Diagnostic ultrasound ( PDFDrive )

CHAPTER 50 The Pediatric Chest 1725
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FIG. 50.36 Thymic Index Measurement in Healthy
31-Month-Old Boy. (A) Transverse sonogram shows
measurement of transverse dimension of the thymus
from right lateral edge to the left lateral edge. (B) and
(C) Longitudinal images of right lobe and left lobe of
thymus, respectively. Area of each lobe is measured
by multiplying the craniocaudad and anteroposterior
dimensions. Images were obtained during expiratory
phase. Area of the right lobe (5.9 cm 2 ) is larger than
the left lobe (3.5 cm 2 ). Thymic index (19.5 cm 3 ) is the
product of area of the larger lobe (5.9 cm 2 ) and transverse
dimension (3.3 cm) of the thymus.
mediastinal mass biopsy, and chest wall lesion biopsy. Ultrasound
can be used either for marking the skin overlying a luid collection
or for directly visualizing a needle during insertion into a collection
(Fig. 50.37). Ultrasound is particularly helpful in determining
whether the pleural efusion will respond to simple drainage
or will require surgical decortication. 65 If the luid is relatively
anechoic or clear, simple drainage with thoracentesis or chest
tube drainage is an adequate treatment. If the luid is thick with
multiple septations, and if the patient does not respond promptly
to antibiotic therapy, decortication or video-assisted thoracic
surgery may be required. 11,66 Complicated parapneumonic efusions
and empyemas have been successfully treated in up to 93%
of children, using tissue plasminogen activator administered
through a small-bore chest tube. 67
Empyema surrounded by lung may appear to be a pulmonary
abscess on sonography. Changing the patient position and the
viewing planes can help distinguish an empyema from a lung
abscess (Fig. 50.38). Ultrasound can be used to guide needle
aspiration for etiologic diagnosis in patients with complicated
pneumonia, as well as aspiration of microabscesses in necrotizing
pneumonia.
Sonography can detect pneumothoraces 68 ater thoracentesis. 69
Before and ater thoracentesis, the ipsilateral pulmonary apex
and adjacent lung should be examined in the upright position