Gray-scale and color Doppler ultrasonographic manifestations of papillary thyroid carcinoma: analysis of 51 cases

Markedly hypoechoic: a new definition improves the diagnostic performance of thyroid ultrasound

OBJECTIVES

To determine the contribution of a modified definition of markedly hypoechoic in the differential diagnosis of thyroid nodules.

METHODS

A total of 1031 thyroid nodules were included in this retrospective multicenter study. All of the nodules were examined with US before surgery. The US features of the nodules were evaluated, in particular, the classical markedly hypoechoic and modified markedly hypoechoic (decreased or similar echogenicity relative to the adjacent strap muscles). The sensitivity, specificity, and AUC of classical/modified markedly hypoechoic and the corresponding ACR-TIRADS, EU-TIRADS, and C-TIRADS categories were calculated and compared. The inter- and intraobserver variability in the evaluation of the main US features of the nodules was assessed.

RESULTS

There were 264 malignant nodules and 767 benign nodules. Compared with classical markedly hypoechoic as a diagnostic criterion for malignancy, using modified markedly hypoechoic as the criterion resulted in a significant increase in sensitivity (28.03% vs. 63.26%) and AUC (0.598 vs. 0.741), despite a significant decrease in specificity (91.53% vs. 84.88%) (p < 0.001 for all). Compared to the AUC of the C-TIRADS with the classical markedly hypoechoic, the AUC of the C-TIRADS with the modified markedly hypoechoic increased from 0.878 to 0.888 (p = 0.01); however, the AUCs of the ACR-TIRADS and EU-TIRADS did not change significantly (p > 0.05 for both). There was substantial interobserver agreement (κ = 0.624) and perfect intraobserver agreement (κ = 0.828) for the modified markedly hypoechoic.

CONCLUSION

The modified definition of markedly hypoechoic resulted in a significantly improved diagnostic efficacy in determining malignant thyroid nodules and may improve the diagnostic performance of the C-TIRADS.

CLINICAL RELEVANCE STATEMENT

Our study found that, compared with the original definition, modified markedly hypoechoic significantly improved the diagnostic performance in differentiating malignant from benign thyroid nodules and the predictive efficacy of the risk stratification systems.

KEY POINTS

• Compared with the classical markedly hypoechoic as a diagnostic criterion for malignancy, the modified markedly hypoechoic resulted in a significant increase in sensitivity and AUC. • The C-TIRADS with the modified markedly hypoechoic achieved higher AUC and specificity than that with the classical markedly hypoechoic (p = 0.01 and  < 0.001, respectively).

ACR TI-RADS classification combined with number of nodules, halo features optimizes diagnosis and prediction of follicular thyroid cancer

OBJECTIVES

To investigate the application value of The American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) category combined with other ultrasound features of nodules in distinguishing follicular thyroid carcinoma (FTC) from thyroid follicular adenoma (FTA).

METHODS

We collected and retrospectively analyzed clinical and ultrasound data for 118 and 459 patients with FTCs and FTAs, respectively, at our hospital. Next, we used ACR TI-RADS classification combined with other ultrasound features of nodules to distinguish FTC from FTA. Multivariate Logistic regression was used to screen independent risk factors for FTC, which were subsequently used to construct a nomogram for predicting FTC.

RESULTS

ACR TI-RADS categories 4 and 5, unilateral multiple nodules, and halo thickness≥2 mm were independent risk factors for FTC. ACR TI-RADS category combined with number of nodules, halo features of the nodule was a significantly better prediction model for FTC diagnosis (AUC = 0.869) than that of ACR TI-RADS classification alone (AUC = 0.756).

CONCLUTIONS

Clinicians need to pay attention to the halo of nodules when distinguishing FTA from FTC. Notably, ACR TI-RADS combined with other nodule ultrasound features has superior predictive performance in diagnosis of FTC compared to ACR TI-RADS classification alone, thus can provide an important reference value for preoperative diagnosis of FTC.

