Diagnostic ultrasound ( PDFDrive )

CHAPTER 19 The Thyroid Gland 719
A
B
FIG. 19.38 Ethanol Treatment of Large Colloid Cyst. (A) Transverse image shows large colloid cyst with needle. Injected ethanol appears
as low-level echoes (E). Tr, Tracheal air shadow. (B) Follow-up image 1 month later shows that the large cystic component has mostly resolved,
leaving a slightly enlarged residual gland (arrows).
Guidance for Percutaneous Treatment
Ethanol Injection of Benign Cystic Thyroid Lesions.
Lesions containing luid (usually colloid cysts) account for 31%
of thyroid nodules found on sonography, but less than 1% of
these are pure epithelial-lined cysts. 5 Management of cystic thyroid
nodules relies irst on FNA biopsy to rule out malignancy. Simple
aspiration may result in permanent shrinkage of the lesion, but
the recurrence rate ater aspiration is high, 10% to 80%, depending
on the number of aspirations and the cyst volume; the greater
the volume, the greater the recurrence risk. 105,106
Prevention of cyst recurrence requires intranodular injection
of a sclerosing agent. Ethanol has been used successfully for the
past 20 years, with accurate placement using real-time sonographic
guidance. Ethanol is distributed within tissues by difusion and
induces cellular dehydration and protein denaturation, followed
by coagulation necrosis and reactive ibrosis. he cyst luid is
completely aspirated with a ine needle, and then sterile 95%
ethanol is injected under ultrasound guidance, in an amount
varying from 30% to 60% of the aspirated luid 107,108 (Fig. 19.38).
Subsequently, ethanol can be either reaspirated in 1 to 2 days or
permanently let in place. In large cystic cavities, this procedure
can be repeated once or twice ater several weeks. he volume
reduction of the cyst is more substantial if a larger amount of
ethanol is injected; thus a relationship exists between the volume
of ethanol instilled and the ablative efect.
Ethanol injection is usually well tolerated by the patient.
Transient mild to moderate local pain is the most common
complication, a result of ethanol leaking into subcutaneous tissue.
Rare complications of ethanol sclerotherapy are transient
hyperthyroidism, hoarseness, hematoma, and dyspnea.
Reported success rates (total disappearance or volume reduction
greater than 70% of initial volume) of this treatment range
from 72% to 95% at long-term follow-up, 107-110 achieved without
a change in thyroid function. Ethanol injection is considered
the percutaneous treatment of choice for cystic lesions of the
thyroid gland at some institutions.
Ethanol Injection of Autonomously Functioning Thyroid
Nodules. hyroid nodules with independent secretory and
proliferative activity are deined as autonomous thyroid nodules.
On radionuclide scans, these nodules appear “hot,” in contrast
to the low or absent extranodular uptake, likely related to the
avidity of iodine trapping and the degree of thyroid hyperfunction.
he patient’s condition may be toxic or nontoxic, depending
on the amount of thyroid hormones secreted. he level of
hyperthyroidism is usually proportional to the nodule volume.
herefore autonomous thyroid nodules can cause a range of
functional abnormalities, from euthyroidism (compensated) to
subclinical hyperthyroidism (pretoxic) and clinical hyperthyroidism
(toxic).
he currently available treatments of autonomous nodules
include surgery and radioactive iodine therapy. Surgery is efective
but has the disadvantage of anesthesiology and surgical risks.
Radioactive iodine therapy may require repeated sessions before
achieving euthyroidism.
Percutaneous ethanol injection under ultrasound guidance,
irst proposed by Livraghi and colleagues 111 in 1990, is an alternative
therapy. he difusion of ethanol causes direct damage. Cell
dehydration is followed by immediate coagulation necrosis and
subsequent ibrotic changes. Sterile 95% ethanol is injected
through a 21- or 22-gauge spinal needle with closed conical tip
and three terminal side holes. his allows the injection of a large
amount of ethanol, reduces the total number of sessions, increases
the treated volume, and minimizes the risk of laryngeal nerve
damage because of the lateral difusion of ethanol. Several treatment
sessions are needed (usually four to eight), typically performed
at 2-day to 2-week intervals. he total amount of ethanol
delivered is usually 1.5 times the nodular volume.
Color Doppler imaging and, if available, contrast-enhanced
sonography are extremely valuable to assess the results of ethanol
injection. he reduction (up to complete disappearance) of
vascularity and contrast enhancement is directly related to the
ethanol-induced necrosis. In addition, residual vascularity ater