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Atlas of Human Body Ultrasound Scanning_ Methods and Diagnostic Applications ( PDFDrive ).pdf
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13  Normal Pregnancy

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4.31.2\ Section Structures

Femur looks similar to humerus in image (Fig. 13.43); its panorama can be shown in the sagittal section (i.e., long axis section), together with the soft tissues around it and the skin on the surface. In sagittal section, the femur or humerus in the middle is shown as a long or rodlike hyperechoic structure, while the soft tissues around it are shown as weak echoic region. In transverse or cross section, the femur or humerus is shown as a hyperechoic facula (i.e., cross section of the long bone) in the center of the section, with weak echoic soft tissues around it. Cross sections of the ulna and radius of the forearm are shown as two hyperechoic faculae in the transverse section, as well as cross sections of the tibia and fibula of shank. Two hyperechoic long bones are shown in the coronary section of the forearm or shank (Fig. 13.44).

4.31.3\ Measuring Method

The whole length of the diaphysis should be measured when measuring a long bone. The calipers should be placed on the midpoint of the cross section at the end of the diaphysis, not including the epiphysis on both ends.

4.31.4\ Clinical Significance

Length of the fetal long bone is a major index reflecting fetal growth and development and is also one of the important parameters of genetic ultrasound.

Placenta

The placenta is composed of the amnion, parenchyma, and chorionic plate; its echogenicity and internal light spots change with the gestational age.