Diagnostic ultrasound ( PDFDrive )

CHAPTER 19 The Thyroid Gland 721
A
B
C
D
FIG. 19.39 Ethanol Treatment of Thyroid Metastasis in a Cervical Lymph Node. (A) Longitudinal color Doppler image shows a round,
1.6-cm, pathologic-appearing node with moderate vascularity. (B) The tip of a 25-gauge needle (arrow) is in the lymph node. (C) The ethanol effect
is visible as a focal hyperechoic area (arrow) at injection and is caused by microbubbles that form from the interaction of ethanol with the tissues.
This hyperechoic appearance will last from several seconds to several minutes and will be followed by a normal or near-normal appearance. During
the injection, the hyperechogenicity is a useful marker to identify the areas treated. (D) Follow-up power Doppler image 6 months after ethanol
injection shows that the lymph node has dramatically decreased in size (0.4 cm) and is no longer vascular. No further therapy is needed except to
follow every 6 to 12 months to conirm lack of change.
(7%), occult cancer at autopsy (2%), and annual cancer incidence
(0.005%).
Understanding the challenge of selecting nodules for workup
requires background information in the following four areas:
1. he epidemic of thyroid nodules has resulted mostly from
ultrasound imaging.
On physical palpation, an estimated 7% of the North American
population has at least one thyroid nodule. In contrast, there is
an “epidemic” of thyroid nodules detected by ultrasound, with
studies showing up to 67% of patients having a nodule. 133 Our
study of 1000 consecutive patients imaged with 10-MHz ultrasound
transducers showed a prevalence of 41%. 134 his study
also showed an increasing prevalence with advancing age, which
parallels autopsy rates of prevalence compared with patient age
(Fig. 19.40).
From these studies it is reasonable to estimate that more than
100 million Americans have thyroid nodules on ultrasound. he
problem of the high rate of incidentally detected thyroid nodules,
the so-called “incidentaloma,” has led some to ask if it is “time
to turn of the ultrasound machines.” 135 he morbidity and cost