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1.10

Larynx, pharynx, and neck

Introduction Inflammatory disorders

The soft tissues of the larynx, pharynx, and neck are inves- Nasopharyngeal polyps
tigated using both CT and MR imaging. Both modalities Nasopharyngeal polyps arise from the tympanic bulla
1
have excellent sensitivity for evaluation of inflammatory or auditory tube, are inflammatory in origin, and are
and neoplastic lesions when contrast medium is used. CT most often seen in cats. On CT images, they have poorly
has lower inherent soft‐tissue contrast than MR, and sen- defined margins and are hypoattenuating on unenhanced
sitivity and interpretation confidence can be increased images. Following contrast administration, masses
when the animal is scanned in the open‐mouth position, remain centrally hypoattenuating with an intensely con-
using air as additional contrast. 2 trast‐enhancing margin (Figure 1.10.4). In most cats, a
stalk connecting the polyp to the widened auditory tube
Developmental disorders can be seen. Ipsilateral or bilateral otitis media is usually
4
present as soft‐tissue or fluid attenuating material within
A laryngeal cyst causing upper airway obstruction has the bulla, which may be thickened, expanded, and
been reported in a dog. CT imaging characteristics were occasionally lytic. Imaging features of otitis media are
a fluid‐attenuating mass with a thin rim of contrast described in Chapter 1.2.
enhancement that did not communicate with the laryn-
geal lumen. 3 Foreign bodies

Trauma Inflammation of the pharyngeal region often occurs
secondary to foreign bodies within the nasopharynx
Trauma due to bite wounds or other direct insult to or penetrating foreign bodies from the skin or phar-
the neck and laryngeal region may cause disruption ynx that localize in the neck or retropharyngeal region.
of the hyoid apparatus at its attachment to the skull Unless they are of sufficient size, plant material foreign
or its intrinsic joints. Symmetry of the hyoid appara- bodies are often not directly visualized on CT or MR
tus is helpful in determining whether disruption images. Larger foreign bodies, such as sticks, may have
has occurred, both on transverse and 3D images a definite shape and exhibit internal architecture. On
5,6
(Figures 1.10.1, 1.10.2). Trauma may also result in MR images, the foreign bodies may be isointense
hematoma formation that causes a mass effect with on T1 and hypointense or hyperintense on T2 images.
characteristics of blood or proteinaceous fluid on MR On CT images, the foreign material may be hyperat-
images (Figure 1.10.3). tenuating. There is surrounding tissue and edema that is

Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
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