Abstract: Ultrasonography is gaining importance in private veterinary practice as a diagnostic tool. Unfortunately, there are few qualified radiologists in these practices to interpret ultrasound images for practitioners. We can compensate for this by learning standard ultrasonography techniques and using remote radiologists for interpretation of scans. Veterinary technicians can increase their worth to a practice by learning these techniques. Acquiring the ultrasound image requires training, but you do not need to be a veterinarian to be a good ultrasonographer. Since it is not uncommon for no one in the veterinary practice to have experience with ultrasound, the technician can learn at the same time as the veterinarian and thus be prepared to make use of an exciting advance in veterinary medicine.
For part II of this topic, participants were from a wide variety of ultrasound diagnostic experiences, equipment sales, small and large animal use, novice, and experienced. The chat was open forum format for questions on ultrasound use. Unfortunately, weather interfered and ended the chat prematurely so, other pointers and information have been provided by the host after the chat. [?=Question, A=Answer, C=comment]

Summary:
Ultrasonography is gaining importance in private veterinary practice as a diagnostic tool. Unfortunately, there are few qualified radiologists in these practices to interpret ultrasound images for practitioners. We can compensate for this by learning standard ultrasonography techniques and using remote radiologists for interpretation of scans. Veterinary technicians can increase their worth to a practice by learning these techniques.
Acquiring the ultrasound image requires training, but you do not need to be a veterinarian to be a good ultrasonographer. Since it is not uncommon for no one in the veterinary practice to have experience with ultrasound, the technician can learn at the same time as the veterinarian and thus be prepared to make use of an exciting advance in veterinary medicine. If a technician who can perform ultrasound imaging joins a practice without an ultrasound, he or she may increase the likelihood that the practice will invest in an ultrasound machine. Understanding and using ultrasonography are valuable skills.

THE STANDARD APPROACH: In the first meeting, we discussed the basics of ultrasound physics. Knowing how the image is produced and what the image on the screen represents is the first step in performing ultrasound exams. Knowing how to manipulate that image is the second step.

Transducer selection, size: most ultrasound machines are equipped with a 3, 5, and 7.5 MHz probe. Large animal practices and newer ultrasound machines may also have a 10 MHz transducer.
The larger the number, the higher the frequency of sound waves emitted from the probe (7.5 millions of cycles per second versus 3 million cycles per second).
The higher the frequency, the greater the resolution of the picture, but the less depth of penetration. So, for example, 10 MHz would be used for tendon exams on horses or to get better detail in very small animal echocardiography, a 7.5 MHz for cats and small dogs, a 5 MHz for average size dogs, and a 3 MHz for very large dogs and/or deep structures.
Transducer selection, type:
A sector transducer (round probe) has a small contact area on the body and produces a pie-shaped image. This type is good for cardiac scans as it can go in between ribs and lung lobes, and for abdominal scans as it can go in between bubbles of gas in the intestine.
The linear transducer (rectangular probe) has a larger contact area and produces a rectangular image; it can be used for large animal scans.

Elizabeth: The basics summarized from the questions of these participants:
+Ultrasound waves are created when electrical impulses are transformed by piezoelectric crystals into sound waves that travel at a certain frequency (higher than what we can hear).
+The u/s transducer is named for the speed of sound it transmits, i.e. 3, 5, 7 and 10 MHz (millions of cycles per second)
+Higher frequencies produce better images, but don't transmit as deeply into tissues as lower frequencies. You might choose a 10 MHz transducer for a horse tendon, a 3 or 5 MHz for a big dog liver
+There are two types of transducer (shapes): linear transducers are wide and create a rectangle picture that h as a wider near-field than a sector transducer. Sector transducers create a pie-shaped picture and are good for things like looking in between ribs to image the heart; the near field is narrow and spreads out as it gets deeper.
+Sound doesn't pass through air, which makes air the "enemy" in ultrasonography this is why we shave patients, because hair holds air and will interfere with transmission. This is also why we use coupling gel, because it creates a direct connection between the probe tip and the patient
+Bone and air are "strong reflectors," meaning that sound waves bounce off of them. This makes them appear white on the u/s image because the sound wave is 100% returned to the probe tip.
+It is the returned or reflected sound waves that create " whiteness" on the screen; poor reflectors do not return sound to the probe and appear black on the screen, i.e. fluids (sound passes right through them). Most solid tissues are made up of some mass and some fluid, which gives them varying gray colors
+The reflection is called "echogenicity" anechoic is black (waves have traveled completely through them) hypoechoic is dark gray compared to other tissues hyperechoic is lighter gray or whiter compared to other tissues.

