Ultrasonic examination method of B-ultrasound machine for large animals

Ultrasonography of animals is the second most commonly used imaging format in veterinary practice. It uses ultrasound waves in the 1.5-15 megahertz (MHz) frequency range to create images of animal structures based on echo patterns reflected from the tissues and organs to be imaged.

Several types of image formats can be displayed. B-mode grayscale scanning is one that creates images of actual anatomy. The sound beam is generated by a transducer that is in contact with the transmission gel and coupled to the animal through acoustic transmission. Ultrashort pulses of sound are introduced into the animal, and the transducer switches to receive mode. Echoes occur as the beam velocity changes when the beam is shifted from one density of tissue to another, even though this change occurs on an almost microscopic level. The greater the speed change, the greater the echo intensity. A small portion of these echoes is reflected back to the transducer, which then converts the echo’s energy into electrical impulses that are recorded by a computer in the ultrasound machine. The strength of the echo, the time it takes for the echo after the pulse, and the direction of the sound beam sent are all recorded. The machine uses information from multiple echoes to create an image that represents what the tissue would look like when cut in the same plane on the dissected specimen.

In modern scanning systems, a sound beam is swept across the animal many times per second, creating a dynamic live image that changes as the transducer moves over the animal. This live image is easier to interpret and allows the examiner to continue scanning until a satisfactory image is obtained. The image can then be frozen and recorded in digital format, which also allows short clips of real-time scans to be recorded.
Animal B-ultrasound ultrasonography cannot be used to scan air-filled or bony tissue. The sound beam is totally reflected at the soft tissue/gas interface and absorbed at the soft tissue/bone interface. Gas and bone also “cover” any other organs besides them. Bowel gas can inhibit imaging of adjacent abdominal organs, so the heart must be imaged from locations that do not require the beam to pass through the lungs.

Ultrasound imaging in animals is also limited in the depth of tissue that can be examined. Most scanners will show tissue at a depth of ~24 cm, but images at that depth are often very noisy. This is because most tissue echoes do not return directly to the transducer, but reflect in other directions. A loss of beam energy of up to 24 cm causes echoes, so the scanner cannot distinguish returning echoes from background electronic noise. Additionally, some echoes that are not directly reflected may return to the transducer by reflecting off tissue outside the optical path. Such echoes take longer to return to the transducer and are depicted in spurious locations, adding noise to the image. Low frequency transducers scan deeper than high frequency transducers, but with reduced resolution.

Although ultrasound can be used to evaluate most soft tissues, including muscles, tendons, and ligaments, the heart and abdominal organs still constitute the majority of examinations performed on small animals. When scanning the abdomen, abdominal structures should be systematically assessed. Each animal sonographer will develop his or her own system for a complete assessment of the abdomen. System assessment ensures that all structures are scanned. In the past, organs such as the adrenals and pancreas could only be seen if they were diseased and enlarged, but modern ultrasound machines, operated by experienced sonographers, produce images of high quality enough to image normal adrenals, pancreas, and lymph nodes, and even The same is true under normal circumstances. Big dog.

Ultrasonography in animals is also widely used to evaluate the soft tissues of the musculoskeletal system. In the device, ultrasound is used to detect and evaluate the presence of tears in the tendons and ligaments of the legs. Examination of joints and periarticular bony margins is also widely performed in both large and small animals and yields information that cannot be obtained from standard radiographic assessment. Of course, ultrasound cannot be used to assess the bone itself, so the two imaging methods are complementary. In small animals, soft-tissue injuries to ligaments, tendons, joint capsules, and articular cartilage of the shoulder and stigma joints are easily detected by an experienced examiner.

In most cases, organs, tissues, and structures change significantly in size and shape, but the echogenic pattern is evaluated based on comparison with other organs and tissues that the examiner has scanned in other animals. The person evaluating the scan must have a solid idea of ​​the normal echogenic pattern for each organ scanned by each transducer, based on experience and comparison to known normals. The echo pattern will vary from sensor to sensor due to variations in axial and cross-axis resolution and sensor design. The echogenicity of several tissues must be compared because the echogenicity of the parenchyma of any organ may increase or decrease.