Diagnostic Imaging - Ultrasonography
Ultrasonography is fast becoming one of the most useful diagnostic tools in veterinary medicine. At Westbridge Veterinary Hospital, we offer on site ultrasonography almost every day that we are open. Two of our veterinarians have completed continuing education courses in the science of echosonography.
Echosonography is divided into two basic fields of study; general purpose and cardiology. It is very important that the machine that is used to perform Ultrasonography is capable of doing both well. These are called “dual function” machines.
Image quality also directly reflects upon the ability to make quick and accurate diagnoses. This ability relates directly to the components and software built into the unit.
At Westbridge, we believe that the addition of this service is a benefit to the speedy care and attention to our patients.
Case Study: Abdominal Ultrasonography
Ultrasonography is widely used in veterinary medicine to assess the condition of many organs in different areas of the body. A veterinarian concerned with a pet’s liver, pancreas, or kidneys, for example, can look at these areas in detail. An ultrasound examination of the digestive tract, adrenal glands, lymph nodes, urinary bladder, eyes, thyroid gland, masses and blood vessels can provide important diagnoses. The only major limitations to ultrasound are the depth of the tissue to be scanned and if there is air/gas in the area.
The ultrasound has pre-set settings which make imaging of different tissues more efficient and precise. For example, one pre-set could be indicated for the kidney of a cat, while another could be for the pancreas of a dog.
This is an ultrasound image of the liver (below). The arrows outline the presence of a small elliptical mass within the organ. This area can be biopsied to indentify it further. With the pet under anesthetic, a biopsy involves passing a small needle into the mass, guided by the ultrasound. Samples from the biopsy are sent to the lab to obtain a diagnosis. See Biopsy below.
Color flow of blood through a kidney is illustrated in the image below. Blood flow helps assess a diseased section of the tissue, and helps to identify tumours. Doppler analysis of the blood flow’s velocity in an organ can give information regarding its overall health.
Below is a collage with the ultrasound image to the left and the actual diseased tissue on the right. Note the strong correlation between the two views of the same structure. This US study found an intestinal tumor in a cat that was successfully removed.
Case Study: Cardiac Ultrasonography Echocardiograms
Echocardiograms of the heart are invaluable in the diagnosis of cardiac disease in both dogs and cats. An examination allows us to evaluate the heart in both still images and while actively beating in real time. This translates into watching the heart valves in action looking for any defects. We can calculate the volume of blood being ejected with each beat of the heart. We can even approximate the velocity of the blood being ejected at each valve. Please refer to the images below for further detail.
FIGURE 1: Here are two images which represent the left side of the heart. The mitral valve is open on the left image and closed on the right. This view is very useful in the initial visual assessment of heart function. In this modality (called the B mode), the heart is imaged in real time motion, giving the sonographer a view of the heart as it goes through each beat!
FIGURE 2: Here is another method of evaluating the heart called the M mode. The sonographer selects a specific area across the heart on the right hand image. This is then interpreted to show the motion of the heart as a continuous moving trace on the left hand image. The sonographer then compares the measurements of the filling and emptying phases of the heart cycle to normal values. These values help to diagnose heart disease, and assist in treatment.
FIGURE 3: Color (Color Doppler) is used to visualize the directional flow of blood and turbulence, if it is present. The image above demonstrates blood flowing through a defect in a closed valve. It is seen as a colored blue jet. The green and yellow speckling within suggest a turbulent flow at the level of the valve’s walls. This offers a clear interpretation of the valve’s defect.
FIGURE 4: A fourth method of examining the heart by echosonography is through audio Doppler measurements. In this method the sonographer selects a gateway area within the heart and LISTENS to the flow of blood. The ultrasound unit then creates a pattern for the flow of blood through this gate and calculates its flow rate. This is important to know when analyzing areas of narrowing (or stenosis).
Case Study: Raspberry Biopsy Demonstration
One of the most common applications in Ultrasonography is the ultrasound guided biopsy. A biopsy is a procedure by which a sample is taken for diagnosis from a mass or organ such as kidney or liver. Often a final diagnosis may only be reached when a histopathologist at a laboratory reads a biopsy sample. Ultrasonography allows for a minimally invasive approach to obtaining tissue samples. This may avoid further exploratory surgery, and the resultant complications, once the diagnosis has been reached. This is of particular importance when a pet is already severely debilitated with a serious condition. Gaining a biopsy by ultrasound may avoid a prolonged surgery and anesthesia.
FIGURE 1: This is an ultrasound image of a fruit, the common raspberry, found below in Figure 3. This demonstration shows the fine detail of the fruit as seen with a 14 mega hertz linear probe.
FIGURE 2 (left):
FIGURE 3 (right): Here is the same raspberry with a biopsy punch entering the fruit. The biopsy punch is outlined exiting the object by 4 arrows on the ultrasound image (Fig 2). This demonstration illustrates how the ultrasound gives us pinpoint accuracy for a biopsy. Because of this, often only a short acting anesthetic is required, and a very small surgical incision. Most animals can go home the same day!
