Page 109 - Atlas of Small Animal CT and MRI

Salivary Glands 99

of the normal architecture of the gland. Examples enhancement (Figure 1.7.12), and MR hyperintensity
include adenocarcinoma of the mandibular (Figure 1.7.9) on T2 images with hypointensity on T1 images
and parotid (Figure 1.7.10) salivary glands, as well as (Figure 1.7.13). The fluid compartments may exhibit
zygomatic basal cell adenocarcinoma (Figure 1.7.11) peripheral contrast enhancement on CT and MR
images. The location of the fluid in relation to the sali-
Sialolithiasis and sialocele vary glands may suggest a gland of origin. For example,

When the salivary ducts are blocked by mucus fluid in the sublingual region is likely associated
concretions or sialoliths, the production of saliva causes with obstruction to the sublingual salivary duct
expansion of cavities within the salivary gland, which (Figure 1.7.13). Sialoceles may also occur bilaterally,
extend beyond the normal borders. These fluctuant appearing as roughly symmetric fluid‐filled masses on
masses tend to contain fluid in large thin‐walled both sides of the mandible (Figure 1.7.14). If sialoliths
chambers in the ventral mandibular area, sublingual are responsible for the ductal obstruction, they may be
region, or orbit (see zygomatic sialadenitis earlier in seen on CT images within the fluid of the mass, within
this chapter). The communication with the salivary the ipsilateral or contralateral gland, or within the duct
gland may be difficult to localize on CT and MR images. itself (Figure 1.7.15). Sialoceles may also form in other
Other imaging characteristics include fluid that is salivary glands, including minor glands that are less
hypoattenuating on CT (0 HU) with no contrast commonly seen on imaging examinations. 4

Figure 1.7.1 Normal Parotid and Mandibular Salivary Glands (Canine) CT

(a) CT+C, TP (b) CT+C, TP (c) CT+C, TP

(d) CT+C, SP
6y MC Boxer. Representative images were acquired immediately following contrast medium administration and are ordered from rostral to
caudal. The normal mandibular salivary glands are characteristically oval in shape and smoothly margined (a–d: arrows). The normal parotid
salivary glands are more elongated and have lobular margins (a–c: arrowheads). Both glands are highly and uniformly contrast enhancing.
The major sublingual salivary gland is a small triangular structure fused to the cranial margin of the mandibular salivary gland (d: open arrow).
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