Term
| Ultrasonography can provide information about what? |
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Definition
- about organ architecture independent of organ fxn
- esp helpful in debilitated or young pts, in which the contrast agents used in special procedures or exploratory sx may be contraindicated |
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Term
| Using ultrasonography allows the ability to distinguish between what on masses seen in the organs. |
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Definition
| - allows the ability to distinguish solid masses from those containing fluid and to determine the distribution of lesions in organs |
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Term
| Explain how the ultrasonic beam works to capture the image |
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Definition
- the beam is created by a piezoelectric crystal that oscillates at several million Hertz per second (MHz) w/in a transducer (probe)
- when sound wave interacts w/ tissues in the body, it is reflected, and the echo is rec’d by the transducer
- the rec’d impulse is converted to an electronic signal and processed through a computer to become part of a composite of signals that make up the final image of the organ
- returning signals have diff intensities because tissues have diff acoustic properties or acoustic impedance |
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Term
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Definition
the different acoustic properties of tissues
- elasticity of the tissue determines the way sound interacts w/ the tissue: reflection, transmission or refraction |
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Term
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Definition
reflection
- reduced intensity of radiation caused by absorption or scattering, or both, during passage through tissue
- sound is also attenuated as it passes through tissue and the intensity is reduced
- air scatter sound
- water transmits sound w/ little attenuation, the lack of attenuation creates distant enhancement |
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Term
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Definition
- an ultrasound artifact that indicates the presence of fluid
- increased sound intensity beyond a fluid-filled, anechoic area, created by absence of attenuation of the sound beam as it passes through the fluid
- water transmits sound w/ little attenuation, the lack of attenuation creates distant enhancement |
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Term
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Definition
- a lack of echos beyond the reflecting object
- echo free zone created distal to the imaged organ when sound waves hit a highly reflective tissue that prevents sound from being transmitted to greater depths
- minerals and metals are highly reflective.
- sound cannot penetrate bone |
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Term
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Definition
- intensity of reflected echos
- is an indication of the liquid or solid composition of the tissue |
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Term
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Definition
- no echos are detected and the area is black
- typically assoc w/ fluid-filled structures such as the urinary bladder |
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Term
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Definition
- a few echos are detected and the area is low-level gray compared w/ adjacent tissues
- usually seen w/ solid homogenous tissues or complex fluid containing cells such as blood
- the medullary papillae of the kidney are hypoechoic |
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Term
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Definition
- echos produced are brighter than in surrounding tissues
- bright white echos
- bladder stones are hyperechoic |
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Term
| Why is a videotape recorder used to record images? |
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Definition
- the advantage of the videotape is the ability to capture real-time images for review
- organ motion can be assessed
- esp useful for echocardiography
- thermal printers produce high quality paper images that can be incl in the med record |
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Term
| Explain the difference between M-mode and B-mode echocardiography. |
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Definition
M-mode (motion mode)
- optimal to detect abnormal valvular motion such as fluttering, prolapse, or insufficient closure and to accurately measure chamber size and wall thickness
- info is displayed as depth vs time on a graph
- used for echocardiography
- displays cardiac wall and valvular movement as a graph over a period of time
B-mode (brightness-mode)
- intensity of returning echos is expressed as brightness in the display
- cardiac abnormalities such as pleural and pericardial effusion
- cardiac masses
- congenital anomalies such as defects in the interventricular septum |
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Term
| Is sedation required for performing an echocardiogram? |
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Definition
| - sedation is rarely necessary, proper restraint is needed |
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Term
| What areas should long axis scans include? |
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Definition
- a long-axis view is an echocardiographic image showing the heart from base to apex in a longitudinal or sagittal plane
- should incl the
left atrium
mitral valve
interventricular septum
left ventricular few wall
by slightly tipping the transducer the aortic valve and aortic root can be seen
in cats the right atrium and right ventricle are diff to see on the long-axis view when approached from the right parasternal position because the right side of the cat heart is so close to the thoracic wall and this side of the heart is often outside of the focal zone of the transducer
in dogs the right heart chambers are usually seen on the long-axis view from this position |
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Term
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Definition
- should incl strcutures from the base to the apex of the heart
aortic valve
pulmonic valve
left atrium are seen at base of heart
mitral valve next as tras is directed more toward apex
below mitral valve are the left ventricle, interventricular septum and right ventricle
four-chamber view shows the left and right atria, mitral and tricuspid valves and the right and left ventricles |
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Term
| What are two-dimensional scans helpful in identifying when performing an echocardiogram? |
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Definition
- cardiac abnormalities such as pleural and pericardial effusion
- cardiac masses
- congenital anomalies such as defects in the interventricular septum |
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Term
