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Smooth contour meaning12/14/2023 ![]() ![]() As the transducer moves farther to the right, the angle of the inferior hepatic border becomes increasingly blunted ( Fig. With luck, the right kidney may also be seen. As you scan past the vena cava, the gallbladder can be identified as a “black” structure in the fasted patient. As you track across the abdomen, you will recognize the aorta and then the vena cava. Now return to the starting point and scan past it toward the right side. The image is now dominated by a chaotic pattern of highly contrasting light and dark areas with no discernible shape, caused by the gas and liquid contents of the stomach. Its roughly triangular outline becomes progressively smaller and finally disappears. You can do this by varying the pressure on the transducer as needed.Īs the transducer moves farther to the left, the cross section of the liver diminishes in size. Also, make sure that the inferior border of the liver stays at the right edge of the image. Now slide the transducer to the left, keeping it in a longitudinal plane while following the line of the costal arch as closely as possible. This should bring the sharp inferior hepatic border into view ( Fig. Press the caudal end of the transducer a bit more deeply into the abdominal wall than the cranial end, so that the scan is directed slightly upward. Place the transducer longitudinally on the upper abdomen, slightly to the right of the midline. This inferior border is easy to demonstrate with ultrasound. The liver tapers inferiorly to a more or less sharp-angled border. If there is intervening gas in the right colic flexure, have the patient take a deep breath to expand the abdomen. To define the inferior border of the liver in longitudinal sections, press the caudal end of the transducer a little more firmly into the abdominal wall than the cranial end.īy varying the pressure on the transducer, you can keep the inferior border of the liver at the right edge of the image. 3 illustrates the view of the liver that is acceptable for organ identification. Now ask the patient to take a deep breath, expanding the abdomen, and the liver will appear on the screen as a region of homogeneous echo texture. Mentally picture the liver lying beneath the ribs, and angle the scan upward. Start with the transducer placed transversely against the right costal arch, at the level where you would palpate the inferior border of the liver. One disadvantage of holding the breath is that it is followed by a period of hyperventilation, especially in older patients. Place the patient in the supine position and have him or her take a deep breath and hold it to expand the abdomen. To make the liver more accessible, have the patient raise the right arm above the head to draw the rib cage upward. Even so, he is unable to see the man sitting in one corner of the room. Moving from window to window, he views the center of the room several times and sees corners a total of five times. In this analogy, an observer is looking into a room through three windows. ![]() Figure 5 shows the result of contour lines.įigure 5.Fig. The result can be seen in the QGIS map canvas without closing the contour plugin window, therefore we can switch back to change a parameter if the result not looks as we want. Furthermore the color graduation for the contour lines can be changed by selecting a color ramp for the output contour lines.Ħ. In the next setting we can specify the precision and unit for the contour label. The output will be written to memory, so we need to export to it to a GIS file to keep it permanently.ĥ. Moreover the interval can be edited manually by double click the interval number.Ĥ. We can tweak the number if the interval is not correct. When we set the calculated number, the contour interval can be seen in the right list. Then the number of contour line will be: maximum elevation/contour interval. For example if we want to make a contour map in 100.000 scale, then the contour interval will be 1/2000 x 100.000 = 50 m. We can set any number, but I suggest the number of contour line follows the rule of thumb as mentioned above. Next, we have to define the number of contour lines. In the contouring menu, we can choose to create contour line, filled contour or both. Select the point's layer name and the elevation data field. The contour plugin window will appear as in figure 4.ģ. Open the Contour plugin by clicking the icon. ![]() Add the points into QGIS map canvas as in figure3.Ģ. Now, let's make contour lines from points dataset with the following steps:ġ. Check it and Install the plugin if you don't have it in your QGIS 3. You will see the Contour plugin appears as in figure 2. As usual we can get the plugin from Plugins menu > Manage and install plugins. To create contour lines from points, we are using Contour plugin. ![]()
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