Differentiation between Benign and Malignant Solid Thyroid Nodules Using an US Classification System

Objective

To evaluate the diagnostic accuracy of a new ultrasound (US) classification system for differentiating between benign and malignant solid thyroid nodules.

Materials and Methods

In this study, we enrolled 191 consecutive patients who received real-time US and subsequent US diagnoses for solid thyroid nodules, and underwent US-guided fine-needle aspiration. Each thyroid nodule was prospectively classified into 1 of 5 diagnostic categories by real-time US: "malignant," "suspicious for malignancy," "borderline," "probably benign," and "benign". We evaluated the diagnostic accuracy of thyroid US and the cut-off US criteria by comparing the US diagnoses of thyroid nodules with cytopathologic results.

Results

Of the 191 solid nodules, 103 were subjected to thyroid surgery. US categories for these 191 nodules were malignant (n = 52), suspicious for malignancy (n = 16), borderline (n = 23), probably benign (n = 18), and benign (n = 82). A receiver-operating characteristic curve analysis revealed that the US diagnosis for solid thyroid nodules using the 5-category US classification system was very good. The sensitivity, specificity, positive and negative predictive values, and accuracy of US diagnosis were 86%, 95%, 91%, 92%, and 92%, respectively, when benign, probably benign, and borderline categories were collectively classified as benign (negative).

Conclusion

The diagnostic accuracy of thyroid US for solid thyroid nodules is high when the above-mentioned US classification system is applied.     

Hyperfunction Thyroid Nodules: Their Risk for Becoming or Being Associated with Thyroid Cancers

Objective

To retrospectively evaluate the risk of thyroid cancer in patients with hyperfunctioning thyroid nodules through ultrasonographic-pathologic analysis.

Materials and Methods

Institutional review board approval was obtained and informed consent was waived. From 2003 to 2007, 107 patients consecutively presented with hot spots on thyroid scans and low serum thyroid-stimulating hormone levels. Among them, 32 patients who had undergone thyroid ultrasonography were analyzed in this study. Thyroid nodules depicted on ultrasonography were classified based on size and categorized as benign, indeterminate, or suspicious malignant nodules according to ultrasonographic findings. The thyroid nodules were determined as either hyperfunctioning or coexisting nodules and were then correlated with pathologic results.

Results

In 32 patients, 42 hyperfunctioning nodules (mean number per patient, 1.31; range, 1-6) were observed on thyroid scans and 68 coexisting nodules (mean, 2.13; range, 0-7) were observed on ultrasonography. Twenty-five patients (78.1%) had at least one hyperfunctioning (n = 17, 53.1%) or coexisting (n = 16, 50.0%) nodule that showed a suspicious malignant feature larger than 5 mm (n = 8, 25.0%), or an indeterminate feature 1 cm or greater (n = 20, 62.5%) in diameter, which could have been indicated by using fine needle aspiration (FNA). Seven patients were proven to have 11 thyroid cancers in 3 hyperfunctioning and 8 coexisting nodules. All of these had at least one thyroid cancer, which could have been indicated by using FNA. The estimated minimal risk of thyroid cancer was 6.5% (7/107).

Conclusion

Patients with hyperfunctioning nodules may not be safe from thyroid cancer because hyperfunctioning nodules can coexist with thyroid cancer nodules. To screen out these cancers, ultrasonography should be performed.     

Suspiciously malignant findings on ultrasound after fine needle aspiration biopsy in a thyroid nodule with initially benign ultrasound and cytologic result: to repeat or to follow-up

Purpose

The purposes of this study were to evaluate the incidence of suspiciously malignant change on ultrasound (US) in thyroid nodules after initial benign US and cytologic results and to investigate the associated US characteristics and the management of these nodules.

Materials and methods

Among the patients who underwent thyroid fine needle aspiration biopsy (FNAB) from October 2003 to December 2004, 550 patients who had thyroid nodules with initial benign US and cytologic results were included. Reference standards were established by pathologic results, follow-up cytologic results or follow-up US. We evaluated the incidence of morphologic changes to suspiciously malignant US findings of these thyroid nodules after FNAB. We also evaluated the initial US features associated with the nodules showing suspiciously malignant findings on US after FNAB in these patients.