2020 Chinese guidelines for ultrasound malignancy risk stratification of thyroid nodules: the C-TIRADS

Thyroid nodules are very common all over the world, and China is no exception. Ultrasound plays an important role in determining the risk stratification of thyroid nodules, which is critical for clinical management of thyroid nodules. For the past few years, many versions of TIRADS (Thyroid Imaging Reporting and Data System) have been put forward by several institutions with the aim to identify whether nodules require fine-needle biopsy or ultrasound follow-up. However, no version of TIRADS has been widely adopted worldwide till date. In China, as many as ten versions of TIRADS have been used in different hospitals nationwide, causing a lot of confusion. With the support of the Superficial Organ and Vascular Ultrasound Group of the Society of Ultrasound in Medicine of the Chinese Medical Association, the Chinese-TIRADS that is in line with China's national conditions and medical status was established based on literature review, expert consensus, and multicenter data provided by the Chinese Artificial Intelligence Alliance for Thyroid and Breast Ultrasound.

Neoplastic pathology at the crossroads between neck imaging and cardiothoracic imaging

The thoracic inlet is located at the crossroads between imaging of the neck and the chest. Its location is an important anatomic landmark, serving as the central conducting pathway for many vital structures extending from the neck into the chest and vice versa. Many critical body systems, including the respiratory, lymphatic, neurologic, enteric, musculoskeletal, endocrine, and vascular systems, are located within this region. Neoplasms, both benign and malignant, can arise in any of the body systems located in this area. Due to the small size of this anatomic location, pathology is easily overlooked and imagers should be aware of the imaging appearance of these neoplasms, as well as which imaging modality is the most appropriate for neoplasm evaluation. This article will present an image rich, system-based discussion of the neoplastic pathology that can occur in this region. The anatomy of the thoracic inlet and the non-neoplastic pathology of the thoracic inlet have been covered in our companion article.

Multi-Reader Multi-Case Study for Performance Evaluation of High-Risk Thyroid Ultrasound with Computer-Aided Detection

Physicians use sonographic characteristics as a reference for the possible diagnosis of thyroid cancers. The purpose of this study was to investigate whether physicians were more effective in their tentative diagnosis based on the information provided by a computer-aided detection (CAD) system. A computer compared software-defined and physician-adjusted tumor loci. A multicenter, multireader, and multicase (MRMC) study was designed to compare clinician performance without and with the use of CAD. Interobserver variability was also analyzed. Excellent, satisfactory, and poor segmentations were observed in 25.3%, 58.9%, and 15.8% of nodules, respectively. There were 200 patients with 265 nodules in the study set. Nineteen physicians scored the malignancy potential of the nodules. The average area under the curve (AUC) of all readers was 0.728 without CAD and significantly increased to 0.792 with CAD. The average standard deviation of the malignant potential score significantly decreased from 18.97 to 16.29. The mean malignant potential score significantly decreased from 35.01 to 31.24 for benign cases. With the CAD system, an additional 7.6% of malignant nodules would be suggested for further evaluation, and biopsy would not be recommended for an additional 10.8% of benign nodules. The results demonstrated that applying a CAD system would improve clinicians’ interpretations and lessen the variability in diagnosis. However, more studies are needed to explore the use of the CAD system in an actual ultrasound diagnostic situation where much more benign thyroid nodules would be seen.

Vascular flow on doppler sonography may not be a valid characteristic to distinguish colloid nodules from papillary thyroid carcinoma even when accounting for nodular size

Background

The purpose of this study was to test the hypothesis that there is no significant difference in vascular flow patterns between cytopathologically-proven colloid nodules and papillary thyroid carcinoma (PTC) even when adjusting for nodule size.

Methods

Doppler vascular flow patterns in 200 colloid nodules and 166 nodules with PTC were retrospective reviewed independently by 2 neuroradiologists blinded to the cytopathological results. Absence of vascular flow, perinodular and/or intranodular flow, and diffuse vascular flow were recorded. The vascular flow patterns were compared without (Fisher exact test) and with (Kruskal-Wallis test) an adjustment for nodular size. Using the most common flow pattern as the reference group, multiple logistic regression was used to compare the flow patterns. Sample skewness was calculated to determine degree of symmetry of the size distribution for each vascular flow category.

Results

No significant difference was found in the tested vascular flow patterns between colloid nodules and PTC both without and with an adjustment for nodular size (P>0.05). Intranodular flow only was the largest group (n=111/366) and used as the reference for multiple logistic regression. No significant difference was noted between the vascular flow patterns (P>0.05). Sample skewness showed that nodules were generally smaller in size with outliers of larger size on the opposite end of the spectrum.

