Page 92 - Atlas of Small Animal CT and MRI

82 Atlas of Small Animal CT and MRI

Figure 1.5.18 Orbital Rhabdomyosarcoma (Canine) MR

(a) T1, DP (b) T2, DP (c) T1+C+FS, DP

(d) T1, DP (e) T2, DP (f) T1+C+FS, DP

(g) T2, TP (h) T1+C+FS, TP
3y MC Tibetan Terrier with a 2‐week history of left‐sided exophthalmos. Representative dorsal plane images are at (a–c) and ventral to
(d–f) the level of the eyes. There is a large irregularly shaped mass within the retrobulbar space (a–c,g,h: asterisk), which is isointense
to gray matter on both T1 and T2 images. The mass invades the left temporal muscle (a–c: arrow) and appears to cause osteolysis of the
left zygomatic bone (d,h: arrowheads). The mass is nonuniformly contrast enhancing. Incidentally, the optic chiasm and origins of the
optic nerves are particularly well seen in this study (e,f: arrow), and the origin of the left optic nerve does not appear to be involved.
Histologic diagnosis following necropsy was rhabdomyosarcoma.

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