Results

Of 550 patients, 28 nodules (5.1%) showed morphologic changes into nodules with suspiciously malignant US findings on follow-up US. All thyroid nodules showing morphologic changes had mixed solid and cystic components (P<.001). Suspiciously malignant changes on US were associated with the percentage of the cystic portion, but all changed nodules were confirmed as benign.

Conclusion

Follow-up US should be recommended rather than to repeat FNAB for thyroid nodules with initial benign US and cytologic results even if they later develop suspiciously malignant US features after FNAB.     

Thyroid incidentalomas on fluorine-18-fluorodeoxyglucose positron emission tomography-computed tomography: incidence, malignancy risk, and comparison of standardized uptake values

Introduction

To determine the incidence of fluorine-18-fluorodeoxyglucose (FDG) avid thyroid incidentalomas detected on positron emission tomography (PET) with integrated computed tomography (CT), and correlate the FDG–PET-CT findings to cytology.

Methods

A total of 942 FDG–PET-CT reports were retrospectively reviewed. Patients with FDG-avid thyroid incidentalomas were further reviewed for correlative cytology.

Results

The incidence of FDG-avid thyroid incidentalomas is 2.2%. Thyroid malignancies were identified in 3 of 6 patients who underwent cytologic correlation, with a positive predictive value of 50% (95% confidence interval, 14%-86%). The mean maximum standardized uptake values of benign and malignant FDG-avid thyroid incidentalomas were 5.6 and 6.6, respectively.

Conclusion

A FDG-avid thyroid incidentaloma may predict underlying malignancy. Cytologic assessment should be considered for FDG-avid thyroid incidentalomas.     

Partially Cystic Thyroid Nodules: Ultrasound Findings of Malignancy

Objective

To seek for the ultrasound (US) findings of partially cystic thyroid nodules that are associated with malignancy.

Materials and Methods

We reviewed the US characteristics of 22 surgically confirmed partially cystic papillary carcinomas, and compared them with those of 80 benign partially cystic nodules. The review cases were selected in a random order from a total of 1029 partially cystic nodules that were diagnosed with an US-guided fine needle aspiration biopsy over a period of 8 years (June 2003 to October 2010) at our institution.

Results

In partially cystic thyroid nodules, a taller-than-wide shape (100%, p < 0.001) and spiculated or microlobulated margin (58.3%, p = 0.003) were significantly associated with malignancy. In terms of internal solid portion of the nodule, eccentric configuration (68.0%, p < 0.001), non-smooth margin (81.3%, p < 0.001), hypoechogenecity (30.0%, p < 0.042), and microcalcification (89.5%, p < 0.001) were more frequently demonstrated in malignant nodules than benign ones.

Conclusion

In partially cystic thyroid nodules, understanding the characteristics of US findings is important to make a precise diagnosis of malignant nodules.     

Risk of Thyroid Cancer in Euthyroid Asymptomatic Patients with Thyroid Nodules with an Emphasis on Family History of Thyroid Cancer

Objective

To determine the factors associated with thyroid cancer, focusing on first-degree family history and ultrasonography (US) features, in euthyroid asymptomatic patients with thyroid nodules.

Materials and Methods

This retrospective study included 1310 thyroid nodules of 1254 euthyroid asymptomatic patients who underwent US-guided fine-needle aspiration biopsy between November 2012 and August 2013. Nodule size and clinical risk factors–such as patient age, gender, first-degree family history of thyroid cancer, multiplicity on US and serum thyroid stimulating hormone (TSH) levels–were considered together with US features to compare benign and malignant nodules. Multiple logistic regression analysis was performed to assess the risk of thyroid malignancy according to clinical and US characteristics.

Results

Although all of the clinical factors and US findings were significantly different between patients with benign and malignant nodules, a solitary lesion on US (p = 0.041–0.043), US features and male gender (p < 0.001) were significant independent risk factors for thyroid malignancy in a multivariate analysis. Patient age, a first-degree family history of thyroid cancer and high normal serum TSH levels did not independently significantly increase the risk of thyroid cancer. However, multicollinearity existed between US assessment and patient age, first-degree family history of thyroid cancer and serum TSH values.