Conclusions

Independent of nodule size the absence or presence of vascular flow is not significantly different between colloid nodules and PTC. Therefore, vascular flow may not be useful in distinguishing between colloid nodules and PTC.

Color Doppler ultrasonography diagnostic value in detection of malignant nodules in cysts with pathologically proven thyroid malignancy: a systematic review and meta-analysis

AIMS

Today, the color Doppler ultrasonography is used to further evaluate suspected malignant tumors. This study investigates the malignant thyroid nodules using color Doppler.

METHODS

After extracting true positive, false positive, false negative, and true negative among included studies, a quality was evaluated by the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (with 95% confidence interval) were found using a random effect model. Summary receiver operating characteristic curves (SROC) were used to assess relationship between sensitivity and specificity. The area under the curve of the SROC was calculated to estimate the performance of color Doppler ultrasound to distinguish malignant thyroid nodules. Our registration code in PROSPERO is CRD42018111198.

RESULTS

Of 1125 articles, 288 articles were selected for the further investigation. After excluding irrelevant and poor articles, 20 studies were included for the meta-analysis. According to a random effect model, the pooled sensitivity and specificity of color Doppler ultrasound to distinguish malignant thyroid nodules were estimated as 0.74 (95% CI 0.62-0.83; [Formula: see text]) and 0.70 (95% CI 0.56-0.81; [Formula: see text]), respectively. The SROC curve consists of representing the paired results for sensitivity and specificity. According to SROC, AUC = 0.78 (95% CI 0.74-0.81) is between 0.75 and 0.92, so that color Doppler ultrasound has a good accuracy.

CONCLUSION

Color Doppler is a valuable non-invasive method for evaluating thyroid nodules, and it is a high-sensitivity diagnostic tool for assessing thyroid nodules. Resistive index > 0.75 and a pattern III or more in color Doppler predicts malignant with the confidence. Due to its precision, cost-efficiency, easy access, and non-invasive nature, color Doppler should be included in the standard clinical protocol for the decision-making period and the treatment evaluation.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY, AND ASSOCIAZIONE MEDICI ENDOCRINOLOGI MEDICAL GUIDELINES FOR CLINICAL PRACTICE FOR THE DIAGNOSIS AND MANAGEMENT OF THYROID NODULES--2016 UPDATE

Thyroid nodules are detected in up to 50 to 60% of healthy subjects. Most nodules do not cause clinically significant symptoms, and as a result, the main challenge in their management is to rule out malignancy, with ultrasonography (US) and fine-needle aspiration (FNA) biopsy serving as diagnostic cornerstones. The key issues discussed in these guidelines are as follows: (1) US-based categorization of the malignancy risk and indications for US-guided FNA (henceforth, FNA), (2) cytologic classification of FNA samples, (3) the roles of immunocytochemistry and molecular testing applied to thyroid FNA, (4) therapeutic options, and (5) follow-up strategy. Thyroid nodule management during pregnancy and in children are also addressed. On the basis of US features, thyroid nodules may be categorized into 3 groups: low-, intermediate-and high-malignancy risk. FNA should be considered for nodules ≤10 mm diameter only when suspicious US signs are present, while nodules ≤5 mm should be monitored rather than biopsied. A classification scheme of 5 categories (nondiagnostic, benign, indeterminate, suspicious for malignancy, or malignant) is recommended for the cytologic report. Indeterminate lesions are further subdivided into 2 subclasses to more accurately stratify the risk of malignancy. At present, no single cytochemical or genetic marker can definitely rule out malignancy in indeterminate nodules. Nevertheless, these tools should be considered together with clinical data, US signs, elastographic pattern, or results of other imaging techniques to improve the management of these lesions. Most thyroid nodules do not require any treatment, and levothyroxine (LT4) suppressive therapy is not recommended. Percutaneous ethanol injection (PEI) should be the first-line treatment option for relapsing, benign cystic lesions, while US-guided thermal ablation treatments may be considered for solid or mixed symptomatic benign thyroid nodules. Surgery remains the treatment of choice for malignant or suspicious nodules. The present document updates previous guidelines released in 2006 and 2010 by the American Association of Clinical Endocrinologists (AACE), American College of Endocrinology (ACE) and Associazione Medici Endocrinologi (AME).

