Читать книгу Point-of-Care Ultrasound Techniques for the Small Animal Practitioner - Группа авторов - Страница 122

Every machine has a centimeter (cm) scale (Figure 5.13). Be familiar with where the maximum depth is on the screen, and how the marks are set up – as one hash mark every centimeter or are the hash marks every 5 mm or even every 2.5 mm? This will help you to locate the area of interest; for example, starting the FAST DH (subxiphoid) view at a depth of 5 cm even in medium‐sized dogs is too superficial (shallow or magnified) and won't properly image the diaphragm and gallbladder. The wise sonographer knows to start with a depth between 9 and 13 cm, get a feel for the four DH targets – diaphragm, gallbladder, cardiac bump, and caudal vena cava – and then magnify (decrease depth) once the targeted structures are identified from afar (see Chapters 6 and 7). On the other hand, lung is imaged at more shallow depths between 4 and 8 cm for smaller and larger patients, respectively.

Figure 5.13. Depth setting and the centimeter scale. The image is the same as Figure 5.12B with the focus cursor near center. The image has the centimeter scale to the right of the screen and then added numbers by the author for the depth of 12 cm. See how the hash marks correlate with 1 cm increments. Every ultrasound screen has a centimeter scale. Individual hash marks are often 1 cm (10 mm) on abdominal presets but can be every 0.5 cm (5 mm) or less. Find your cm scale and be aware of its depth scale. The screen itself has the depth (cm) and frequency (5 MHz), circled upper left and also at the screen's bottom along with number of focus cursors (1), plus other parameters noted (including the preset). Take the time to look over all the information provided on your machine's screen.

Source: Courtesy of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.