Conclusion

Ultrasonography findings should be the primary criterion used to decide the management of euthyroid asymptomatic patients with thyroid nodules. The concept of first-degree family history as a risk factor for thyroid malignancy should be further studied in asymptomatic patients.     

Differentiation of benign from malignant thyroid nodules with acoustic radiation force impulse technique

Objective:

The aim of our study was to assess the performance of acoustic radiation force impulse (ARFI) imaging to differentiate benign from malignant thyroid nodules.

Methods:

182 patients who needed thyroid surgery were examined. All patients and 50 healthy volunteers underwent ARFI sonoelastography, which quantitatively analysed the elasticity and hardness of the nodule''s centre and periphery.

Results:

ARFI values showed a statistical significance between malignant nodules and benign nodules and common thyroid parenchyma, in both the centre and periphery of nodules (p < 0.01). There was no significant difference between benign nodules and common thyroid parenchyma in either the nodule''s centre or periphery (p > 0.05). There was no significant difference between the nodule''s centre and periphery of the elastic parameters in both the benign and malignant nodules. There was a statistically significant difference among the two areas (the central group and the peripheral group) under the receiver operating characteristic curve, and the optimal model was the peripheral group. For differentiation of malignant from benign nodules, the sensitivity and specificity were 96.3% and 96.2%, respectively, when 2.545 m s⁻¹ was chosen as a cut-off value in the peripheral group.

Conclusion:

ARFI imaging may be helpful to differentiate benign nodules from malignant thyroid nodules. The selecting measurement position is important in ARFI imaging, and it has good diagnostic value in clinical applications.

Advances in knowledge:

This study shows the diagnostic contribution of ARFI imaging in thyroid lesions.Thyroid cancer is the most common endocrine malignancy, and its incidence has increased in recent years.¹ It comprises different clinical and histological features in respect to different treatments.² The diagnostic method for thyroid cancer has very quickly progressed in recent years, but the pre-operative misdiagnosis rate is 40–70%.A newer ultrasound elastography technique called acoustic radiation force impulse (ARFI), which is performed under direct visual guidance, has recently been verified to measure the stiffness of many tissues in vivo, for example in the liver.^3,4 In our study, we investigated the mechanical properties of focal thyroid disease with ARFI. The purposes of this study were to assess the effectiveness of ARFI quantification in the diagnosis of focal thyroid nodules and differentiation of benign from malignant thyroid lesions by quantification of their stiffness.     

Role of Duplex Power Doppler Ultrasound in Differentiation between Malignant and Benign Thyroid Nodules

Objective

To evaluate the usage of duplex power Doppler ultrasound (PDUS) for the differentiation of benign and malignant thyroid nodules.

Materials and Methods

We prospectively examined 77 thyroid nodules in 60 patients undergoing ultrasound-guided fine needle aspiration biopsy (FNAB). Each nodule was described according to size, inner structure, borders, parenchymal echogenicity, peripheral halo formation, and the presence of calcification (B-mode ultrasound findings). Vascularity as determined by PDUS imaging was defined as non-vascular, peripheral, central, or of mixed type. For each nodule, the pulsatility index (PI) and resistive index (RI) values were obtained. Results of FNAB and surgical pathological examination (if available) were used as a proof of final diagnosis to categorize all nodules as benign or malignant. A receiver operating characteristic (ROC) curve analysis was performed to establish cut-off, sensitivity, and specificity values associated with RI-PI values.

Results

A significant relationship was observed between malignancy and irregular margins, microcalcifications, and hypoechogenicity on ultrasound examination (p < 0.05). The pattern of vascularity as determined by PDUS analysis was not a statistically significant criterion to suggest benign or malignant disease in this study (p > 0.05). The central, peripheral, and mean RI-PI values were higher in malignant nodules when compared to the other cytologies (p < 0.05).

Conclusion

Vascularity is not a useful parameter for distinguishing malignant from benign thyroid nodules. However, RI and PI values are useful in distinguishing malignant from benign thyroid nodules.     

Observer Variability and the Performance between Faculties and Residents: US Criteria for Benign and Malignant Thyroid Nodules

Objective

To evaluate the interobserver variability and performance in the interpretation of ultrasonographic (US) findings of thyroid nodules.