Contrast-enhanced ultrasound and real-time elastography in the differential diagnosis of malignant and benign thyroid nodules

The diagnostic value of contrast-enhanced ultrasound (CEUS) or real-time elastography (RTE) alone, as well as a combination of CEUS and RTE, in distinguishing benign from malignant thyroid nodules was investigated. Between August 2012 and June 2014, a total of 97 consecutive patients (50 male and 47 female patients; mean age, 48.6±12.4; age range, 27-70 years) with thyroid nodules referred for surgical treatment were examined by CEUS and RTE. The final diagnosis was obtained based on histological findings. Image analysis of the CEUS and RTE scans was performed. Considering the postoperative pathological results as the golden standard, a receiver operating characteristic (ROC) curve was constructed. Subsequently, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of CEUS alone, RTE alone and CEUS + RTE combination were calculated. Pathological examination showed 66 papillary carcinomas and 43 benign lesions, including 21 adenomas and 22 nodular goiters. The sensitivity, specificity, PPV, NPV and accuracy of CEUS were 81.82, 90.70, 93.10, 90.70 and 85.32%, respectively. In the case of RTE, the sensitivity, specificity, PPV, NPV and accuracy were 80.30, 88.37, 91.38, 88.37 and 83.49%, respectively. Furthermore, the combination of CEUS + RTE had a sensitivity of 95.45%, specificity of 95.35%, PPV of 96.92%, NPV of 95.35% and accuracy of 95.41%. Therefore, the CEUS + RTE combination showed a significantly higher sensitivity and specificity compared with CEUS or RTE alone (all P<0.05). Based on ROC analysis, the area under the curve (AUC) for CEUS, RTE and CEUS + RTE combination was 0.883, 0.863 and 0.959, respectively. The AUC of RTE alone was significantly lower compared with that of the CEUS + RTE combination. In conclusion, our results demonstrate that CEUS + RTE combination significantly increases the diagnostic performance for differential diagnosis of malignant and benign thyroid nodules compared with CEUS or RTE alone.

Quantitative Evaluation of Vascularity Using 2-D Power Doppler Ultrasonography May Not Identify Malignancy of the Thyroid

The purpose of this study was to evaluate the usefulness of a quantitative vascular index in predicting thyroid malignancy. A total of 1309 thyroid nodules in 1257 patients (mean age: 50.2 y, range: 18-83 y) were included. The vascularity pattern and vascular index (VI) measured by quantification software for each nodule were obtained from 2-D power Doppler ultrasonography (US). Gray-scale US + vascularity pattern was compared with gray-scale US + VI with respect to diagnostic performance. Of the 1309 thyroid nodules, 927 (70.8%) were benign and 382 (29.2%) were malignant. The area under the receiver operating characteristics curve (Az) for gray-scale US (0.82) was significantly higher than that for US combined with vascularity pattern (0.77) or VI (0.70, all p < 0.001). Quantified VIs were higher in benign nodules, but did not improve the performance of 2-D US in diagnosing thyroid malignancy.

Differentiation of benign and malignant thyroid nodules based on the proportion of sponge-like areas on ultrasonography: imaging-pathologic correlation

Purpose:

The purpose of this study was to determine whether it is possible to differentiate benign from malignant thyroid nodules according to the proportion of sponge-like appearance within the nodules.

Methods:

A total of 201 thyroid nodules containing sponge-like appearance from 195 patients (157 women and 38 men) were included this study. Each thyroid nodule was classified into one of three grades by real-time ultrasonography (US) based on the areas with a sponge-like appearance within nodule: grade I had sponge-like areas occupying <50%; grade II, between 50% and 75%; and grade III, >75%. We evaluated whether a correlation existed between these grades and cytopathologic diagnoses.

Results:

Of the 201 nodules, 196 were benign and five were malignant, and according to the US classification, 101 nodules were grade I, 45 were grade II, and 55 were grade III. Of the five malignant nodules, four were grade I, and one was grade II. No statistically significant difference was found in the rate of malignancy between grade III and grades I and II, due to insufficient statistical power. A sponge-like appearance was correlated with follicles filled with colloid and cholesterol granules in benign nodules and with papillary fronds around the dilated cystic spaces in malignant nodules.

Conclusion:

No malignancies were found in thyroid nodules with >75% sponge-like appearance. Due to the overall low incidence of malignancy and the limited number of patients, a statistically significant difference could not be found in the prevalence of malignancy depending on the proportion of sponge-like areas within the nodule.

