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Atlas of Human Body Ultrasound Scanning_ Methods and Diagnostic Applications ( PDFDrive ).pdf
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9  Abdominal Vascular Scanning

365

 

 

8.2\ Long-Axis View of the

Superior Mesenteric Vein

LL

SMV

PN

HA

Fig. 9.30  Long-axis view of the superior mesenteric vein

8.2.1\ Scanning Method

The patient should be fasted for more than 8 h, and should be in a supine position. The probe is

placed transversely under the xyphoid process and moved downward after the pancreas is shown on the image. The probe is rotated after the transverse section of the SMV or the configuration part of SMV and the splenic vein is shown. Some pressure should be exerted in obese patients.

8.2.2\ Section Structure

Longitudinal section of the SMV, the neck of the pancreas; transverse section of the hepatic artery.

8.2.3\ Measurement Method and Normal Value

The SMV is a tapering anechoic band on the image. The anterior–posterior diameter is usually less than 0.9 cm. The filling and direction of the blood flow can also be evaluated. The spectrum is a single-phase continuous flow centripetal to the liver, just like the spectrum of the portal vein.

8.2.4\ Clinical Application Value

In the case of portal hypertension, the direction of the flow may be centrifugal to the liver. In the case of SMV thrombosis, the diameter of the lumen increases and the vessel cannot be compressed. The distal segment of the SMV may show little blood flow signal because of a large echo–flow angle; in this case, adjusting the angle of the probe is necessary to avoid misdiagnosis of thrombosis.