Thyroid nodule diagnostic study of choice
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]
Overview
There is no definite diagnostic criteria for thyroid nodule. Different diagnostic methods can be used to diagnose thyroid nodules, based on their specific properties. Thyroid function should be assessed in all patients with thyroid nodules as the primary diagnostic step in all patients with a neck mass. The primary evaluation method that should be used in the thyroid nodule evaluation is thyroid ultrasound. Cytology differentiates between malignant and benign lesions. After a suspicion of thyroid malignancy based on ultrasound features, fine needle aspiration biopsy (FNAB) is the most appropriate method for further evaluation. Thyroid scintigraphy is used to determine the functional status of a nodule. Scintigraphy utilizes one of the radioisotopes of iodine (usually I-123) or technetium-99m pertechnetate.
Diagnostic Criteria
- There is no definite diagnostic criteria for thyroid nodule. Different diagnostic methods can be used to diagnose thyroid nodules, based on their specific properties.
- Thyroid function tests should be assessed in all patients with thyroid nodules as the primary diagnostic step in all patients with a neck mass.
- The primary evaluation method that should be used in the thyroid nodule evaluation is thyroid ultrasound. Thyroid ultrasound should be performed in all patients with a suspected thyroid nodule or nodular goiter on physical examination or with nodules incidentally noted on other imaging studies. Ultrasound diagnosis of malignant thyroid nodules if done based on marked hypoechogenicity, microcalcification and mixed central, peripheral or central doppler color flow pattern has sensitivity of 100 % and a specificity of 76 % were obtained in detecting malignant nodules using this criteria:[1]
- Ultrasound indication critera:
- Suspected thyroid nodule
- Nodular goiter
- Radiographic abnormality
- Nodule found incidentally on computed tomography (CT) or magnetic resonance imaging (MRI)
- Thyroidal uptake on 18FDG-PET scan
- Ultrasound indication critera:
- Subsequent evaluation is based upon the TSH level and sonographic features of the nodules.
- Cytology differentiates between benign and malignant lesions. Cytology is the primary determinant in thyroid nodule management. After a suspicion of thyroid malignancy based on ultrasound features, fine needle aspiration biopsy (FNAB) is the most appropriate method for further evaluation. Overall sensitivity and specificity of the FNAB technique have been reported to be 83% and 92% respectively.[2]
- Thyroid scintigraphy is used to determine the functional status of a nodule. Scintigraphy utilizes one of the radioisotopes of iodine (usually I-123) or technetium-99m pertechnetate. If available, radioiodine scanning is preferred. Studies suggest that with an uptake threshold of 15.2%, sensitivity and specificity of thyroid scinitigraphy are 82.4% and 69.0% respectively.[3]
Diagnostic approach
The following approach is based on American Thyroid Association (ATA) guidelines for assessment of thyroid nodules, the latest version was released in 2015.[4]
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Abbreviations:
TSH: Thyroid stimulating hormone, FNA: Fine needle aspiration, FLUS: Follicular lesion of undetermined significance, AUS: Atypia of undetermined significance.
References
- ↑ Lingam RK, Qarib MH, Tolley NS (2013). "Evaluating thyroid nodules: predicting and selecting malignant nodules for fine-needle aspiration (FNA) cytology". Insights Imaging. 4 (5): 617–24. doi:10.1007/s13244-013-0256-6. PMC 3781256. PMID 23712566.
- ↑ Maia FF, Zantut-Wittmann DE (2012). "Thyroid nodule management: clinical, ultrasound and cytopathological parameters for predicting malignancy". Clinics (Sao Paulo). 67 (8): 945–54. PMC 3416902. PMID 22948464.
- ↑ Hou H, Hu S, Fan R, Sun W, Zhang X, Tian M (2015). "Prognostic value of (99m)Tc-pertechnetate thyroid scintigraphy in radioiodine therapy in a cohort of Chinese Graves' disease patients: a pilot clinical study". Biomed Res Int. 2015: 974689. doi:10.1155/2015/974689. PMC 4387899. PMID 25879041.
- ↑ "ATA Professional Guidelines | American Thyroid Association".