Materials and Methods

72 malignant nodules and 61 benign nodules were enrolled as part of this study. Five faculty radiologists and four residents independently performed a retrospective analysis of the US images. The observers received one training session after the first interpretation and then performed a secondary interpretation. Agreement was analyzed by Cohen''s kappa statistic. Degree of performance was analyzed using receiver operating characteristic (ROC) curves.

Results

Agreement between the faculties was fair-to-good for all criteria; however, between residents, agreement was poor-to-fair. The area under the ROC curves was 0.72, 0.62, and 0.60 for the faculties, senior residents, and junior residents, respectively. There was a significant difference in performance between the faculties and the residents (p < 0.05). There was a significant increase in the agreement for some criteria in the faculties and the senior residents after the training session, but no significant increase in the junior residents.

Conclusion

Independent reporting of thyroid US performed by residents is undesirable. A continuous and specialized resident training is essential to enhance the degree of agreement and performance.     

Ultrasound-Guided Fine-Needle Aspiration Biopsy of Thyroid Nodules Smaller Than 5 mm in the Maximum Diameter: Assessment of Efficacy and Pathological Findings

Objective

The aim of this study was to determine the efficacy of the use of an ultrasound-guided fine-needle aspiration biopsy (US-FNAB) to diagnose thyroid nodules smaller than 5 mm in the maximum diameter and to evaluate pathological findings of small thyroid malignancies.

Materials and Methods

From May 2007 to April 2008, we evaluated the findings of US-FNABs of small thyroid nodules less than 5 mm in the maximum diameter. The cytopathological findings were retrospectively reviewed and the diagnostic performance of the use of an US-FNAB was examined in all patients.

Results

Of 201 small thyroid nodules in 180 patients, there were 162 adequate specimens (81%). Among 180 patients, 75 patients underwent thyroid surgery and 50 malignant and 33 benign nodules were identified based on a pathological examination. All small malignant thyroid nodules were identified as papillary thyroid microcarcinomas (PTMCs). There were 34 (55%) true positive, 0 (0%) false positive, 23 (37%) true negative and five (8%) false negative results for malignancy after performing a first US-FNAB in 62 surgically confirmed nodules. The sensitivity (87%), specificity (100%), positive predictive value (100%), negative predictive value (82%), accuracy (92%), false positive rate (0%) and false negative rate (8%) for an US-FNAB were determined. In 23 patients with a primary PTMC, capsular invasion (9%, 2 of 23), a perithyroidal lymph node metastasis (30%, 7 of 23), the rate of multifocality (9%, 2 of 23) and bilaterality (4%, 1 of 23) were also determined.

Conclusion

An US-FNAB of thyroid nodules smaller than 5 mm in the maximum diameter is an effective diagnostic procedure.     

Role of combined grey scale US and US tissue elastography in differentiating solid thyroid nodules

Background

Ultrasonographic (US) examination is an accurate method for detecting thyroid nodules, but its use in differentiating between benign and malignant thyroid nodules is relatively low. US elastography has been applied to study the hardness/elasticity of nodules to differentiate malignant from benign lesions thus deviating a significant group of patients from unnecessary FNAB.

Objectives

The aim of the study is to evaluate the validity of combined grey scale US and tissue elastography in differentiating benign form malignant solid thyroid nodules.

Methods

The study included 46 selected patients with solid thyroid nodules according to our inclusion and exclusion criteria. The patients underwent surgery for compressive symptoms or suspicion of malignancy on FNA cytology. US features and tissue elastography were scored according to the Rago criteria (1).

Results

On US elastography: all the 31 cases with a final diagnosis of benign nodule had a score of 1–3, while 14 of 15 (94.1%) with a final diagnosis of carcinoma had a score of 4–5, with a sensitivity of 93.3%, a specificity of 100% and an accuracy of 97.8%. Combined US and elastography reveals that hypoechogenicity/score 4–5 was most predictive of malignancy with sensitivity 80% and specificity 100%; and accuracy 93.4%.

Conclusions

US elastography seems to have great potential as a new tool for differentiating solid thyroid nodules and for recommending FNAC. Combined grey scale US features and US elastography added no significant value when compared with US elastography alone. Further prospective studies are needed.     

