Diagnostic ultrasound ( PDFDrive )

1222 PART IV Obstetric and Fetal Sonography
A
L
L
L
L
C
B C D
C
FIG. 35.7 Posterior Transaxial Scan Plane. (A) Diagram shows the incident sound beam (arrows) relecting off the posterior surfaces, clearly
demonstrating the laminae and centrum but not the pedicles. The red structures represent the ossiied portions of the vertebra. (B) The L3
vertebra at 17 weeks’ gestation demonstrates the ossiied laminae (L) and the ossiied centrum (bottom arrow) but not the pedicles. (C) Scan of
S1 vertebra at 17 weeks shows early ossiication at the lamina-pedicle junction on each side (long thin arrows). With this amount of ossiication,
determining the course of the laminae is not possible, and thus excluding spina biida is dificult. C, Ossiied centrum; short arrows, iliac wing. (D)
Scan of T10 at 24 weeks’ gestation shows advanced ossiication in the laminae (L, arrows) almost reaching midline. Despite their advanced ossiication,
the pedicles are not visualized in this scan plane. C, Ossiied centrum.
P
C
P
A
B
FIG. 35.8 Lateral Transaxial (Transverse) Scan Plane. (A) Diagram shows the incident sound beam (arrows) relecting off the lateral surfaces
of the centrum and the near pedicle and off the medial surface of the far pedicle, demonstrating the centrum and pedicles, but not the laminae.
The laminae course toward midline (thus sound beam is not perpendicular to laminar surface) and caudally (thus out of the plane of sound beam).
The red structures are ossiied portions of the vertebra. (B) Scan of vertebra L3 at 17 weeks’ gestation shows the ossiied pedicles (P) and the
ossiied centrum (C) but not the laminae.