Questions/Comments:
C: On the frequencies, if they are labeled 5 can they really get quality images at 9 or 10?
Elizabeth: Do you mean when frequencies are changeable in a transducer?
A: yes Elizabeth: When you switch from close frequencies such as 3 to 5 or 5 to 7, that seems to be effective.
?: Do you anesthetize most of your patients or do them awake?
Elizabeth: Awake, although some cardiac u/s exams can go on for an hour or so and the animals get impatient!
?: We do quite a bit of ultrasound-guided FNB. Do you have any pointers that you have found helpful?
Elizabeth: FNAs for masses, organs, centesis, etc?
A: Mainly liver samples and any masses found.
Elizabeth: What technique do you currently use?
A: We use a 22ga needle on an extension set with a 12 cc syringe at the other end. The needle is inserted and a short in and out motion is used until the hub shows flash.
Elizabeth: Good, do you aspirate or prefill the syringe with air?
A: Prefill the syringe
Elizabeth: Do you get diagnostic samples using this technique?
A: Most of the time. We usually stain a slide here before sending out to see if it's diagnostic.
Elizabeth: It might be helpful to do a little bit of aspiration on the prefilled syringe, i.e. if you fill it to 6cc with air, aspirate to 7, 8, or 9 cc during the collection.
?: How do we get the "good pictures" on abdominal ultrasounds especially? The doctor does the ultrasounds with the tech restraining, but also helping interpret and discussing what they are seeing.
Elizabeth:
1. With abdominal u/s it may be helpful to wait awhile after the animal has eaten so that the stomach is not filled with food.
2. If you encounter gas in the intestines you can rock the patient back and forth to try and move the bubbles
3. Fasting the patients is not necessary, but don't feed them right before the exam.
4. Shave the area and use coupling gel--some people spray with alcohol before applying the gel, but most manufacturers don't recommend alcohol only, as it may cause eventual damage to the probe tip.