Inter-Observer Variation in Ultrasound Measurement of the Volume and Diameter of Thyroid Nodules

Objective

Thyroid nodule measurement using ultrasonography (US) is widely performed in various clinical scenarios. The purpose of this study was to evaluate inter-observer variation in US measurement of the volume and maximum diameter of thyroid nodules.

Materials and Methods

This retrospective study included 73 consecutive patients with 85 well-defined thyroid nodules greater than 1 cm in their maximum diameter. US examinations were independently performed by using standardized measurement methods, conducted by two clinically experienced thyroid radiologists. The maximum nodule diameter and nodule volume, calculated from nodule diameters using the ellipsoid formula, were obtained by each reader. Inter-observer variations in volume and maximum diameter were determined using 95% Bland-Altman limits of agreement. The degree of inter-observer variations in volumes and the maximum diameters were compared using the Student''s t test, between nodules < 2 cm in maximum diameter and those with ≥ 2 cm.

Results

The mean inter-observer difference in measuring the nodule volume was -1.6%, in terms of percentage of the nodule volume, and the 95% limit of agreement was ± 13.1%. For maximum nodule diameter, the mean inter-observer difference was -0.6%, in terms of percentage of the nodule diameter, and the 95% limit of agreement was ± 7.3%. Inter-observer variation in volume was greater in nodules of < 2 cm in maximum diameter, compared to the larger nodules (p = 0.035). However, no statistically significant difference was noted between the two groups regarding maximum nodule diameters (p = 0.511).

Conclusion

Any differences smaller than 13.1% and 7.3% in volume and maximum diameter, respectively, measured by using US for well-defined thyroid nodules of > 1 cm should not be considered as a real change in size.     

Ultrasonographic criteria for fine needle aspiration of nonpalpable thyroid nodules 1–2 cm in diameter

Purpose

To investigate the ultrasonographic (US) characteristics for nonpalpable thyroid nodules 1–2 cm in diameter and to evaluate the guideline for fine needle aspiration (FNA) in terms of US findings.

Materials and methods

Between June 2005 and November 2006, FNA was performed in 919 thyroid nodules by radiologists. Of these nodules, 51 malignant nodules and 72 benign nodules were finally included. All 123 nodules were analyzed by 3 radiologists if there were the following US characteristics: marked hypoechogenecity, hypoechogenecity, isoechogenecity, hyperechogenecity, microcalcification, coarse calcification, rim calcification, spiculated margin, taller-than-wide shape, irregular shape, hypoechoic rim and honeycomb appearance. The maximum diameters of nodules and thickness of hypoechoic rim were measured. US characteristics relevant as predictors were identified using a Chi-square or Fisher's exact test and odds ratio. We compared the diagnostic efficacy of 3 US criteria for FNA indication.

Results

Microcalcification, taller-than-wide shape, marked hypoechogenecity, hypoechogenecity, coarse calcification, irregular shape and spiculated margin were significant characteristics of malignant nodules. Isoechogenecity, hypoechoic rim and honeycomb appearance was significant characteristics of benign nodules. Rim or arc calcification, hyperechogenecity and thickness of hypoechoic rim were insignificant. Among 3 US criteria for FNA indication, NFI showed the highest diagnostic efficacy, 98.0% in sensitivity, 75.0% in specificity and 150.0 in odds ratio.

Conclusion

As for nonpalpable thyroid nodules 1–2 cm in diameter, US characteristics are useful for differentiating between malignant and benign nodules. Malignant US characteristics and honeycombing appearance have significant value in selecting nodules for biopsy and reducing the frequency of the FNA procedure.     

Diagnostic performance of combined elastosonography scoring and high-resolution ultrasonography for the differentiation of benign and malignant thyroid nodules

Aim

To evaluate the diagnostic performance of the combined use of elstosonography (USE) scoring and high-resolution ultrasonography (HRUS) for the differentiation of benign and malignant thyroid nodule.

