Carotid body detection on CT angiography

Abstract

Background and purpose: Advances in multidetector CT provide exquisite detail with improved delineation of the normal anatomic structures in the head and neck. The carotid body is 1 structure that is now routinely depicted with this new imaging technique. An understanding of the size range of the normal carotid body will allow the radiologist to distinguish patients with prominent normal carotid bodies from those who have a small carotid body paraganglioma.

Materials and methods: We performed a retrospective analysis of 180 CTAs to assess the imaging appearance of the normal carotid body in its expected anatomic location.

Results: The carotid body was detected in >80% of carotid bifurcations. The normal size range measured from 1.1 to 3.9 mm ± 2 SDs, which is consistent with the reported values from anatomic dissections.

Conclusions: An ovoid avidly enhancing structure at the inferomedial aspect of the carotid bifurcation within the above range should be considered a normal carotid body. When the carotid body measures >6 mm, a small carotid body paraganglioma should be suspected and further evaluated.

Fig 1.

Representative axial CTA images demonstrate the method of orthogonal measurements, which were performed bilaterally.

Fig 2.

Oblique sagittal reformations were performed with a B20 kernel at a 2-mm thickness and at 2-mm increments. The normal carotid body is seen at the carotid bifurcation.

Fig 3.

Bar graph shows the distribution in size of the carotid body based on measurements of 358 carotid bodies. The right carotid body measures an average of 2.4 (transverse) × 2.0 (AP) ± 0.8 (transverse) and 0.6 (AP) mm. The left carotid body measures, on average, 2.2 (transverse) × 2.1 (AP) ± 0.7 (transverse) and 0.5 (AP) mm. The range of normal defined as 2 SDs is 1.1–3.9 mm for the carotid body.

Fig 4.

Line graph shows that the Pearson coefficient of the transverse dimension of the right carotid body to the left is 0.52 with a P value of <.0001. The data indicate a correlation between the AP and transverse dimensions of the right and left carotid bodies.

Fig 5.

Line graph shows that the Pearson coefficient of the AP dimension of the right carotid body to the left is 0.43 with a P value of <.0001. This illustrates a correlation between the size of the right and left carotid bodies.

Fig 6.

Axial CTA image depicts an avidly enhancing mass at the right carotid bifurcation splaying the internal (white arrow) and external carotid arteries (black arrows). There are numerous central and peripheral enlarged feeding arterial branches within this carotid body tumor.

Fig 7.

Axial CTA exhibits a small enhancing structure at the left carotid bifurcation, corresponding to a normal carotid body.