| What are the indications for Doppler studies of the heart? |
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Definition
| - pulmonic, aortic, mitral and tricuspid valvular insufficiencies and stenosis and congenital heart defects such as VSD and persistent ductus arteriosus (PDA) |
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Term
| For an ultrasound of the abdomen how long should the patient be fasted? |
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Definition
- non-emergency pts should be fasted for 12 hrs to reduce the amt of intestinal gas
- full bladder optimal for scanning the bladder or prostate |
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Term
| What structures of the liver are poorly visualized when performing an ultrasound? |
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Definition
- hepatic veins have poorly defined walls
- bile ducts and hepatic arteries are not well visualized in small animals and in normal animals, separate lobes can’t be identified |
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Term
| What are the primary indications for liver scanning? |
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Definition
- abnormalities seen on survey rads (hepatomegaly or a mass in the area of the liver
- elevations in liver enzymes, ascites, or suspected hepatic metastases |
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Term
| What are some indications to perform a splenic scan? |
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Definition
- mass
- diffuse enlargement or abnormal position on survey rads or palpation
- abdo trauma w/ hemorrhage, acute abdo pain, or signs of anemia and collapse
- in cases of a splenic mass (hemangiosarcoma) the liver is scanned to search for metatases |
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Term
| What is the most common indication to ultrasound the pancreas? |
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Definition
- pancreatitis
- neoplasms, cysts and abscesses are rare |
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Term
| Why can GI sonography be difficult to visualize the structures? |
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Definition
- due to variable amts of gas w/in the lumen, which reflect sound and prevent imaging of deeper structures
- also feces w/in the colon cause shadows |
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Term
| What structures can be identified when performing ultrasonography of the urinary bladder. |
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Definition
- calculim blood clots and masses from the bladder wall can be identified
- anechogenic urine
- bladder must be filled
- tumors in the bladder neck area are difficult to see and urethral masses are not visible because of pelvis location |
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Term
| What are some indications for ultrasonography on the Reproductive tract? |
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Definition
- dx pregnancy
- pyometra
- stump granuloma
- or ovarian neoplasia
- normal non preg repro tract not commonly seen in sm animals |
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Term
| What does ultrasonography examination of the extremities primarily focus on? |
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Definition
| - the equine limb below the carpus and tarsus |
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Term
| Pregnancy can be diagnosed as early as how many days in an equine? |
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Definition
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Term
| How must an equine patient be prepped for an ultrasound? |
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Definition
- area shaved and thoroughly cleaned to avoid creating artifact reflections
- coupling gel
- hair traps air and creates numerous little air pockets, there must be no air between pt and transducer to reflect sound waves |
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Term
| What is the common frequency in sound waves used for equine ultrasonography? |
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Definition
| - 2 to 10 megahertz (MHz) |
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Term
| List and describe the two basic types of transducers. |
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Definition
- There are two basic types of transducers.
- Linear array transducers have ultrasound crystals, which emit the ultrasound waves, arranged in a row. This emits ultrasound from multiple points along the transducer, producing a rectangular image
- Sector scanner transducers have one or more ultrasound crystals that rotate or oscillate to produce a pie-shaped image.
- Variations of sector scanners, such as the annular array and phased array, are also available for some machines; these are more expensive machines used mostly for cardiac studies such as color-flow Doppler echocardiography. |
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Term
| When is fetal sexing best performed? |
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Definition
- between day 60 and 75 of gestation
- sexing requires locating the genital tubercle, closer to the umbililcus in males, closer to the tail in females
- before day 60 the genital tubercle is located between the hindlimbs and has not yet migrated sufficiently to easily predict sex
- after day 75 the fetus has grown to a size and location that often prevents visualization of the genital tubercle |
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Term
| What is the proper way to maintain the ultrasound equipment? |
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Definition
- Transducers are expensive and are the most easily damaged part of an ultrasound machine. Hard impacts can damage the ultrasound crystals. The surface is susceptible to scratching from abrasive materials.
- Built-in standoffs are susceptible to punctures and cuts.
- The transducer cable should never be folded; rather, it should be loosely coiled to prevent breaking the cable wires.
- The manufacturer specifies which cleaning agents are safe to use on the transducer. These instructions should be followed to prevent damage to the surface of the transducer. Abrasive cleaning agents and pads should never be used to clean transducer heads.
machine should be kept covered when not in use |
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Term
| How does cold weather affect ultrasound examinations? |
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Definition
- Cold weather can affect ultrasound examinations by altering the properties of coupling gels and standoff pads.
- If possible, examinations should not be performed in extreme cold.
- When performing examinations in a cold environment, the coupling gel should be applied and allowed to warm to the patient's skin temperature before conducting the examination.
- Standoff pads also benefit from warming before use; placing the pad against the body for several minutes can warm the pad in a cold environment if another heat source is not available |
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