Patients and methods

Forty-seven consecutive patients with 66 thyroid nodules were enrolled in the present study. Thyroid surgery had been already planned for all the patients. All of them were submitted to high-resolution ultrasonography and elastography scoring at the same sitting. The latter was determined with 5-point scoring method. The examination results were compared against pathological findings as the gold standard of reference.

Results

The sensitivity, specificity, accuracy, positive predictive, and negative predictive values of HRUS in the differential diagnosis of thyroid nodules were 92.0%, 72.9%, 60.1%, 95.0%, and 63.1%, respectively, while that of ultrasound elastography scoring were 75.4%, 85.5%, 86.7%, 71.4%, and 90.5%, respectively. Combined use of both US techniques resulted in a higher diagnostic performance as it showed 95.4%, 94.8%, 95.2%, 82.3% and 98.8% sensitivity, specificity, accuracy, positive predictive, and negative predictive values, respectively.

Conclusions

The use of combined USE and HRS for the differentiation of benign and malignant thyroid nodules resulted in a high diagnostic performance and a significant statistical difference as compared to HRUS or USE alone (P = 0.003).     

Differential Diagnosis of Benign and Malignant Intraductal Papillary Mucinous Tumors of the Pancreas: MR Cholangiopancreatography and MR Angiography

Objective

To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy.

Materials and Methods

During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA.

Results

Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p < 0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p < 0.05), and the presence of mural nodules was more frequent (p < 0.001).

Conclusion

Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas.     

Role of quantitative diffusion-weighted MRI and H MR spectroscopy in distinguishing between benign and malignant thyroid nodules

Background and purpose

The imaging characterization of thyroid nodules is mandatory to exclude malignancy. The purpose of this study is to evaluate the role of quantitative diffusion MRI and ¹H MR spectroscopy in differentiation between benign and malignant Thyroid nodules.

Methods

From February 2012 to May 2013, prospective study was conducted on 25 patients with 41 thyroid nodules (11 males, 14 females, age range, 16–74 years with mean 45.3 years) collected from wards and clinics of Internal Medicine and General Surgery Departments, 20 healthy individuals as control cases were included in the study. 1.5-T ¹H-MR spectroscopy (at echo-times (TE) 144 and 35 ms) and diffusion-weighted imaging (b value 0, 250 and 1000 s/mm²) were performed and the results were correlated with histopathological results.

Results

The mean ADC of the malignant thyroid nodules (13 nodules) was 0.59 ± 0.24 × 10⁻³ mm²/s while that of the benign thyroid nodules (28 nodules) was 1.78 ± 0.21 × 10⁻³ mm²/s (p value <0.0001).Choline is present in all malignant nodules (13 nodules) and two benign nodules (mild elevation) while absent in 26 other benign nodules. Choline/creatine ratio in malignant nodules ranged from 1.3 to 5.4, while in two benign nodules it was 0.9 and 1.1.The sensitivity, specificity, PPV, NPV and overall accuracy of diffusion and MRS in differentiating benign from malignant thyroid nodules were 100%, 93%, 96%, 100% and 79%, respectively.

Conclusion

MRS and diffusion WI are useful noninvasive diagnostic modalities in differentiation between benign and malignant thyroid nodules.     

The clinical value of ultrasound elastography in predicting malignant thyroid nodules

Objective

This study aims to evaluate the clinical value of ultrasound elastography (USE) in providing information on the nature of the thyroid nodules. This was performed using the elastography score and strain ratio in differentiating thyroid benign and malignant nodules and the histopathological examination was used as the diagnostic standard of reference.

Methods

We examined 84 thyroid nodules in 62 patients with ultrasound elastography. Elastography score was assigned based on a four-point scale according to the classification proposed by Itoh et al. with a score of 1 (low stiffness over the entire nodule) to a score of 4 (high stiffness over the entire nodule). Thyroid strain ratio (normal tissue to lesion strain ratio) was calculated. Histopathological results were the standard reference. The area under the curve (AUC) and the best cut-off point were both obtained using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, and accuracy of both techniques were calculated.

