Diagnostic Performance of Margin Features in Thyroid Nodules in Prediction of Malignancy

OBJECTIVE

The purpose of this study was to evaluate thyroid nodule margins for specific morphologic features and determine the diagnostic performance of these features in differentiating papillary carcinoma from benign thyroid nodules.

MATERIALS AND METHODS

Nodules measuring 1-3 cm in largest diameter that had been evaluated with high-resolution ultrasound (12-18 MHz) and ultrasound-guided biopsy with definitive pathologic diagnosis were analyzed. Three blinded board-certified readers evaluated high-resolution images of each nodule for jagged edges, lobulated borders, and curved borders along their margins. Reader interpretations were correlated with the pathologic diagnosis to determine the diagnostic performance of each feature. A board-certified pathologist analyzed 10 randomly selected nodules with jagged edges by slide review to evaluate for structural correlation with the imaging finding.

RESULTS

The diagnostic performance of jagged edges in papillary carcinoma of the thyroid was 67.4% sensitive and 78.3% specific (odds ratio, 7.44; p < 0.001) for malignancy. Jagged edges correlated with infiltrative variant expansion at slide review. Lobulated borders had sensitivity of 76.1% and specificity of 60.9% for papillary carcinoma (odds ratio, 4.95; p = 0.001) for malignancy. Curved borders were not a significant predictor of papillary carcinoma.

CONCLUSION

Jagged edges and lobulated borders of thyroid nodule margins are statistically significant predictors of papillary carcinoma of the thyroid. Jagged edges correlate with infiltrative-type expansion and may be useful predictors of more aggressive papillary carcinomas.

The utility of ultrasound elastography and MicroPure imaging in the differentiation of benign and malignant thyroid nodules

OBJECTIVE

The aim of this study was to evaluate the utility of ultrasound elastography and MicroPure imaging in the differential diagnosis of benign and malignant thyroid nodules.

SUBJECTS AND METHODS

A total of 74 consecutive patients (65 women and nine men; age range, 21-80 years; mean [± SD] age, 51 ± 12.7 years) with thyroid nodules, who were referred for fine-needle aspiration biopsy by endocrinology or general surgery clinics, were prospectively examined using B-mode ultrasound, ultrasound elastography, and MicroPure imaging. The strain value ratio (strain index) of thyroid nodules was calculated. Patients with malignant or intermediate fine-needle aspiration biopsy results underwent thyroid surgery.

RESULTS

Using MicroPure imaging, 17 of 65 benign thyroid nodules (26.6%) and three of nine malignant thyroid nodules (33.3%) were found to contain microcalcifications. The sensitivity, specificity, negative predictive value, positive predictive value, and the accuracy rate of MicroPure imaging were 42.9%, 80.6%, 93.1%, 18.8%, and 77%, respectively. By using receiver operating characteristic analysis, the best cutoff point (2.31) was computed (area under the curve, 0.87; p < 0.001). The sensitivity, specificity, negative predictive value, positive predictive value and accuracy rate of the strain index values were 85.7%, 82.1%, 98.2%, 33.3%, and 82.4%, respectively, when the best cutoff point of 2.31 was used (p = 0.001). The p value (x = malign) was 0.96 for a strain index value higher than 2.31.

CONCLUSION

This preliminary study indicated that ultrasound elastography and MicroPure imaging can be used for the differentiation of benign and malignant thyroid nodules.

Compressibility of thyroid masses: a sonographic sign differentiating benign from malignant lesions?

OBJECTIVE

The purpose of this study was to assess the manual compressibility of thyroid masses with an ultrasound probe and to determine whether this ultrasound feature can be used to differentiate benign from malignant thyroid lesions.

SUBJECTS AND METHODS

We prospectively compared images obtained during compression with an ultrasound probe and noncompressed ultrasound images of 180 pathologically proven thyroid masses (51 malignant, 129 benign) smaller than 2 cm in 169 patients (127 women, 42 men; mean age, 51.2 years). The size (anteroposterior and transverse dimensions) and shape (ratio of anteroposterior to transverse dimension) of the selected lesions were measured on both noncompressed and compressed ultrasound images at a computer workstation, and the compressibility (anteroposterior-to-transverse ratio on noncompressed images minus anteroposterior-to-transverse ratio on compressed images) was calculated. Compressibility was analyzed to determine its association with histopathologic results (benign versus malignant) and the characteristics of the thyroid mass (involved lobe, location in lobe, halo, and composition). The area under the receiver operating characteristic curve was used as an indicator of performance.

