Diagnostic ultrasound ( PDFDrive )

718 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
A
B
FIG. 19.36 Biopsy of Recurrent Papillary Carcinoma in Thyroid Bed After Thyroidectomy. (A) Transverse scan of right side of the neck
shows a 1-cm solid mass (arrows) medial to carotid artery (C) and jugular vein (J). (B) Sonographically guided ine-needle aspiration with needle
seen within mass (arrow).
A
B
FIG. 19.37 Normal Cervical Lymph Nodes: Elongated Shape Is Typical. Longitudinal images. (A) Slender node (calipers) is homogeneous
except for central echogenic hilum. (B) Normal homogeneous slender node (calipers) near the jugular vein without a visible hilum.
a slender, oval shape and oten exhibit a central echogenic band
that represents the fatty hilum (Fig. 19.37). Malignant lymph
nodes, on the other hand, are more oten located in the lower
third of the neck and are usually rounder and have no echogenic
hilum, presumably because of obliteration by tumor iniltration
(see Fig. 19.17). Although oten hypoechoic, malignant nodes
may be difusely echogenic, may be heterogeneous, and may
contain calciications and cystic changes. Calciications can be
seen in nodal metastases from papillary and medullary thyroid
malignancies, and cystic changes are very characteristic in
metastatic papillary carcinoma. 102 In addition, Lyshchik and
colleagues 103 reported that with use of elastography, cervical
lymph nodes with a strain index greater than 1.5 are usually
malignant (85% sensitivity and 98% speciicity).
When the diferentiation between benign and malignant lymph
nodes is not feasible with sonography, FNA under sonographic
guidance is oten used. In our experience, biopsy can be done
with a high degree of accuracy in cervical nodes that are as small
as 0.5 cm in diameter. 58 In addition to cytologic analysis, the
“wash-out” of the aspirate can be sent for thyroglobulin assay,
which is highly accurate for the diagnosis of metastatic papillary
and follicular cancer. 104