Results

Fifty-four of the 84 nodules had scores of 1 and 2, and 50 of these nodules were diagnosed histopathologically as benign. Thirty of the 84 nodules had a score of 3 and 4, and 21 of these nodules were diagnosed histopathologically as malignant. The scores of 1 and 2 with Itoh criteria were significantly seen in benign nodules, whereas, scores of 3 and 4 were significantly seen in malignant nodules (p < 0.05) with sensitivity 84%, specificity 84.7%, PPV 70%, NPV 92.6% and accuracy 84.5%. The mean SR for the benign nodules and malignant ones was significantly different (2.92 ± 0.96 vs. 4.53 ± 0.82, p < 0.001). With ROC analysis, the best cut-off strain ratio point was 3.5 for differentiating benign and malignant nodules with area under the curve (AUC) = 0.87 (0.8–0.95). The sensitivity of the strain ratio was 88%, while the specificity was 86.4%, PPV = 73.3%, NPV = 94.4% and accuracy = 86.9%.

Conclusions

Both the elastographic score and strain ratio are higher in malignant nodules than those in benign ones. Ultrasound elastography can provide quantitative information on thyroid nodule helping in differentiating benign and malignant ones.     

Shear wave elastography of thyroid nodules in routine clinical practice: preliminary observations and utility for detecting malignancy

Objective

To evaluate real-time shear wave ultrasound elastography (SWE) for characterizing focal thyroid lesions in routine clinical practice.

Methods

Seventy-four patients with 81 focal thyroid lesions undergoing conventional US with needle cytology also underwent SWE. Absolute and relative SWE stiffness measurements on colour-coded elastograms were correlated with cytology and their discriminatory performances assessed.

Results

Seventeen nodules were malignant (13 papillary, 4 other cancers), 45 benign (43 hyperplastic nodules, 2 focal thyroiditis), 5 indeterminate (“follicular lesions”), and 5 had inadequate cytology. SWE results were higher in malignant than benign nodules (P values 0.02–0.05) although their discriminatory performances were mediocre (AUCs 0.58–0.74). The most accurate SWE cut-off, 34.5 kPa for a 2-mm region of interest, achieved 76.9?% sensitivity and 71.1?% specificity for discriminating papillary cancer from benign nodules. No thresholds produced high sensitivity without lowering specificity appreciably, and vice versa. Nodule size correlated with SWE for benign nodules (P?<?0.01). Intranodular cystic change or calcification did not influence SWE. Qualitatively, elastographic artefacts and foci lacking colour elasticity signal occurred in some solid nodules.

Conclusion

Although malignant nodules are generally stiffer than benign nodules, the precision results do not suggest a definitive role for SWE, at present, in identifying or excluding thyroid malignancy.

Key Points

? Shear wave ultrasound elastography (SWE) offers new insight into thyroid disease. ? Papillary cancers have higher SWE indices (equating to higher stiffness) than benign nodules. ? SWE appears limited in terms of identifying or excluding thyroid malignancy accurately. ? Vertically aligned elastographic artefacts can occur in thyroid SWE. ? Areas lacking SWE colour signal can occur in some solid thyroid nodules.     

US, colour-Doppler US and fine-needle aspiration biopsy in the diagnosis of thyroid nodules

PURPOSE: The purpose of this study was to correlate the diagnosis of benign or malignant thyroid nodules obtained with grey-scale ultrasound (US) and colour-Doppler US with the cytological findings after US-guided fine-needle aspiration (FNA). MATERIALS AND METHODS: Between January 2004 and June 2005, 516 thyroid nodules in 420 patients (181 solitary thyroid nodules and 239 multiple nodules) were prospectively evaluated with US, colour-Doppler US and US-guided FNA. The nodules were classified as sonographically benign, suspicious or malignant in accordance with established US criteria. Cytological findings were classified as inadequate, benign, indeterminate, suspicious or malignant. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of US and colour-Doppler US were evaluated using FNA as the reference procedure. RESULTS: The sensitivity, specificity, PPV, NPV and overall accuracy values of grey-scale US were 46%, 73%, 34%, 82% and 67%, respectively, for solitary thyroid nodules and 35%, 72%, 14%, 90% and 68%, respectively, for multiple nodules. The evaluation of nodule vascularity with colour-Doppler US produced a slight increase in sensitivity but a slight reduction in specificity. CONCLUSIONS: Thyroid nodules cannot be accurately characterised using grey-scale US or colour-Doppler US.