Diagnostic ultrasound ( PDFDrive )

1724 PART V Pediatric Sonography
A
B
C
D
FIG. 50.35 Macrocystic Lymphatic Malformation in 7-Month-Old Girl. (A) Chest radiograph shows opacity in left upper chest and neck.
(B) and (C) Sonograms show multiple cystic spaces. (D) T1-weighted postcontrast, axial magnetic resonance image deines the extent of the
lesion.
TABLE 50.1 Formula for Calculation of Thymic Index
Thymic index (cm 3 ) = Area of the largest lobe (cm 2 ) × Transverse dimension of thymus from right lateral
edge to left lateral edge (cm)
Area of the lobe of
thymus (cm 2 )
= Craniocaudad dimension (cm) × Anteroposterior dimension (cm)
malformation, or Langerhans cell histiocytosis. Malignant iniltration
of the thymus is also seen in lymphoma and leukemia.
hymic cysts are anechoic. Other abnormalities of the thymus
may show irregular or lobular margin, heterogeneous echogenicity,
and coarse echotexture. Germ cell tumors can have variable
appearance. Teratomas are heterogeneous masses that contain
fat, bone, calciication, and cystic elements.
Lymphadenopathy
he most common mediastinal mass in older children is lymphadenopathy
resulting from leukemia or lymphoma. Lymphadenopathy
appears as hypoechoic nodules. Lymph nodes in
lymphoma are more hypoechoic and more hypovascular than
inlammatory lymph nodes. 62
Posterior Mediastinal Masses
Posterior mediastinal masses, including neurogenic tumors, make
up the majority of mediastinal masses in young infants. Neurogenic
tumors appear as a lobulated or well-deined hypoechoic
mass with granular or lecklike calciications. Neurenteric cysts
are well-deined, anechoic lesions with thin walls. When inlammation
and hemorrhage occur, the cyst may contain echogenic
debris from proteinaceous luid, mucus, or blood.
ULTRASOUND-GUIDED
INTERVENTIONAL PROCEDURES
Sonography is an excellent method for guiding postoperative
luid collections 63 (Fig. 50.37), pleural luid aspiration, 64