Diagnostic ultrasound ( PDFDrive )

CHAPTER 19 The Thyroid Gland 699
A
B
C
D
FIG. 19.12 Contrast-Enhanced Sonography to Differentiate Benign From Malignant Fluid-Filled Thyroid Nodules With Internal Septations
or Solid Projections. (A) Conventional B-mode sonogram of right thyroid lobe demonstrates large, mixed solid and cystic nodule. C, Common
carotid artery; Tr, tracheal air shadow. (B) Contrast-enhanced sonogram. After administration of contrast material, the internal contents are no
longer visible because they lack enhancement, indicating that the contents were likely colloid and blood products. (C) Conventional B-mode
sonogram in longitudinal plane demonstrates a nodule (arrow) arising from the posterior wall. (D) Contrast-enhanced longitudinal sonogram shows
that the nodule remains visible, indicating enhancement after contrast enhancement. The lesion was a cystic papillary carcinoma.
lymph node metastases 26,28 (Fig. 19.14, Video 19.4 and Video
19.5). Similar to the pathologic features, sonographic characteristics
of papillary carcinoma usually are relatively distinctive
(Figs. 19.15 and 19.16):
• Hypoechogenicity (90% of cases), resulting from closely packed
cell content, with minimal colloid substance.
• Microcalciications, appearing as tiny, punctate hyperechoic
foci, either with or without acoustic shadows. In rare but
usually aggressive cases of papillary carcinomas of childhood,
microcalciications may be the only sonographic sign of the
neoplasm, even without evidence of a nodular lesion 3,20,29,30
(see Fig. 19.15B).
• Hypervascularity (90% of cases), with disorganized vascularity,
mostly in well-encapsulated forms 30 (see Fig. 19.16).
• Cervical lymph node metastases, which may contain tiny,
punctate echogenic foci caused by microcalciications (Fig.
19.17). hese are mainly located in the caudal half of the deep
jugular chain. Occasionally, metastatic nodes may be cystic
as a result of extensive degeneration (Fig. 19.17H).
Cystic nodal metastases show a thickened outer wall, internal
nodularity, and septations in most cases, although they may
appear purely cystic in younger patients. 26 Cystic lymph node
metastases in the neck occur almost exclusively in association
with PTC, but occasionally with nasopharyngeal carcinomas. 31
On power Doppler sonography, noncystic nodes oten show
difuse hypervascularity with tortuous vessels, arteriovenous (AV)
shunts, and high vascular resistance (resistive index [RI] > 0.8).
In some cases, however, these nodes may show only prominent
hilar vascularity, similar to that of reactive nodes, and low RIs. 30
Papillary carcinoma rarely displays extensive cystic change
(Fig. 19.18). In our review of the amount of cystic change found
in 360 thyroid carcinomas, a large amount of cystic change
occurred in less than 3% of cases. 32 he overwhelming majority