Vet360 Vol 4 Issue 4 August 2017 Vet 360 - Page 27

DIAGNOSTIC IMAGING Figure 1A: This left lateral radiograph shows a foreign body (sock) within the pylorus of the stomach and the descend- ing duodenum. Note that you can barely see the linear stria- tions of the lesion on the right lateral radiograph (Figure 1B), but it is clearly seen on the left lateral when gas is present in the fundus. (Radiography images courtesy of Dr. Anthony Pease.) Figure 1B: Right lateral view. 3 Contrast studies can still be done, but think of con- trast medium like an overwhelming force—a little goes a long way. This may not make intuitive sense, as contrast medium is supposed to highlight abnormalities and is heavier than liquid so it settles, but remember that contrast medium is so opaque it will overpower and hide anything it covers. For example, consider a double-con- trast cystogram. If you put too much iodinated contrast medium in the urinary bladder, you’ll miss the stone. Also, for upper gastrointestinal tract examinations in stable pa- tients, it’s sometimes easier to see the foreign bodies four to six hours after administration of barium since the bari- um will stick to the foreign material after the rest of the barium clears (Figure 2). Just remember, if you’re going to ultrasonographically ex- Figure 1C: Ventrodorsal view. contrast with the soft tissue and fluid that may be present, especially in the abdomen. For example, in most dogs linear foreign bodies get caught in the pylorus of the stomach. A right lateral radiograph puts that side down so it’s surrounded by fluid. Therefore the soft tissue of the foreign body blends with the fluid in the stomach and you can’t see the lesion. If you’re worried about a linear foreign body, take a left lateral radiograph to put gas in the py- lorus, allowing you to see the foreign body (Figure 1). Figure 2A: This radiograph was obtained six hours after barium ad- ministration. Note all the barium is within the colon, except for a focal region in the stomach. This was a gastric foreign body (Vetrap) that was retained in the stomach. Issue 04 | AUGUST 2017 | 27