RESULTS

The mean anteroposterior-to-transverse ratio of a thyroid mass on compressed ultrasound images was significantly lower than that on noncompressed images (0.78 ± 0.28 vs 0.92 ± 0.30; p < 0.001). The compressibility of masses was greater for benign than for malignant lesions (0.19 ± 0.16 vs 0.05 ± 0.12; p < 0.001). No statistically significant association was identified between compressibility and other characteristics of a lesion. The area under the receiver operating characteristic curve for compressibility of thyroid masses was 0.78. On the basis of a cutoff value for malignancy of compressibility less than 0.10, the sensitivity, specificity, and accuracy were 72.5%, 72.9%, and 72.8%.

CONCLUSION

Compressibility with an ultrasound probe is a useful criterion for differentiating benign from malignant lesions of the thyroid.

Implementation of evidence-based guidelines for thyroid nodule biopsy: a model for establishment of practice standards

OBJECTIVE

Multiple studies have defined criteria for the selection of thyroid nodules for biopsy. No set of criteria is sufficiently sensitive and specific. The aim of this study is to develop a method for assessing consistency of practice in an ultrasound group and to determine whether a 5-point malignancy rating scale can be used to select patients for biopsy.

MATERIALS AND METHODS

One hundred one nodules (50 benign and 51 malignant) were selected from a thyroid biopsy database. Seven radiologists were educated on evidence-based criteria used to select nodules for biopsy. Using this information, readers graded the likelihood of malignancy using a 5-point malignancy rating scale, where 1 equals the lowest probability of malignancy and 5 equals the highest probability of malignancy, on the basis of overall impression of sonographic findings. Interobserver agreement on biopsy recommendation, reader sensitivity, specificity, and accuracy were determined.

RESULTS

The sensitivity and specificity of biopsy recommendation were 96.1% and 52%, respectively. The misclassification rate was 25.7%, and accuracy was 74.3%. Interobserver agreement on biopsy recommendation was fair to substantial (κ, 0.38-0.69). The proportion of agreement was excellent for malignant nodules (0.88-1.0). The risk of malignancy increased with increasing malignancy rating: 4.3% of nodules with a malignancy rating of 1 were malignant versus 93.4% of those assigned a rating of 5.

CONCLUSION

Our study illustrates a method to evaluate the standard of practice for thyroid nodule assessment among radiologists within an ultrasound group. Application of a 5-point malignancy rating scale to select nodules for biopsy is feasible and shows good diagnostic accuracy.

Pattern recognition of benign nodules at ultrasound of the thyroid: which nodules can be left alone?

OBJECTIVE

The purpose of this study was to evaluate morphologic features predictive of benign thyroid nodules.

MATERIALS AND METHODS

From a registry of the records of 1,232 fine-needle aspiration biopsies performed jointly by the cytology and radiology departments at a single institution between 2005 and 2007, the cases of 650 patients were identified for whom both a pathology report and ultrasound images were available. From the alphabetized list generated, the first 500 nodules were reviewed. We analyzed the accuracy of individual sonographic features and of 10 discrete recognizable morphologic patterns in the prediction of benign histologic findings.

RESULTS

We found that grouping of thyroid nodules into reproducible patterns of morphology, or pattern recognition, rather than analysis of individual sonographic features, was extremely accurate in the identification of benign nodules. Four specific patterns were identified: spongiform configuration, cyst with colloid clot, giraffe pattern, and diffuse hyperechogenicity, which had a 100% specificity for benignity. In our series, identification of nodules with one of these four patterns could have obviated more than 60% of thyroid biopsies.

CONCLUSION

Recognition of specific morphologic patterns is an accurate method of identifying benign thyroid nodules that do not require cytologic evaluation. Use of this approach may substantially decrease the number of unnecessary biopsy procedures.