Further information (provided by the host after weather stopped the remainder of the chat):
Control knobs:
+Power: increase or decrease the intensity of the sound waves leaving AND returning to the transducer.
+Gain: increases the returning sound waves.
+Time-Gain Compensation: echoes returning from structures closer to the probe (more shallow) will be stronger and quicker to bounce back than images returning from farther away (deeper). Increasing the gain as the time of return increases will result in a more uniform image.
+Depth: controls the transmit zone or depth of the image displayed (can be adjusted, for example, if you want to see a deeper or a more shallow image.
+Contrast: controls the number of colors in the image. High contrast is more black and white; low contrast has more shades of gray.
+Freeze: saves a single frame
+Cine: for scrolling back through multiple single frames--not all machines have this.
+Calipers: for taking measurements on displayed images. The trackball can also be used (trace) to take odd-shaped measurements.
Orientation of image and scanning planes:
+There is a notch on one side of each transducer. You should hold the transducer in your hand so that the notch is at the top or on the right side. A corresponding notch (mark) appears on the left side of the ultrasound display (the screen).
+When the patient is in dorsal recumbency, for abdominal scanning, the longitudinal view is obtained with the notch on the transducer pointing up; the left side of the screen is toward the head (cranial) and the right side of the screen is toward the tail (causal). The cross-sectional view is obtained with the notch on the transducer pointing right; the left side of the screen is toward the right side of the patient and the right side of the screen is toward the left side of the patient (this is known as the left/right invert). Each structure should be scanned and measured in two planes.
+When the patient is in right lateral recumbency for cardiac exam, holding the probe with the notch at the 8 o'clock position will usually produce a cross-sectional or short-axis view. The longitudinal or long-axis view is produced by rotating the probe 90 degrees from the position used to obtain the short-axis view (i.e. from 8 o'clock to 11 o'clock).
Probe movements:
+Pressure: should be steady but not excessive. Once contact is made between the probe and the patient, increasing the pressure will not improve the image.
+Sliding: moving the probe left, right, up, or down to change the area that is being viewed. Should be done with the probe held in a flat, upright position.
+Rotation: turning the probe in a circular movement while staying in the same location, i.e. by moving the notch from 12 o-clock to 3 o-clock with the probe held in one location, you will go from a longitudinal plane to a transverse or cross-sectional plane traveling through many oblique planes. This changes the orientation of the view or the plane of the image.
+Fanning (Rocking): tilting the probe. This changes the angle of the view, i.e. from 0 to 10 and so on, enabling you to see multiple "slices" of tissue.
Artifacts: Phenomenon such as acoustic shadowing (a dark or anechoic area beneath a strongly reflective tissue), distal enhancement (area beneath a less dense structure appears more dense), mirror images (which occur at a highly reflective surface such as the diaphragm), and reverberation of sound waves (caused by an air-fluid interface) create artifacts on the image display, making it difficult to evaluate the structures that are being altered by them. You must recognize these artifacts both so that you can learn how to avoid them and so that you do not mistake them for real pathology.

General Rules/Tips: In order to increase the quality and consistency of your scans, do the following:
1. Do the scan in a dimly lit room to avoid light reflections off of the screen.
2. Remove hair from the skin and use lots of gel to increase contact and avoid artifacts.
3. Use the same positions, usually dorsal recumbency with the head away from you for abdominal scans and right lateral recumbency with the head to your left for cardiac scans.
4. Always use the proper orientation (know--and label--where left, right, cranial, and causal are).
5. Go slow, identify and label every structure imaged. Label any abnormalities identified.
6. Scan and measure every organ in two perpendicular planes. Use the same technique for every exam (i.e. quadrant approach or organ approach).
7. Record your scans on videotape for review by the veterinarian, radiologist, client, and/or other technicians in the learning process. Save the videotape, printed images, or an ultrasound report form for the medical record.

Abdominal ultrasound:
+ Performed with the patient in dorsal recumbency.
+ Fasting overnight prior to the scan may be helpful, but is not necessary. Avoid feeding the animal within a few hours of the ultrasound if possible.
+ Scan and take measurements in each quadrant or organ in succession. Any abnormalities should be described by their size, location, and echogenicity.
The veterinarian may want to perform an ultrasound-guided biopsy of a suspect lesion, so be sure to bring any to his or her attention before the animal is released from the hospital.
Some indications for abdominal ultrasound include the following: abdominal mass palpated, organomegaly, elevated liver or kidney enzymes, suspected pancreatitis, suspected lower urinary tract disease, suspected pyometra, pregnancy, or cryptorchidism, FUO or vomiting/diarrhea of unknown origin, peritoneal effusion, etc.

