Ultrasound of thyroid cancer

Medical management of persistent or recurrent differentiated thyroid carcinoma

This article presents an overview of medical management of persistent or recurrent differentiated thyroid cancer, in particular focusing on monitoring strategy and treatment plans. Most patients with differentiated thyroid carcinoma can be successfully rendered to be free of disease with initial treatments, and those with persistent or recurrent disease can still expect long-term survival when they are monitored properly and treated accordingly. Along with serum thyroglobulin, neck ultrasonography, and radioactive iodine whole-body scans, the use of cross-sectional imaging studies and (18F) fluoro-2-deoxy-D-glucose-positron emission tomography have facilitated the effort in localizing lesions and traditional treatments can be implemented effectively. For disease resistant to conventional therapies, there are new treatment modalities emerging and being tested, including several agents targeting specific signaling pathways, each of which may offer the potential remedy.

US-elastography in the differential diagnosis of benign and malignant thyroid nodules

BACKGROUND

Ultrasound (US)-elastography is a newly developed imaging technique for the reconstruction of tissue stiffness by measuring the degree of tissue's deformation in response to the application of an external force. This technique has previously been shown to be useful in the differential diagnosis between benign and malignant tumors.

METHODS

The objective of this study was to assess the diagnostic accuracy of US-elastography in the differential diagnosis of thyroid cancer, using the cytologic/histopathologic analysis as the reference standard. A total of 67 consecutive patients with thyroid nodules who were referred to the Thyroid Unit at the Policlinico MultiMedica were enrolled in this prospective study between January and December 2006. Eighty-six nodules in these patients were examined by US B-mode, US color-power-Doppler, and US-elastography. Nodules were subjected to fine-needle aspiration biopsy and patients with a reading of malignant or indeterminate had thyroid surgery. The final diagnosis was based on the cytology reading in those who did not have surgery and the histopathology reading in those who had surgery. US-elastography scores were based on four classes of tissue stiffness (class 1 for soft nodules; class 2 and 3 for nodules with an intermediate degree of stiffness; class 4 for anelastic lesions).

RESULTS

Seventeen nodules were malignant and 69 were benign. Sensitivity and specificity of the US-elastography for thyroid cancer diagnosis were 94.1% (16/17) and 81% (56/69), respectively. The positive and negative predictive values were 55.2% (16/29) and 98.2% (56/57), respectively. The accuracy of the technique was 83.7%.

CONCLUSION

US-elastography is a promising technique that, combined with other US modalities, is easy and rapid to perform and can help to identify thyroid nodules that are likely to be malignant. An important limitation is probably lack of sensitivity for follicular thyroid carcinoma.

Imaging for staging and management of thyroid cancer

The management of thyroid cancer has been controversial and, as a result, the routine use of imaging in this disease, especially for pre-operative staging, has lagged behind other head and neck cancers. However, as more is known about the natural history of thyroid cancer, the role of imaging is becoming more established. This review focuses on how imaging now influences the staging and management of the primary cancer, nodal metastases and distant metastases. This is followed by a brief review of the role of imaging in planning post-operative radiotherapy and post-treatment surveillance.

Papillary thyroid cancer: monitoring and therapy

The last 10 years have seen a major paradigm shift in the management of thyroid cancer, with greater reliance on serum thyroglobulin and neck ultrasonography, and less emphasis on routine diagnostic whole-body radioactive iodine scanning for detection of recurrent disease. As our follow-up tests become more sensitive for detection of recurrent disease, we are finding many asymptomatic patients who have low-level persistent disease many years after initial therapy that may or may not benefit from additional testing and therapy. These difficult issues have been addressed by at least five different sets of guidelines published recently by various thyroid specialty organizations around the world. In this article, the authors compare and contrast the recommendations from the various guidelines in an attempt to define areas of consensus and explore possible reasons for differing recommendations.

Magnetic resonance imaging of thyroid cancer

Thyroid cancer is a unique malignancy arising from the endocrine system, and its nature is different from more common squamous cell carcinoma in the head and neck region. Multiple imaging modalities are used for imaging work up for thyroid cancer, including nuclear medicine imaging, ultrasound, computed tomography, and magnetic resonance imaging (MRI). Imaging findings of benign and malignant thyroid lesions overlap substantially, and differentiation may be difficult. The role of MRI is to evaluate the extent of disease and to assess the spread of nodal disease. In this chapter, we will discuss the role of MRI in thyroid cancer staging and key imaging appearance that affect staging of thyroid cancer.