Imaging findings of thyroidal sarcoma

From 1997 to 2013, 8849 patients with several disorders of the thyroid were treated in our surgical department. In nine patients (0.1%), primary thyroid sarcoma (PTS) was diagnosed. In eight patients, PTS manifested as a thyroid mass (range, 25-90 mm). In one case, a global enlargement of the thyroid was seen. Clinically, all patients presented with neck swelling. On ultrasound, PTS was predominantly hypoechoic. On computed tomography, the sarcomas were hypodense. On magnetic resonance imaging, PTS had inhomogeneous signal increase on T2-weighted images and signal decrease on T1-weighted images with inhomogeneous enhancement.

Development of a logistic regression formula for evaluation of subcentimeter thyroid nodules

OBJECTIVES

The purpose of this study was to build a logistic regression formula for ameliorating the diagnosis of subcentimeter thyroid nodules.

METHODS

The sonographic features of 889 subcentimeter nodules were reviewed retrospectively with reference of histologic results. The diagnostic performance of each feature was evaluated. Multivariate binary logistic regression was used to develop the formula for evaluation of subcentimeter nodules, and the cutoff value was decided for recommending biopsy.

RESULTS

The logistic regression formula was -0.029age - 2.063US1 - 0.812US2 + 1.781US3 + 1.627height-to-width ratio - 0.333 (for nonhypoechogenicity, US1 = 1; for hypoechogenicity, US1 = 0; for a well-circumscribed margin, US2 = 1 and US3 = 0; for a microlobulated margin, US2 = 0 and US3 = 1; and for an irregular margin, US2 = 0 and US3 = 0). The area under the receiver operating characteristic curve for the formula was 0.860. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the formula under the cutoff value of 0.284 were 90.9%, 54.0%, 66.4%, 85.6%, and 72.5%, respectively. With the use of the formula, 229 of 830 nodules could avoid surgery.

CONCLUSIONS

A logistic regression formula with a cutoff value could provide an objective and easy tool with effective diagnostic performance, which could improve diagnosis of subcentimeter thyroid nodules and reduce unnecessary biopsy, decreasing costs and patient discomfort.

Quantitative analysis of dynamic power Doppler sonograms for patients with thyroid nodules

To clarify and determine whether power Doppler sonograms are useful for the detection of malignant thyroid nodules, a computerized quantification method was used to evaluate the vascular density of a thyroid nodule in a prospective setting. Sonographic power Doppler images were collected in consecutive frames (45 frames of images), and a proprietary program (AmCAD-UV) was implemented using methods proposed in this article automatically calculated a quantified power Doppler vascular index (PDVI). The minimum PDVI value (PDVImin) was suggested as a measure of the vascular density of the nodule. The vascular densities of the peripheral and central areas of the nodule, referred to as central PDVImin and Ring PDVImin, respectively, were also evaluated. For 238 tumors (79 malignant and 159 benign) from 208 patients, all of the proposed indices of benign lesions were significantly higher than those of the malignant lesions. The area under the receiver operating characteristic curve (AUC) reaches 71% with the PDVImin. When the vascular patterns were further classified into intra-nodular and peripheral vascularity types, no vascularity type was observed significantly more frequently in malignant nodules than in benign nodules. These proposed computerized vascular indices provide a quantification method to objectively evaluate thyroid nodules and have potential as predictors of thyroid malignancy. The conventional vascular characterizations of malign nodules, that is, more vessels are observed in malignant nodules than in benign nodules, are shown to be unreliable in our study. Instead, a higher value of the quantified power Doppler vascular density was observed in benign nodules.

Tumor size and presence of calcifications on ultrasonography are pre-operative predictors of lymph node metastases in patients with papillary thyroid cancer

BACKGROUND AND OBJECTIVES

Lymph node metastases in papillary thyroid cancer (PTC) are common and their presence can significantly alter the treatment for patients with PTC. We therefore sought to identify pre-operative predictors of lymph node metastases in patients with PTC.

METHODS

A thyroid tumor database was queried to identify patients with a pre-operative diagnosis of PTC and underwent thyroidectomy between January 2006 and August 2009. One hundred and three patients who had a pre-operative ultrasound and had lymph nodes surgically resected were identified. Clinical factors and tumor ultrasound characteristics were recorded. The pre-operative ultrasound results, type of operation, and final pathology results were also recorded.

