Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

458 Small Animal Radiolo g y and Ultrasono graphy
Fig. 3-280 A 9-year-old female
domestic short-haired cat with
vomiting for 1 day. The lateral
radiograph revealed two focal areas
of calcification cranial to the kidneys
(black arrows). Diagnosis:
Calcification within the adrenal
glands.
Fig. 3-281 A 10-year-old female
Cocker Spaniel with polyuria and
polydipsia for 2 months. There was a
pendulous abdomen and mild
alopecia. Survey radiographs were
within normal limits. A pneumoperitoneum
was performed. The
horizontal beam lateral radiograph
shows the abdominal gas surrounding
the retroperitoneal structures.
The left kidney (black l) and right
kidney (black r) are clearly demonstrated.
A third tissue-dense structure
(black a) is seen superimposing
the area where the two renal shadows
overlap. Diagnosis: Left adrenal adenocarcinoma.
sonographic characteristics ranging from hypoechoic to hyperechoic. These characteristics
correlated with their histologic architecture. 920,924 Mineralization of the adrenal
gland may produce hyperechoic areas that form shadows. 34 These may be associated with
adrenal tumors or may be seen in normal-aged animals. Adrenal tumors may invade into
or entrap the caudal vena cava or aorta, and this may be observed during the ultrasonographic
examination. 924 However, it may be difficult to distinguish between compression
and invasion of the vena cava by ultrasonography or by nonselective angiography.
Alteration of the normal blood flow may be detected using Doppler ultrasonography.
Computed tomography also has been shown to be a useful adrenal imaging modality. 927
For cases with equivocal status (e.g., compressed versus truly invaded by the adrenal
mass) of the regional great vessels in anticipation of a surgical decision, a composite
interpretation is best, one that includes the nonselective venogram, the ultrasonogram
and, if possible, a contrast-enhanced computed tomogram.