Original ArticleThe value of ultrasound elastography in differentiation of malignancy in thyroid nodules
Introduction
Thyroid gland nodules are common, and palpable nodules are found in between 4% and 7% of the adult population [1], [2]. Widespread use of ultrasound (US) imaging and development of high-resolution scanners have significantly improved the detection of thyroid nodules [2]. According to US imaging and autopsy results, the incidence of thyroid nodules may increase up to 50% of population [3], [4], [5]. The rate of malignancy among thyroid nodules range between 5% and 15% [6], [7]. US imaging is a definitive method for detection of thyroid nodules; however, the predictive value of US in differentiation of malignant nodules is limited [8], [9]. Currently, the best available method for discrimination of malignant from benign thyroid nodules is fine needle aspiration biopsy (FNAB) [10], [11], [12]. Despite its high sensitivity and specificity, FNAB is an invasive procedure and may give nondiagnostic results in 10% to 20% of biopsies [6].
Palpation is clinically used to evaluate the stiffness of a thyroid nodule; however, it is a subjective method, and findings depend on the size and location of the nodule as well as the examiner’s skill [13]. Elastography is a recently introduced noninvasive technique which estimates the stiffness of tissues by assessing distortion under compression [14], [15]. US elastography has been successfully applied in the breast and more recently in the prostate gland [16]. Previous ex vivo and in vivo studies have documented significant differences in stiffness of normal thyroid tissue and tumors of the thyroid gland [17], [18]. However, out-of-plane motion of the nodule during external compression and compression of the thyroid gland due to pulsation of the carotid artery may limit this technique [17]. Carotid pulsation has also been used as a source of compression for elastography of the thyroid gland [19], [20].
In this study, we aimed to determine the diagnostic value of US elastography in the differentiation of malignant and benign thyroid nodules using carotid artery pulsation as the source of compression.
Section snippets
Patients
The study protocol was approved by the institutional ethical committee, and informed consent was obtained from the patients. The patients who were diagnosed with a thyroid nodule and had an indication for an FNAB were included into the study. The patients were selected prospectively and consecutively. The patients who did not have a final histopathological or cytological diagnosis were excluded from the study.
Lesion evaluation
US elastography examinations were performed using a 5–13-MHz linear transducer (Acuson
Results
A total of 110 thyroid nodules of 99 patients were included in the study. Five nodules from five patients were excluded from the study because of insufficient material as the final cytological result. Two nodules from one patient were also excluded because the patient was lost after a diagnosis of suspicious findings for malignancy with FNAB. A total of 103 nodules from 93 patients (24 men, 69 women) were analyzed in the study. The mean age of the patients was 52.8±12.5 years (ranging between 24
Discussion
Advances in imaging techniques have increased the number of documented thyroid nodules considerably; however, characterization of the lesion accurately is not always possible [23], [24]. In determination of the malignant lesion, presence of microcalcifications, irregular margins, and intranodular (type III) vascularization are reported to have a high specificity but low sensitivity [25], [26]. Despite its advantages, US-guided FNAB is an invasive procedure which may cause sampling errors,
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US Elastography Using Carotid Artery Pulsation May Increase the Diagnostic Accuracy for Thyroid Nodules with US-Pathology Discordance
2017, Ultrasound in Medicine and BiologyCitation Excerpt :Although there was a degree of overlap in the ECI values between benign and malignant nodules, all benign nodules had ECI values of <3.5 except for three completely calcified nodules and one rim-calcified nodule; that is, thyroid nodules with ECI values of >3.5 had a high specificity and PPV for the diagnosis of thyroid cancer, thereby increasing the diagnostic accuracy. USE using carotid artery pulsation is a technique that uses the natural pulsation of the carotid artery as the internal compression source (Akcay et al. 2014; Bae et al. 2007; Choi et al. 2015; Dighe et al. 2008, 2013; Kim et al. 2014; Lim et al. 2012). Since this technique uses information from 3∼4 cardiac cycles of diastolic and systolic pulsation and measures the deformation in response to an applied force from the carotid artery, it can eliminate the noise caused by external compression (Bae et al. 2007; Dighe et al. 2008) and potentially provide more operator-independent images.
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