Management of Thyroid Nodules Detected at US: Society of Radiologists in Ultrasound Consensus Conference Statement Radiology 2005; 237: 794-800 Presented by Int. 楊為傑

Introduction Goal: To determine which thyroid nodule should undergo FNA. FNA and cytopathological examination of a thyroid nodule are usually required before surgery. This recommendation based on nodules size and US characteristics

Methods and Conference Director, codirector and 19 panelists, all whom have specialty experience in thyroid nodule evaluation and treatment. Radiologist, Pathologist, Endocrinologist, Surgeon. 14 articles were sent before the conference.

Thyroid nodules 4-8% of adults by means of palpation. 10-41% by US 50% by autopsy

Risk of malignancy Age: <20 or >60 PE: firmness of the nodule, rapid growth, fixation to nearby structure, vocal cord paralysis, enlarged regional lymph nodes. History of neck irradiation, positive family history

Incidence of cancer by FNA For patients with thyroid nodules selected for FNA: 9.2%-13%, In patient with multiple thyroid nodules: cancer rate per person was 10-13%. 2/3 was found in largest nodules. Incidentally found thyroid nodule: the cancer rate was the same as above.

Thyroid cancer About 25000 newly diagnosed cases and 1400 died per year in United States. Papillary thyroid cancer: 75-80%. Follicular(10-20%), medullary(3-5%), anaplastic(1-2%). Papillary thyroid carcinoma: 30 years survival rate95%

US features of Thyroid cancer A thyroid nodule was defined as a discrete lesion within the thyroid gland that is distinguished from parenchyma Gray-scale and Doppler US. Size, echogenicity, composition, calcifications, halo, irregular margins, internal blood flow

US findings Size doesn’t matter Several US features increased risk of thyroid cancer

US features The combination of factors improved the positive predictive rate. Solid nodule with microcalicification 31.6% of being malignancy Flow in central portion malignancy ↑

Cytopathology With a experienced cytologist, the accuracy rate was high Negative– Suspicious—Positive—Nondiagnostic For positive results: false positive <1% For suspicious results: 30-65% will be proven as cancer Nondiagnostic rate: 15-20%. Cancer rate: 5-9%

Discussion To assist physician to decide which nodule should undergo FNA. May change Flexibility To diagnose and to begin treatment as early as possible. Avoid unnecessary tests and surgery.

Several Questions Diagnosis of small cancer (<1 or 2cm) improve life expectancy? Benefits of removing papillary cancer <1cm outweigh the risk of more patient receive surgery? If FNA and surgery ↑cost/benefit?

Discussion This recommendation apply to nodule > 1cm. US features + size

Consensus Statement

Statement Not apply to all patient, such as history of increased risk or positive physical findings.

Explanations Measurements: should take the maximum diameter. Calcification: in solid nodule if calcification present 3 folds malignancy than non Represent calcified psamomma bodies. Too small to induce posterior shadowing Tiny echogenicities calcification

Explanations Composition: Solid or predominantly solid nodules have higher risk Cystic lesion have a very low likelihood.

Color Doppler Marked internal flow  risk ↑ Differentiate solid part: tissue or clot or debris, etc. US-guide FNA: directed toward region with visible flow.

Explanations Interval growth: If the nodules grew during the serial US studies FNA is appropriate even prior FNA was benign. No consensus on how to define substantial growth

Abnormal cervical lymph nodes The presence of abnormal lymph nodes override the US features criteria. Biopsy of the node and ipsilateral thyroid nodule. Higher risks: heterogenous echotexture, calcifications, cystic areas. Size is less reliable than above.

For future 1.How should substantial growth be defined? 2.Other US features that might be used to prove a nodule is benign? 3.Cost-effectiveness?

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