RESULTS

Of the 103 patients, 74 (72%) were women and 29 (28%) were men with an age range of 15-78 years (median age of 43). Of the ultrasound characteristics evaluated only calcifications (P = 0.007) and size (P = 0.003) were statistically associated with positive cervical lymph nodes. None of the other demographic or clinical factors were significantly associated with lymph node metastases.

CONCLUSIONS

Thyroid nodule size and presence of calcifications on ultrasound were found to have a statistically significant association with lymph node metastases in patients with PTC. This information could be used to guide the surgical management of these patients.

Advantages and disadvantages of 3D ultrasound of thyroid nodules including thin slice volume rendering

BACKGROUND

The purpose of this study was to assess the advantages and disadvantages of 3D gray-scale and power Doppler ultrasound, including thin slice volume rendering (TSVR), applied for evaluation of thyroid nodules.

METHODS

The retrospective evaluation by two observers of volumes of 71 thyroid nodules (55 benign, 16 cancers) was performed using a new TSVR technique. Dedicated 4D ultrasound scanner with an automatic 6-12 MHz 4D probe was used. Statistical analysis was performed with Stata v. 8.2.

RESULTS

Multiple logistic regression analysis demonstrated that independent risk factors of thyroid cancers identified by 3D ultrasound include: (a) ill-defined borders of the nodule on MPR presentation, (b) a lobulated shape of the nodule in the c-plane and (c) a density of central vessels in the nodule within the minimal or maximal ranges. Combination of features provided sensitivity 100% and specificity 60-69% for thyroid cancer.Calcification/microcalcification-like echogenic foci on 3D ultrasound proved not to be a risk factor of thyroid cancer.Storage of the 3D data of the whole nodules enabled subsequent evaluation of new parameters and with new rendering algorithms.

CONCLUSIONS

Our results indicate that 3D ultrasound is a practical and reproducible method for the evaluation of thyroid nodules. 3D ultrasound stores volumes comprising the whole lesion or organ. Future detailed evaluations of the data are possible, looking for features that were not fully appreciated at the time of collection or applying new algorithms for volume rendering in order to gain important information. Three-dimensional ultrasound data could be included in thyroid cancer databases. Further multicenter large scale studies are warranted.

Cystic thyroid nodules after aspiration mimicking malignancy: sonographic characteristics

OBJECTIVE

The purpose of our study was to provide sonographic findings of cystic nodules, which can mimic malignancies, after fine-needle aspiration (FNA) and to determine the differential points from malignancies.

METHODS

We retrospectively reviewed the sonographic findings of 33 lesions in 32 patients who had FNA for predominantly cystic nodules or cysts and showed suspicious findings during sonographic follow-up, as well as findings of 47 surgically confirmed papillary thyroid carcinomas (PTCs) in 45 consecutive patients. We evaluated the size, shape, presence of shadowing and a halo, margin, echogenicity, and presence of echogenic dots for each nodule. The final diagnosis of cystic nodules was confirmed by FNA, surgery, or follow-up sonography.

RESULTS

Of the 33 cystic lesions, 31 (94%) were adequate with benign results, and 2 (6%) were inadequate specimens at the initial FNA. There were no malignancies in the cystic nodules at follow-up. The average interval between the initial FNA and suspicious sonographic findings was 26 months (range, 1-92 months). The average size of the suspicious nodules was 0.8 cm (range, 0.3-1.8 cm). Cystic nodules after aspiration were similar to PTCs in their sonographic findings, but the former frequently showed shadowing and a halo (85% versus 21%; P < .0001). With further follow-up, 29 lesions (88%) showed additional decreases in size.

CONCLUSIONS

Benign cystic nodules after aspiration can have suspicious malignant features. However, shadowing and a halo associated with malignant features are characteristic findings of cystic nodule shrinkage. Awareness of these findings and correlation with the FNA history can aid in preventing unnecessary FNA.

Can vascularity at power Doppler US help predict thyroid malignancy?

