Page 70 - Atlas of Small Animal CT and MRI

60 Atlas of Small Animal CT and MRI

Figure 1.4.7 Masticatory Myositis (Canine) MR
8y FS Golden Retriever with a 2‐week history
of weight loss, stridor, cranial nerve deficits,
and temporal muscle atrophy. Bilaterally
symmetrical temporal muscle atrophy is evi-
dent on all sequences. There is marked, diffuse,
and symmetrical hyperintensity of temporal
(c: large arrows), masseter (c: small arrows),
and pterygoid (c: arrowheads) muscles on the
T2 and STIR images corresponding to regional
enhancement on the contrast‐enhanced T1
image (b). A similar diffuse T2 hyperintensity
and contrast enhancement pattern of the
laryngeal tissues is evident (b: arrow).
Necropsy revealed severe, bilateral, chronic,
(a) T1, TP (b) T1+C, TP and diffuse lymphoplasmacytic myositis with
myonecrosis and myodegeneration. This dog
also had laryngeal cellulitis.

(c) T2, TP (d) ST, TP

Figure 1.4.8 Temporal Muscle Abscess (Canine) CT

9y FS Chow with pain when opening mouth.
A focal draining lesion was seen in the caudal
oral cavity. The contrast‐enhanced image
shows a poorly delineated cavitary lesion
within the left temporal muscle, consistent
with an intramuscular abscess (b: arrow).
Peripheral contrast enhancement extends to
the medial surface of the coronoid process of
the left mandible and to the external surface
of the left parietal bone, but overt bone reac-
tivity is not appreciated. Fascial and muscle
contrast enhancement is also evident ventrally
(b: arrowheads), indicative of more diffusely
distributed cellulitis. Biopsy revealed chronic
(a) CT, TP (b) CT+C, TP suppurative cellulitis.

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