Table 1.

Differential diagnosis table for carotid body tumor

Diagnosis	Ultrasound findings	CT findings	MRI findings	Angiography/DSA findings
Carotid body tumor	Well-defined hypoechoic mass that splays the carotid bifurcation; hypervascular with low-resistance flow pattern	A mass with soft tissue density; heterogeneously enhancing at the carotid bifurcation in the early arterial phase; strong and rapid enhancement	Nestled between the external and internal carotid arteries; signal intensity is nearly similar to muscle on T1-weighted, and hyperintense signal on T2-weighted; salt and pepper sign appearance	Splaying of the carotid vessels; the ascending pharyngeal artery is the main contributing supply; conventional angiography can demonstrate vascular anatomy
Carotid artery aneurysm	“Yin-Yang” sign; pseudoaneurysm or dissection can occur	Change in the diameter of the blood vessel	An oval, irregular, or slit-like cross section of the vessel lumen	Delineate extension, detect stenosis
Carotid artery pseudoaneurysm	A hypoechoic cystic structure adjacent to the true vessel; color Doppler imaging present “to and fro” flow and bidirectional Doppler waveform in pseudoaneurysm neck	CT can demonstrate the vessel wall irregularity and irregular outpouching; compatible with rupture and active bleeding	MRI with T1-weighted fat-suppressed sequences allows for evaluation of intraluminal thrombus and pseudoaneurysm sac size	DSA remains the gold standard for evaluation of pseudoaneurysm
Neck hematoma/ thrombus	Dilated and incompressible arterial, intraluminal clot, and no response to arterial maneuver	On non-enhanced CT, hematoma appears as a high-density mass. On enhanced CT, it does not enhance with contrast agent	Hemorrhage on MRI has highly variable imaging characteristics that depend on the age of the blood. On T2-weighted, acute thrombus of the arterial will have a high intensity, whereas subacute arterial thrombus will have a low signal	May locate the active arterial bleed/source of hemorrhage
Glomus vagale tumor	May be seen as a solid heterogeneously hypoechoic lesion comprising of small vascular structures	A mass with soft tissue density; heterogeneously enhancing	Usually low signal on T1-weighted; high signal with multiple flow voids on T2-weighted; intense contrast enhancement on T1-gado	Same carotid body tumor but tends to displace the carotid artery anteriorly
Schwannoma	Permitted direct visualization of the vagus nerve, so its position relative to the schwannoma could be examined; can result in an increase of the distance between the artery and vein (separation)	A mass with soft tissue density; non-enhancement of the mass on contrast-enhanced	Well-encapsulated tumors appear as a round or ovoid mass that is isointense to muscle on T1-weighted, hyperintense on T2-weighted; nerve sheath tumors that may or may not enhance	Tends to displace both vessels together rather than splaying them