulsatile neck masses (not parotid region or thyroid), serving as an equivalent alternative to CT neck with IV contrast, MRI neck, or MRA neck. 1
• Although CTA is optimized to visualize cervical arteries, soft tissues are usually well characterized simultaneously. 1
• Contrast is useful for distinguishing vessels from lymph nodes, as many pulsatile neck masses in level II or III are actually lymph nodes overlying the carotid artery rather than true vascular masses. 1

When CTA Neck is NOT Indicated

Nonpulsatile Neck Masses

• There is no evidence to support the use of CTA for evaluation of a nonpulsatile neck mass. 1
• For nonpulsatile neck masses, contrast-enhanced CT (not CTA) is the preferred initial imaging modality in adults, particularly considering the risk of head and neck cancer. 1

Pediatric Neck Masses

• There is no evidence to support the use of CTA for evaluation of a palpable neck mass in a child. 1

Intracranial Hemorrhage Workup

• Neck CTA is only recommended in patients with confirmed intracranial hemorrhage in a pattern consistent with aneurysm or arteriovenous shunt, not as routine screening. 3
• Although neck CTA can provide helpful information for planning catheter angiography (anatomical arch variants in 22% of cases), findings that would significantly prolong angiography occur in only 5%. 3

Technical Performance

Contrast Administration

• CTA neck requires IV contrast administration with arterial phase timing to maximize detection of vascular injuries. 2
• Thin-slice (1mm) acquisition should be used to maximize detection of small fractures and subtle vascular injuries. 2
• Multiplanar reconstructions (sagittal and coronal) should be obtained to better visualize laryngohyoid structures and cervical spine. 2

Imaging Protocol Considerations

• All imaging should reflect "as low as reasonably achievable" (ALARA) practices, with advances in lower dose protocols varying among vendors. 1
• Dual-phase CT imaging (without and with IV contrast) is not usually necessary. 1

Contraindications and Limitations

Absolute Contraindications

• Iodinated contrast requirement may be contraindicated in patients with severe renal impairment or contrast allergy. 2, 4
• Hemodynamically unstable patients with "hard signs" (active hemorrhage, expanding hematoma, airway compromise) should proceed directly to surgery without imaging. 5

Technical Limitations

• Radiation exposure is a consideration, especially for young patients or those requiring repeated imaging. 2
• Heavy calcifications can lead to overestimation of stenosis. 2
• Streak artifact from metallic foreign bodies may limit evaluation. 2

Alternative Imaging Options

MR Angiography (MRA)

• MRA is an alternative for patients with renal impairment or contrast allergy, but is limited in acute trauma settings due to longer acquisition times and potential issues with metallic foreign bodies. 2
• MRA neck is complementary to MRI in evaluation of pulsatile neck masses to achieve anatomic and vascular detail. 1
• Time-resolved (4-D) contrast-enhanced MRA technique may be useful for characterization of head and neck arteriovenous malformations. 1
• MRI of the neck is superior to CT for detecting soft tissue hemorrhages in neck musculature and should be considered when CT is negative but high clinical suspicion persists. 2

Ultrasound

• Ultrasound is limited in neck trauma due to overlying soft tissue injury and limited evaluation of zones I and III. 2
• For pediatric patients with congenital abnormalities, ultrasound is useful in differentiating solid from cystic neck lesions and discriminating high-flow from low-flow vascular malformations. 1

Conventional Angiography

• Conventional angiography is now primarily reserved for equivocal CTA findings or when endovascular therapy is planned. 2
• There is no evidence to support the use of catheter angiography for initial evaluation of neck masses. 1

Common Pitfalls to Avoid

• Do not order CTA neck for nonpulsatile neck masses or adenopathy—use contrast-enhanced CT instead. 1
• Do not order CTA neck routinely with head CTA for suspected intracranial hemorrhage unless the pattern is consistent with aneurysm or arteriovenous shunt. 3
• Do not use CTA in pediatric neck mass evaluation—ultrasound, contrast-enhanced CT, or MRI are appropriate alternatives. 1
• Do not rely on CTA alone when MRI may be needed for soft tissue injury documentation in strangulation cases, particularly for forensic purposes. 2
• Avoid ordering dual-phase imaging (with and without contrast) as this doubles radiation exposure with minimal added diagnostic benefit. 4