Diagnostic ultrasound ( PDFDrive )

CHAPTER 19 The Thyroid Gland 727
A
FIG. 19.49 Lymphoma in Hashimoto Thyroiditis. Transverse image
of the left lobe shows diffuse hypoechoic enlargement caused by
lymphoma in a gland with Hashimoto thyroiditis. Tr, Tracheal air shadow.
B
FIG. 19.51 Hyperthyroidism: Graves Disease. (A) Transverse
dual image of the thyroid gland shows marked diffuse enlargement of
both thyroid lobes and the isthmus. The gland is diffusely hypoechoic.
(B) Transverse color Doppler image of the left lobe shows increased
vascularity, indicating an acute stage of the Graves disease process. Tr,
Trachea.
FIG. 19.50 Hashimoto Thyroiditis With Hyperplastic Enlarged
Lymph Nodes. Longitudinal image shows micronodularity of Hashimoto
thyroiditis and an enlarged lymph node (arrow) inferior to the lower pole.
enlargement usually occurs in the early phase, in some cases
followed by hypothyroidism of variable degree. In postpartum
thyroiditis the progression to hypothyroidism is more common.
In most cases the disease spontaneously remits within 3 to 6
months, and the gland may return to a normal appearance.
Although the appearance of difuse parenchymal inhomogeneity
and micronodularity is typical of Hashimoto thyroiditis, other
difuse thyroid diseases, most frequently multinodular or adenomatous
goiter, may have a similar sonographic appearance. Most
patients with adenomatous goiter have multiple discrete nodules
separated by otherwise normal-appearing thyroid parenchyma
(see Fig. 19.29); others have enlargement with rounding of the
poles of the gland, difuse parenchymal inhomogeneity, and no
recognizable normal tissue. Adenomatous goiter afects women
three times more oten than men.
Graves disease is a common difuse abnormality of the thyroid
gland and is usually biochemically characterized by hyperfunction
(thyrotoxicosis). he echotexture may be more inhomogeneous
than in difuse goiter, mainly because of numerous large, intraparenchymal
vessels. Furthermore, especially in young patients,
the parenchyma may be difusely hypoechoic because of the
extensive lymphocytic iniltration or the predominantly cellular
content of the parenchyma, which becomes almost devoid of
colloid substance. Color Doppler sonography oten demonstrates
a hypervascular pattern referred to as the thyroid inferno (Fig.
19.51). Spectral Doppler will oten demonstrate peak systolic
velocities exceeding 70 cm/sec, which is the highest velocity
found in thyroid disease. here is no correlation between the
degree of thyroid hyperfunction assessed by laboratory studies
and the extent of hypervascularity or blood low velocities.
Previous studies have shown that Doppler analysis can be used
to monitor therapeutic response in patients with Graves disease. 152
A signiicant decrease in low velocities in the superior and inferior
thyroid arteries ater medical treatment has been reported.
he rarest type of inlammatory thyroid disease is invasive
ibrous thyroiditis, also called Riedel struma. 146 his disease
primarily afects women and oten progresses to complete
destruction of the gland. Some cases may be associated with