PURPOSE

To retrospectively evaluate the diagnostic performance of power Doppler ultrasonography (US) in depicting vascularity and to determine whether the combination of vascularity and suspicious gray-scale US features is more useful in predicting thyroid malignancy than are gray-scale features alone.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective study, with waiver of informed consent. A total of 1083 thyroid nodules in 1024 patients (median age, 51 years; range, 16-83 years), consisting of 886 women (median age, 50 years; range, 16-83 years) and 138 men (median age, 53 years; range, 19-74 years), were included. Nodules with marked hypoechogenicity, noncircumscribed margins, microcalcifications, and taller-than-wide shape were classified as suspicious according to gray-scale US criteria. Vascularity was classified as none, peripheral, and intranodular. The diagnostic performance of gray-scale and power Doppler US features was compared and classified as follows: criterion 1, any single suspicious gray-scale US feature; criterion 2, addition of any vascularity as one of the suspicious features to criterion 1; criterion 3, addition of peripheral vascularity to criterion 1; criterion 4, addition of intranodular vascularity to criterion 1; criterion 5, addition of no vascularity to criterion 1; criterion 6, American Association of Clinical Endocrinologists and Associazione Medici Endocrinology guidelines--all hypoechoic nodules with at least one of the following US features: irregular margins, intranodular vascular spots, taller-than-wide shape, or microcalcifications.

RESULTS

Of 1083 nodules, 814 were benign and 269 were malignant. Intranodular vascularity was frequently seen in benign nodules and no vascularity was more frequent in malignant nodules (P < .0001, respectively). The area under the receiver operating characteristic curve (A(z)) of criterion 1 was superior (A(z) = 0.851) to that of criteria 2 (A(z) = 0.634), 3 (A(z) = 0.752), 4 (A(z) = 0.733), 5 (A(z) = 0.718), and 6 (A(z) = 0.806) (P < .0001).

CONCLUSION

Vascularity itself or a combination of vascularity and gray-scale US features was not as useful as the use of suspicious gray-scale US features alone for predicting thyroid malignancy.

Hürthle cell neoplasm: correlation of gray-scale and power Doppler sonographic findings with gross pathology

BACKGROUND

To describe gray-scale and power Doppler (PD) sonographic (US) findings of Hürthle cell neoplasms (HCNs) of the thyroid gland, and to determine if there is any correlation between US and gross pathologic features.

METHOD

This retrospective study included 30 pathologically proven HCNs in 30 subjects who underwent preoperative gray-scale and PD US examinations. The size, shape, margin, echogenicity, echotexture, presence or absence of cystic change, calcifications and halo sign, and vascularity at PD US were evaluated.

RESULT

The longest diameter of HCNs ranged from 12 mm to 63 mm. The shape and margins of the mass were ovoid and smooth, respectively, in all cases. The echogenicity was hypoechoic, isoechoic, hyperechoic, or mixed in 43.3%, 33.3%, 10.0%, and 13.3%, respectively. The echotexture was heterogeneous in 73.3% and homogeneous in 26.7%. Cystic change was present in 56.7% and involved less than 25% of the volume of the mass in 50.0% and 26-50% of the volume in 6.7%. Coarse calcifications were present in 20.0%. Halo sign was present in all cases. The vascularity was combined peri- and intranodular in all cases: predominantly intranodular in 50.0%, predominantly perinodular in 46.7%, and of the "inferno" type in 3.3%. All HCNs were encapsulated on gross pathologic examination.

CONCLUSION

Although many of the US features we observed were nonspecific, HCNs tend to have a halo sign and combined peri- and intranodular vascularity on US, which raises the possibility of an association. The US halo sign corresponds to tumor capsule ongross pathologic examination.

A proposal for a thyroid imaging reporting and data system for ultrasound features of thyroid carcinoma

BACKGROUND

Several thyroid ultrasound (TUS) findings have been associated with an increased risk for thyroid cancer; however, there is no consensus as to the format and style for reporting the results of TUS. The objective of this study was to discover the features indicative of malignancy in thyroid nodules based on TUS, generate an equation using these features that would be predictive of malignancy in thyroid nodules, and stratify the results of this equation into TUS categories reflecting the probability of malignancy.

METHODS

We obtained odds ratios of TUS findings indicative of malignancy and probability of malignancy for each nodule as determined by logistic regression analysis of ultrasound (US) findings in 1694 patients who had US-guided fine-needle aspiration biopsy. We then generated an equation to predict the probability of malignancy based on TUS and developed categories ranging from lowest to highest probability of malignancy. We evaluated the reliability of this equation and the categories using cytology and histopathology information regarding malignancy in the thyroid nodules.

