Avoid radiographic errors in your veterinary cases: Obtain multiple views

November 8, 2018
Eli Cohen, DVM, DACVR

Eli Cohen, DVM, DACVR, is a clinical assistant professor of radiology at North Carolina State Universitys College of Veterinary Medicine and co-owner of Dragonfly Imaging, PLLC.

It's easy to be convinced of a diagnosis by a single two-dimensional image. Get the whole picture by obtaining additional angles.

As a boarded radiologist and experienced teleradiologist, Fetch dvm360 conference speaker Eli Cohen, DVM, DACVR, has seen his share of problematic diagnostic images. The trouble starts, he says, when you flatten a patient's 3D anatomy into a 2D frame. So, whether you're dealing with thoracic, abdominal or musculoskeletal cases, he has one overarching piece of advice: Obtain more views.

"We have to have an orthoganal view just to place things in space, much less make a diagnosis," he says.

While Dr. Cohen says some diagnoses may be made with only a lateral radiograph, there's the risk of being "rewarded for bad behavior," as he puts it.

"Maybe you make a diagnosis on that lateral radiograph but didn't appreciate what else you might have seen," he says. "So you sort of get a false sense of confidence that that single view is giving you more than it really is."

Help a teleradiologist out

In his capacity as a consulting teleradiologist, Dr. Cohen has occasionally received less-than-precise instructions as to what he's supposed to be looking for ... in the radiographs sent to him.

"[Lack of clinical context] makes life as a teleradiologist really difficult and inherently decreases the predictive value of that test because we don't know what you're looking for," he says.

Take a look at this video for his tips on getting the most out of the consultation proces.

The solution, he says, is a three-view series of images-right-lateral, left-lateral, and either ventrodorsal or dorsoventral views. This goes well beyond redundancy. Dr. Cohen considers each view a separate test, pointing to one simple reason-gravity.

Consider the thorax: Positioning patients in different recumbencies can cause the lungs, for example, to present differently. If this "dynamic airbag" is in the wrong orientation, the resulting radiograph can be physically distorted and cause elements to essentially disappear.

And it's not just incidental things you might miss, he says: "Severe pneumonia, cancer nodules, masses-those things can be virtually invisible on a single view in the down lung as that lung becomes atalectic, which will be very conspicuous on the other views."

Dr. Cohen says this can be the difference between making a diagnosis and sending a sick pet out the door.

Influence of right versus left lateral recumbency

In the video below Dr. Cohen mentions a study of "different positioning and order of radiographs." He's referring to "Initial influence of right versus left lateral recumbency on the radiographic finding of duodenal gas on subsequent survey ventrodorsal projections of the canine abdomen" by Vander Hart and Berry.

The authors write: "Results showed that dogs first placed in left lateral recumbency were significantly more likely to have duodenal gas on the subsequent ventrodorsal and right lateral radiographic projections compared to dogs first placed in right lateral recumbency. This study emphasizes the benefit of using initial left lateral abdominal projections prior to other views for subsequent evaluation of the duodenum."

Read more here.

In the case of the abdomen, he says this phenomenon of shifting gases and fluids can be used to your advantage. He cites as an example the notoriously difficult-to-analyze gastrointestinal tract.

"We want to exploit gravity and gas to help outline lesions, particularly the left-lateral view, which is essential if we want to outline and assess the pylorus for outflow tracts, obstructions, foreign bodies or masses," Dr. Cohen says.

Musculoskeletal imaging also benefits from a comprehensive series.

"You could have a completely luxated joint that you can't tell on a lateral view that would only be visible on a vetrodorsal or orthogonal view," Dr. Cohen says.

Again, the method for proper diagnosis is centered, collimated views of the area of concern, he says.

Watch the video for more.

You. Can. Do. This!

At Fetch dvm360 conference, we're the support system you need. With every conference this year, we intend to nurture your mind (meaning quality CE for days) while also encouraging you to take stock of your physical and emotional health. Register now.