Echocardiography:
+ Performed with the patient lying in right lateral recumbency on an imaging table, which has a hole or window cut out so that the imager can apply the transducer to the recumbent or down side of the chest (because the heart falls closer to the transducer and lung size is decreased).
+ A simultaneous EKG reading should be taken for timing systole and diastole when making measurements.
+ The transducer is placed in a parasternal (to the side of the sternum) location just above the cardiac apex (base). This location can be found by feeling for the strongest cardiac impulse. The short- and long-axis views are obtained from this position. In the short-axis view of the cardiac apex (apical view), the right and left ventricles can be seen.
Fanning cranially, views obtained are: mid-ventricle (papillary muscle level), ventricles below the AV valve (chordal level), through the mitral valve (mitral valve level), and through the pulmonic valve/aortic valve/left atrium (aortic valve level). Rotating 90 degrees, the long-axis or longitudinal view is obtained. A 4-chamber view includes the left ventricle/mitral valve/left atrium and right ventricle/tricuspid valve/right atrium.
Fanning dorsally, the left ventricular outflow region is seen (left ventricle/aortic valve/aorta).
M-mode measurements are taken of the heart from various angles at systole and diastole. M-mode or motion-mode is a one-dimensional view through a slice of the heart and shows the movement of cardiac tissues during contraction.
Routine measurements that should be taken include:
LVDD (left ventricle dimension during diastole)
LVDS (left ventricle dimension during systole)
LVWTS (left ventricular posterior wall thickness during systole)
LVWTD (left ventricular posterior wall thickness during diastole)
IVSS (intraventricular septum thickness during systole)
IVSD (intraventricular septum thickness during diastole)
Ao (diameter of aorta) LA (diameter of left atrium)
Calculations: Fractional shortening (LVDD-LVDS)/LVDD LA:Ao (LA/Ao)
Some indications for cardiac ultrasound include the following: heart murmur, cardiomegaly, arrhythmia, suspected cardiac neoplasia, mediastinal mass, cyanosis, diaphragmatic hernia, etc. The practitioner can obtain information about the structure, function, and size of the heart chambers via standard 2-D echocardiography and information about the velocity and direction of blood flow through the heart with Doppler echocardiography (not discussed here).

Telemedicine: A board certified radiologist can review your ultrasound scans from a remote location using a telemedicine system. Images from the ultrasound are saved into your computer and then transmitted to a referral center via modem. Alternatively, real-time interactive consultations can be performed with videoconferencing technology. Thus, expertise in interpreting ultrasounds is not necessary.
Skill in obtaining the correct images becomes the limiting factor. This skill is fairly easily obtained via training and experience. Store-and-send systems are more affordable for most practitioners, and, although reading still images selected from a real-time exam is less desirable, providing the radiologist with certain standard images is a reasonable alternative.
Correct case information and images are vital to the radiologist and can make the diagnostic difference.
Views to submit:
Kidneys, 6 views of each - 3 longitudinal (sagittal) including pelvis (with measurement), lateral to pelvis and medial to pelvis, and 3 transverse (cross-section) including pelvis (with measurement), cranial to pelvis and causal to pelvis.
Liver - 7 longitudinal views (caudate lobe + right kidney, vena cava + hepatic veins, gall bladder, cystic/common bile duct, L lateral lobe, L medical lobe, liver + spleen) and 2 cross-sectional views (one including gall bladder).
Spleen - 5 longitudinal views (including splenic vein, lateral to splenic vein, medial to splenic vein, spleen + liver, spleen + L kidney) and 3 cross-sectional views (including splenic vein, cranial to splenic vein and causal to splenic vein).
Pancreas - 4 longitudinal views (including duodenum, ventral-medial to R kidney, causal aspect of pyloric antrum, causal aspect of body of stomach and 3-4 cross-sectional views (1-2 including duodenum, ventral-medial to R kidney, causal to stomach).
Adrenal glands - 1 sagittal and 1 transverse image of each gland, or, if they are not clearly visualized, 2 sagittal views (between cranial pole of R kidney and vena cava, between cranial pole of L kidney and aorta) and 2 transverse views (including cranial pole of R kidney and vena cava, including cranial pole of L kidney and aorta).
*Also include labeled images of any masses, lesions, etc.
**There are also standard views to submit for ultrasonography of the bladder, stomach, intestines, prostate, heart, etc. Consult your radiologist for details.

Conclusion: The usefulness of ultrasound in practice is highly imager and image dependent. The ultrasonographer has to be able to achieve diagnostic images if an ultrasound diagnosis is to be made. Poor technique and poor images are the main reasons why ultrasound fails. Training is vital! Textbooks can also be very useful in understanding the image controls, how images are obtained, and various pathologies.

Participants: Elizabeth (host), Anne, Curtis, Danielle, Geri