RESULTS

We characterized 12 aspects of thyroid nodules as seen on TUS and developed an equation to predict P(us), the probability of a nodule being malignant based on these US findings. The equation was P(us) = 1/(1 + e(-z)), where e is the mathematical constant 2.71828 and z is the logit of malignant thyroid nodule. P(us) was stratified into five categories based on the probability of a nodule being malignant as indicated by the findings (TUS 1, benign; TUS 2, probably benign; TUS 3, indeterminate; TUS 4, probably malignant; TUS 5, malignant). There was a significant correlation between the cytological category and the TUS 1 through TUS 5 categories (r = 0.491, p < 0.001).

CONCLUSIONS

We propose an equation to predict the probability of malignancy in thyroid nodules based on 12 features of thyroid nodules as noted on TUS. This equation, and the stratification of its results into categories, should be useful in reporting the findings of US for thyroid nodules and in guiding management decisions.

Sonography and fine-needle aspiration biopsy in the diagnosis of benign versus malignant nodules in patients with autoimmune thyroiditis

PURPOSE

To correlate sonographic (US) characteristics and results of fine-needle aspiration biopsy (FNAB) of thyroid nodules in autoimmune thyroiditis (AT) with surgical pathological findings.

METHOD

Forty AT patients with 40 nodular lesions were analyzed retrospectively. Five sonographic characteristics were recorded for each nodule: diameter, echogenicity, microcalcification, halo sign, and margin. Preoperative sonograms and FNAB results were compared with postoperative histopathological findings.

RESULT

Twenty-four of the 40 nodules were malignant, including 20 papillary carcinomas, 3 follicular carcinomas, and 1 medullary carcinoma. Of the 16 benign nodules, 8 were nodular hyperplasia, 6 lymphocytic thyroiditis, and 1 each follicular adenoma and Hürthle cell adenoma. The only US parameter that was significant in malignant vs. benign nodules was the presence of poorly defined margins. Based on preoperative cytology, 22 of the 23 malignant nodules were correctly diagnosed, and 10 of the 14 benign nodules were correctly identified. The positive predictive value was 78.6%, and the negative predictive value was 93.7%.

CONCLUSION

No single US parameter can predict thyroid malignancy in patients with AT. A combination of US and FNAB provides the most sensitive and specific approach available preoperatively.

Partially cystic thyroid nodules on ultrasound: probability of malignancy and sonographic differentiation

BACKGROUND

Thyroid nodules are very common and a large portion are mixed echoic, with both solid and cystic areas. There are few studies regarding the reliability of ultrasonographic criteria for evaluating solid nodules as they apply to mixed echoic nodules. The object of this study was to evaluate the frequency of malignancy in mixed echoic thyroid nodules and ascertain the ultrasound findings that help distinguish benign from malignant nodules.

METHODS

Among 1056 thyroid nodules undergoing ultrasound with fine-needle aspiration (FNA) biopsy, 392 nodules (37.1%) were mixed echoic. From this group of 392, the nodules that were read as benign or malignant on histopathology examination after surgery and the nodules that were not resected but were considered to be benign or malignant on cytology were analyzed for their ultrasonographic features. The nodules were divided into the following three groups. Group 1 (n = 93) included nodules in which the solid portion was <50%; group 2 (n = 216) comprised nodules in which the solid portion was >or=50%; and group 3 (n = 26) included mixed echoic (spongy) nodules. We also analyzed features of the solid portion of the nodule, namely, its position (eccentric or not), shape, margin, and echogenicity, and whether there were micro/macrocalcifications.

RESULTS

In the FNA sample, 52 nodules were inadequate for cytological diagnosis, but the remaining 340 (86.7%) were adequate. Eighteen of the nodules were malignant and 317 were benign, yielding a malignancy rate of 5.4%. By group, the malignancy rate was 2.2% (2/93) in group 1, 7.4% (16/216) in group 2, and 0% (0/26) in group 3. There were more malignancies in group 2 than the other groups (p = 0.040). Among sonographic findings, eccentric placement (p = 0.007) and the presence of microcalcifications (p < 0.001) were significantly correlated with malignancy.

CONCLUSIONS

About 5% of partially cystic nodules in our series were malignant. When more than 50% of the nodule is solid and the solid portion of the nodule is eccentric, the risk of malignancy is greater. As has been noted for completely solid nodules, microcalcifications are associated with an increased risk of malignancy.

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.