Diagnostic ultrasound ( PDFDrive )

720 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
treatment can be targeted to achieve complete ablation. 112
Complete cure is deined as normalization of serum free thyroid
hormones and serum thyrotropin and scintigraphic reactivation
of extranodular tissue. Partial cure occurs when serum free
thyroid hormones and thyrotropin levels are normalized, but
the nodule is still visible on scintigraphy. 111,113
Percutaneous ethanol injection is generally well tolerated. he
common side efect is a brief burning sensation or moderate
pain at the injection site, radiating to the mandibular or retroauricular
regions. he slow withdrawal of the needle and use of
the multihole needle reduce this side efect. In some patients
with larger nodules, when the amount of necrosis is high, fever
lasting 2 to 3 days develops ater the initial treatments. he only
important complication is transient damage of the recurrent
laryngeal nerve, reported in 1% to 4% of cases. 80,94 Nerve damage
is induced chemically or by compression. Full nerve recovery is
likely because, in contrast to surgery, there is no anatomic nerve
interruption.
Eicacy of response is inversely proportional to the nodule
volume; the smaller the nodule, the more complete the response.
Complete cure is achieved in 68% to 100% of pretoxic nodules
and 50% to 89% of toxic nodules. 111-116 Ultrasound-guided
percutaneous ethanol injection is the treatment of choice in older
patients with contraindications to surgery, in pregnant patients,
and in patients with large autonomous nodules (>40 mL), in
addition to medical treatment to obtain euthyroidism more
rapidly.
More recently, the use of radiofrequency ablation (RFA)
with either internally cooled or multipronged electrodes has been
reported in the treatment of autonomously functioning thyroid
nodules, mostly for large nodules causing compressive symptoms.
A signiicant decrease in size (≥50%) of the treated lesions was
reported in all cases, and complete normalization of thyroid
function was achieved in 24% to 44% of patients. 117,118 Also laser
ablation has been used in the treatment of large toxic nodular
goiter and has been proposed as combined treatment with 131 I
to fasten the volumetric reduction and reduce the radioactive
dose administered to the patient. 119
Percutaneous Treatment of Solitary Solid Benign
“Cold” Thyroid Nodules. In patients with solitary solid,
biopsy-proven, benign “cold” thyroid nodules, ethanol injection,
interstitial laser photocoagulation, and RFA have been proposed
as ultrasound-guided percutaneous treatments, to achieve marked
shrinkage of the nodule to a small, ibrous-calciied mass. With
percutaneous ethanol injection, a mean nodule volume reduction
of 84% (range, 73%-98%) has been reported ater 3 to 10 treatments.
120 With low-power interstitial laser photocoagulation,
mean thyroid nodule volumes decreased by 40% to 50% ater 6
months, with improvement of local clinical symptoms in approximately
80% of patients and no side efects. 121-124
RFA with internally cooled electrodes and low power (20-70
W) has also been employed for the treatment of benign cold
thyroid nodules, with only one ablation session for a single
nodule. A signiicant volume reduction of the treated nodules
without adverse efects has been reported at follow-up, but
studies with longer follow-up are needed to assess eicacy and
safety. 125,126
Treatment of Cervical Nodal Metastases From Papillary
Carcinoma. RFA, laser ablation, and ethanol injection have
been proposed for the treatment of recurrent disease and metastatic
lymph nodes in patients who have previously undergone
surgery. Percutaneous ethanol injection is an efective and safe
method of treatment for limited lymph node metastasis from
thyroid cancer. In a 2002 report from the Mayo Clinic, 14 patients
who had undergone thyroidectomy for PTC had 29 metastatic
lymph nodes on follow-up sonographic imaging. 127 Each node
was treated with direct injection of ethanol using ultrasound
guidance. Follow-up examination at 2 years showed a 95%
decrease in the size of treated nodes. here were no major
complications (e.g., recurrent laryngeal nerve palsy, bleeding)
in the Mayo Clinic series or in 187 patients with papillary cancer
nodes treated with percutaneous ethanol injection at the Ito
Hospital in Japan. 128,129
he percutaneous ethanol injection technique is similar to
the method used for percutaneous ethanol therapy of parathyroid
adenomas. A 25-gauge needle is attached to a tuberculin syringe
containing up to 1 mL of 95% ethanol. he needle is placed with
ultrasound guidance using a freehand technique that allows ine
positioning of the needle within the node (Fig. 19.39). Each
node is injected in several sites. he portion of the node that is
injected becomes hyperechoic owing to the formation of microbubbles
of gas. Ater usually less than 1 minute, the hyperechoic
zone decreases. he needle is repositioned in the node, and several
injections are made until the node appears adequately treated.
Patients may experience mild to moderate pain at injection, but
this resolves within minutes. For small nodes about 5 mm in
diameter, a single injection may be suicient. For larger nodes,
a reinjection the following day is needed for complete therapy.
Follow-up ultrasound at 3 to 6 months will show a reduction in
size of the node in most cases. If blood low was visualized in
the node before therapy, it will oten be substantially decreased
or absent on follow-up. If on follow-up the size of the node has
not decreased, or if there is residual blood low on power Doppler
examination, a repeat injection is performed.
hermal ablation of nodal recurrent thyroid cancer has also
been tested, with both RFA and laser ablation. In particular,
laser ablation seems to be particularly promising in the treatment
of nodal metastases from thyroid carcinoma; it is performed
using thin (21-gauge) needles, and the energy can be delivered
with great precision, allowing avoidance of damage to critical
surrounding structures. 130-132
The Incidentally Detected Nodule
Although using high-frequency sonography to detect small,
nonpalpable thyroid nodules may be beneicial in certain clinical
settings, it may actually introduce problems in other situations.
What should one do with the many thyroid nodules detected
incidentally during carotid, parathyroid, and other sonographic
examinations of the neck? he goal should be to avoid extensive
and costly evaluations in the majority of patients with benign
disease, without missing the minority of patients who have
clinically signiicant thyroid cancer. In our literature review, the
incidence of thyroid nodules in patients can be estimated by
method of detection: autopsy (49%), sonography (47%), palpation