Diagnostic ultrasound ( PDFDrive )

710 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
A
B
FIG. 19.28 Thyroid Metastasis From Renal Cell Carcinoma. (A) Longitudinal (gray-scale) and (B) power Doppler images show a 1-cm solid
vascular mass.
TABLE 19.1 Diagnostic Yield of Thyroid Fine-Needle Aspiration (FNA)
Series No. of Cases FN rate FP rate Sensitivity Speciicity
Hawkins et al. 44 1399 2.4% 4.6% 86% 95%
Khafagi et al. 45 618 4.1% 7.7% 87% 72%
Hall et al. 46 795 1.3% 3.0% 84% 90%
Altavilla et al. 47 2433 6.0% 0.0% 71% 100%
Gharib and Goellner 43 10,971 2.0% 0.7% 98% 99%
Ravetto et al. 48 2014 11.2% 0.7% 89% 99%
FN, False-negative; FP, false-positive.
Modiied from Gharib H, Goellner JR. Fine-needle aspiration biopsy of the thyroid: an appraisal. Ann Intern Med. 1993;118(4):282-289. 43
3. Suggestive of malignancy
4. Nondiagnostic
If a nodule is classiied in either of the irst two categories,
the results are highly sensitive and speciic. 42 he major limitation
of the technique is the lack of speciicity in the third group—results
are suggestive of malignancy—primarily because of the inability
to distinguish follicular or Hürthle cell adenomas from their
malignant counterparts. In these cases, surgical excision is
required for diagnosis. In addition, up to 20% of aspirates may
be nondiagnostic, approximately half of which result from
inadequate cell sampling of cystic lesions. In these cases, repeat
FNA under sonographic guidance can be performed for selective
sampling of the solid elements of the mass. In the world literature,
FNA of thyroid nodules has a sensitivity range of 65% to 98%
and speciicity of 72% to 100%, with a false-negative rate of 1%
to 11% and a false-positive rate of 1% to 8% 43-49 (Table 19.1). In
a study based on more than 5000 cytologic examinations, the
most frequent cause of false-negative indings was the failure to
recognize the follicular variant of papillary carcinoma. 49 In our
practices, the overall accuracy of FNA exceeds 95%, and therefore
it is currently the most accurate and cost-efective method for
initial evaluation of patients with nodular thyroid disease. Since
the introduction of FNA into routine clinical practice, the percentage
of patients undergoing thyroidectomy has substantially
decreased (to ~25%), and the cost of thyroid nodule care has
been reduced by 25%. 43
he evaluation of thyroid nodules primarily by FNA is common
in North America and northern Europe. In other European
countries and Japan, where goiter is prevalent, the initial evaluation
oten relies on radionuclide and sonographic imaging
because of the need to select nodules that must undergo FNA.
Sonographic Applications
Although FNA is the most reliable diagnostic method for evaluating
clinically palpable thyroid nodules, high-resolution sonography
has four primary clinical applications 50-52 :
• Detection of thyroid and other cervical masses before and
ater thyroidectomy
• Diferentiation of benign from malignant masses on the basis
of their sonographic appearance
• Guidance for FNA biopsy
• Guidance for the percutaneous treatment of nonfunctional
and hyperfunctioning benign thyroid nodules and of lymph
node metastases from papillary carcinoma
Detection of Thyroid Masses
A practical use of sonography is to establish the precise anatomic
location of a palpable cervical mass. he determination of whether