Diagnostic ultrasound ( PDFDrive )

CHAPTER 40 The Fetal Musculoskeletal System 1385
A B C
D
E
F
G H I
FIG. 40.9 Collage of Three-Dimensional Images. (A) Normal skull at 22 weeks, frontal aspect. (B) Femur and iliac bone at 22 weeks. (C)
Upper extremity at 22 weeks. (D) Normal skull at 22 weeks, superior aspect. (E) Face and skull at 22 weeks. (F) Normal lower limb at 22 weeks,
proile. (G) Wormian bones, posterior fontanelle. (H) Hemivertebrae at 23 weeks. (I) Osteogenesis imperfecta; note abnormally shortened,
curved, and thickened femurs. (Courtesy of Dr. Bernard Benoit.)
and may provide a valuable complementary diagnostic tool in
the appropriate clinical situation. 43,47 It is important to take into
consideration the fetal radiation dose, which has been estimated
to be in the 3-mGy range. However, new dose reduction techniques
such as iterative reconstruction are estimated to reduce
the dose by as much as 80%. Postmortem three-dimensional CT
scan 48 may provide a “virtual autopsy,” particularly when autopsy
has been declined.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) plays a relatively limited
role in the assessment of the fetal skeletal dysplasia. However,
in cases with inconclusive ultrasound indings and for cases in
which MRI is expected to provide important additional
information, MRI may be useful. 49 MRI can also be helpful in
the context of “virtual autopsy” for families who have declined
autopsy. 50
Molecular Diagnosis
Molecular conirmation of suspected skeletal dysplasia during
pregnancy has traditionally been of limited usefulness because
of the length of time needed to obtain a result, especially if the
diferential diagnosis required sequencing of several genes. he
advent of next-generation sequencing technologies is now enabling
the simultaneous examination of multiple genes in a reasonable
time frame. It should be noted, however, that negative molecular
testing does not exclude the diagnosis of a skeletal dysplasia and
the prognosis must be based on the imaging indings.