Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

306 Small Animal Radiolo g y and Ultrasono graphy
Fig. 3-65 Longitudinal sonogram of
the liver of a 13-year-old male
Schnauzer with a history of depression,
anorexia, and bloating. A hyperechoic
structure is evident in the
dependent portion of the gallbladder.
There is shadowing deep to this structure.
This represents a mineralized
gallstone. Diagnosis: Cholelithiasis.
Fig. 3-66 Longitudinal sonograms of the gallbladder of a 13-year-old spayed female Pit Bull with a
history of hematuria secondary to a transitional cell carcinoma of the bladder. The dog was undergoing
chemotherapy. There is echogenic material within the dependent portion of the gallbladder.
This changes appearance with repositioning of the dog. This is helpful in confirming that the material
is within the gallbladder and is not a slice-thickness artifact. Transverse sonograms (not illustrated)
are also important to document that the material is within the gallbladder. This represents
inspissated bile or sludge within the gallbladder. This is a common incidental finding. Diagnosis:
Inspissated material within the gallbladder.
movement of the hyperechoic structures will help discriminate between air or mineral in
the gallbladder wall or within the lumen.
Cholelithiasis may be seen as an incidental finding in many animals. 292 These stones
may be large and well defined or may consist of a “sand” or sludgelike material (Figs. 3-63,
3-65, and 3-66). 180,182,184,186,187 They may form a hyperechoic layer within the dependent
portion of the gallbladder or may be wedged within the gallbladder and remain fixed in
position. Gallstones are usually hyperechoic and may or may not cause shadows. 293
Choleliths can change their position within the gallbladder with changes in patient
position. Sludge or inspissated bile is seen commonly in asymptomatic patients.
Reverberation or slice-thickness artifacts may project echoes into the gallbladder lumen.
These can be recognized if the ultrasonographer is aware of their occurrence and uses caution
in examining the gallbladder in both longitudinal and transverse planes. The stones
may move into the common bile duct. These stones may or may not result in bile duct
obstruction (Fig. 3-67).