Page 343 - Feline diagnostic imaging

22.3 Gastric Disorders 351

(a) (c)

(b)

Figure 22.4 Radiograph showing megaesophagus in a 7-year-old spayed female domestic longhair with a history of recent
intermittent regurgitation and lifelong upper respiratory noises. Megaesophagus was attributed to polyneuropathy of unknown cause.
Myasthenia gravis was excluded. (a) Lateral projection. (b) Right lateral projection. (c) Ventrodorsal projection. The esophagus (arrows)
contains air and some food.

in the day or even the next day. A less commonly used tech- foreign bodies [12], radiography was successful in identify-
nique is to place gas in the lumen of the stomach (pneu- ing a foreign body in only six out of 16 small animals with
mogastrogram) to try to outline a foreign object. The GI a confirmed foreign body but ultrasonography identified a
series should be followed until most of the barium is in the foreign body in all 16. Gastrointestinal foreign bodies may
colon. If significant barium is still present in the stomach have a distinct black acoustic shadow although not all
while most is seen in the colon, a cloth foreign body should exhibit acoustic shadowing.
be suspected. Cloth foreign bodies will cause retention of Characteristics of the near interface and the shape can
barium in the stomach although barium will be seen leav- help characterize an object [13]. Some objects, such as
ing the stomach normally. rocks, sewing needles, an acorn, and some rubber balls,
Ultrasound can be useful to discover foreign bodies are strongly reflective, causing them to have a hypere-
(Figure 22.6d,e) but reverberation artifact (“dirty acoustic choic near border and deep acoustic shadowing. Other
shadow”) caused by gas can easily hide foreign objects. objects are less reflective and are consequently less echo-
Scanning can be done from the ventral aspect with the genic but may still exhibit some acoustic shadowing.
patient in a standing position to try to avoid scanning Rubber toys have been reported in this category. The
through gas. Oral fluid could also be given to try to sur- shape of the near interface can be helpful. A sewing nee -
round an object. In a study comparing radiography and dle has a straight smooth margin while the margin of a
ultrasonography for identification of gastrointestinal ball is curved. Some objects transmit sufficient sound to