Differences in sonographic conspicuity according to papillary thyroid cancer subtype: results of the Ukrainian-American cohort study after the Chornobyl accident

OBJECTIVE

Over time, the histology of papillary thyroid cancers detected in a repeatedly screened population exposed to radiation at Chornobyl (Chernobyl) has shifted from a more aggressive subtype toward less aggressive subtypes. This change may reflect biologic behavior but could also be influenced by the detectability of different subtypes. The study objective was to identify whether there is any relationship between the conspicuity of sonographically detected papillary cancers and histologic subtype.

MATERIALS AND METHODS

Sonographic images of 84 papillary cancers occurring in young people exposed to radiation at Chornobyl were each given a conspicuity score using a subjective 1-5 scale by four independent expert readers blinded to histologic subtype. The effects of tumor subtype, tumor encapsulation, reader, machine type, and nodule size on sonographic conspicuity were determined using analysis of variance and Spearman correlations.

RESULTS

Cancer subtype was related to sonographic conspicuity (p < 0.01). The relatively aggressive solid subtype of papillary carcinoma was more conspicuous than the papillary, follicular, and mixed subtypes (p < 0.05). The other subtypes did not differ significantly from each other in conspicuity. Conspicuity was not significantly related to nodule size, degree of encapsulation, age and sex of the subject, or machine type. Although the mean conspicuity score for each reader differed significantly, reliability of conspicuity judgments across readers was fair.

CONCLUSION

In subjects exposed to radiation from the Chornobyl accident, the solid subtype of papillary carcinoma appears to be more conspicuous on sonography than the other subtypes. Therefore, the change in subtype observed over time in this repeatedly screened population may be influenced by differences in nodule conspicuity.

Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology

OBJECTIVE

The purpose of our study was to determine the prevalence of malignancy in incidental abnormalities of the thyroid gland detected on CT and to determine the relative accuracy of characterizing these abnormalities on CT as compared with sonography and pathology.

MATERIALS AND METHODS

We searched our department's computerized clinical database for all thoracic and cervical CT scans in which a new abnormality was incidentally identified in the thyroid gland from 1998-2001. Two hundred thirty patients with abnormal findings in the gland on CT subsequently underwent thyroid sonography, and 118 of the 230 patients underwent a diagnostic biopsy or resection. CT and sonographic images were directly reviewed to identify imaging features of each thyroid abnormality, including the location, size, appearance, and presence or absence of calcifications. Associations were evaluated using Fisher's exact test of significance and the Student's t test. The overall rate of malignant and potentially malignant lesions among these incidental abnormalities of the thyroid gland was calculated.

RESULTS

CT findings matched the sonographic characterization in 122 patients (53.0%), correctly identified the dominant nodule but missed multinodularity in 69 (30.0%) patients, and underestimated the number of nodules in 24 (10.4%) patients. CT overestimated the number of nodules in 5 (2.2%) patients and was false-positive for lesions in 10 patients (4.3%). Ninety-one patients with a single or dominant nodule on CT had pathologic correlation: 7 nodules were malignant, 17 showed malignant potential, and 67 were benign. Of 27 patients with multinodular or enlarged thyroid glands on CT and histopathologic correlation, 2 lesions were malignant and 25 benign. The presence of punctate calcifications on CT significantly correlated to the presence of microcalcifications on sonography (p < 0.02). Benign nodules were significantly smaller (mean, 2.16 +/- 1.01 cm; range, 0.6-4.5 cm) than malignant and potentially malignant nodules (mean, 2.79 +/- 0.99 cm; range, 0.7-4.6 cm) (p = 0.01). Patients 35 years or younger who had a thyroid lesion on CT were more likely to have malignancy (p < 0.01). Overall, among incidentally detected lesions of the thyroid gland, there was at least a 3.9% rate of malignancy (95% CI: 1.8-7.3%) and 7.4% rate of malignant potential (95% CI: 4.4-11.6%).

CONCLUSION

There is at least an 11.3% prevalence of malignant or potentially malignant lesions among incidental thyroid abnormalities detected on CT. Patients 35 years or younger who have incidental abnormalities have a significantly greater rate of malignancy. No CT feature reliably distinguishes benign from malignant lesions in the thyroid gland. CT underestimates the number of nodules relative to sonography, which suggests that sonography is a useful adjunctive test after the incidental detection of a thyroid abnormality on CT.