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Volume 115, Issue 10
Radiography is an integral diagnostic tool in companion animal practice. Here are brief guidelines for obtaining the most useful images of the abdomen in dogs and cats.
Radiography can help evaluate the size, shape, and position of abdominal organs and is crucial to the diagnosis of a host of conditions involving the intestines, bladder, and other abdominal organs in companion animals. Acquisition of diagnostic images using appropriate technique is crucial for accurate patient evaluation. Although a full discussion of the nuances of obtaining abdominal radiographs is beyond the scope of this article, following are some tips for obtaining excellent images while promoting patient comfort.
Although a single lateral and a single ventrodorsal (VD) projection will allow for diagnosis of many intra-abdominal conditions, it is highly recommended that both right and left lateral images be obtained in addition to a VD projection. Besides allowing for a broader evaluation of intra-abdominal contents, repositioning the patient to obtain the contralateral view allows for gas—an important contrast medium—to be redistributed for more thorough radiographic evaluation.
In most cases, a dorsoventral projection is not advised, especially as a replacement for the VD projection, because positioning for dorsoventral views can cause bunching of the abdominal contents, which can hinder appropriate evaluation and proper diagnosis. It is important to ensure that all abdominal contents are included in the fields of view. Failure to do so could lead to a misdiagnosis.
Although many digital radiology systems allow for postcapture labeling of images, it is best to place image markers into the images in real time as they are being obtained.
Proper limb positioning will help to ensure that the contents to be imaged are not obscured. Troughs and other cushions designed for use with imaging systems can be helpful to position patients properly and relieve discomfort during the image capturing process. This is particularly true for obtaining VD images, as positioning without a trough can place pressure on the spine, causing patient discomfort.
In most cases, all of the abdominal contents for review can be imaged with a single VD, right lateral, and left lateral view. However, in some larger patients, obtaining additional films (eg, 2, right lateral images) may be necessary to fully image all of the abdominal contents. It is important to ensure that additional images are continuous with the images made prior and do not skip or miss any abdominal contents.
With the patient in a lateral recumbent position, extend the thoracic limbs cranially and the pelvic limbs caudally. Take care when doing so not to promote patient discomfort or injury. Do not pull the pelvic limbs so caudally as to approach being parallel with the spine, as this could promote bunching of abdominal contents and potentially hinder evaluation.
To obtain a lateral projection, the field of view should extend about 1 inch cranial to the level of the diaphragm and about 1 inch caudal to the level of the coxofemoral joints. Dorsally collimate the field of view to just above the spinal column, such that the spinal column is included in the field of view, and ventrally collimate the field of view to just outside the level of the body wall. In most cases, this should allow for all important abdominal contents to be included.
The borders for VD abdominal radiographs are quite similar to those for lateral projections: Extend the cranial field of view about 1 inch cranial to the level of the diaphragm and the caudal border about 1 inch caudal to the coxofemoral joints. The lateral borders should be collimated such that they are just beyond the level of the patient’s body wall on either side, including them in the field of view.
When positioning the patient for a VD projection, do not pull the limbs as to be perpendicular with the spine. This can increase abdominal tension, cause bunching of abdominal contents, and may result in patient discomfort and possibly injury. Instead, rotate the thoracic and pelvic limbs laterally such that they are not obscuring any abdominal contents, and then provide only gentle retraction cranially and caudally for the thoracic and pelvic limbs, respectively.
The use of anxiolytics and/or chemical sedatives can help relieve patient anxiety and promote less patient resistance to imaging, ultimately allowing for more diagnostic films to be obtained. All medications and chemical methods for patient management should be made after thorough patient evaluation by a veterinarian and only on the order and guidance of a veterinarian as protocols will be specific to each individual patient. A discussion of medical management options, including their role, associated risks, and possible adverse effects, should be discussed with the client prior to use.
Obtaining accurate abdominal radiographs allows for the diagnosis of myriad medical conditions and improves the quality of patient care. All staff members working with patients should be familiar with imaging guidelines, such as those discussed here.
Joseph Snock, DVM, is an associate veterinarian at Mount Laurel Animal Hospital in Mount Laurel, New Jersey. His motivation to become a veterinarian stemmed from his love for his own pets combined with interest in science. Dr. Snock is a member of the New Jersey Veterinary Medical Association and the American Veterinary Medical Association. His professional interests include emergency medicine and surgery.
Thrall D. Textbook of Diagnostic Radiology, 6th ed. Elsevier; 2012.