The Thyroid: Review of Imaging Features and Biopsy Techniques with Radiologic-Pathologic Correlation

Abstract

Knowledge of the normal and abnormal imaging appearances of the thyroid gland is essential for appropriate identification and diagnosis of thyroid lesions. Thyroid nodules are often detected incidentally at computed tomography, magnetic resonance imaging, and positron emission tomography; however, ultrasonography (US) is the most commonly used imaging modality for characterization of these nodules. US characteristics that increase the likelihood of malignancy in a thyroid nodule include microcalcifications, solid composition, and central vascularity. Nuclear scintigraphy is commonly used for evaluation of physiologic thyroid function and for identification of metabolically active and inactive nodules. When fine-needle aspiration biopsy (FNAB) of a lesion is indicated based on clinical and radiologic features, appropriate US-guided biopsy technique and careful cytologic analysis are crucial for making the diagnosis. FNAB and core biopsy are the two percutaneous techniques used to obtain a specimen, with the latter technique being indicated following nondiagnostic or indeterminate FNAB. Specimen adequacy and diagnostic accuracy vary due to several factors, including location of aspiration and biopsy technique used. The radiologist must have a basic knowledge of thyroid disease, be familiar with specimen processing, and recognize the cytologic and radiologic appearances of thyroid lesions, all of which will facilitate the management of these lesions. Online supplemental material is available for this article.

Electronic Synoptic Reporting of Thyroid Nodules: Potential for Reduction in Number of Patients Undergoing Thyroid Nodule Biopsies

“…Palpable thyroid nodules occur at a rate of 5% in the general population [1] while thyroid sonography depicts nodules in up to 67% of the population [2]. The recent rise in cross-sectional imaging use especially CT and sonography has resulted in discovery of an increased number of asymptomatic thyroid nodules [3] with 5% -15% of these incidentally discovered thyroid nodules being malignant [1].…”

“…The recent rise in cross-sectional imaging use especially CT and sonography has resulted in discovery of an increased number of asymptomatic thyroid nodules [3] with 5% -15% of these incidentally discovered thyroid nodules being malignant [1]. These numerous suspicious nodules have heightened demand for further investigations including biopsy and surgery to exclude malignancy, increased overall costs for the healthcare system and stimulated the search for better ways to reduce unnecessary biopsies and ensure that only appropriate cases go on to further biopsy or surgery.…”

High resolution ultra sound and color Doppler in evaluation of thyroid nodule with fine needle aspiration cytology correlation

“…US characteristics that increase the likelihood of malignancy in a thyroid nodule include microcalcifications, solid composition, and central vascularity. 3 The detection of thyroid nodules has become more common with the widespread use of ultrasonography (US). 4 Thyroid gland is one of the most vascular organ of the body so Doppler examination provide useful diagnostic information.…”

“…1 The thyroid gland is uniformly hyperechoic on ultrasound in comparison to strap muscles and is seen best with the use of high resolution linear array transducer having frequency 7-10 MHz, and having color flow capability and low flow sensitivity. 2,3 The superior resolution of ultrasound images has resulted in discovery of a large number of thyroid nodules that heretofore had been obscured Use of color flow imaging identifies multiple small vessels within and adjacent to thyroid. [4][5][6] Normal thyroid gland is made up of two lobes located along either side of trachea and connected across the midline by isthmus.…”

Ultrasound Guided Fine-Needle Aspiration Biopsy of Thyroid Nodules: Does Radiologist Assistance Decrease the Rate of Unsatisfactory Biopsies?

“…The diagnostic accuracy of UG-FNAB and the adequacy of obtained specimens differ from each other due to various factors. One of the most important is the state of the nodule's area which is undergoing biopsy [11]. Therefore, some authors emphasize the role of a radiologist in the UG-FNAB procedure [6].…”