Diagnosis of Thyroid Cancer in Children: Value of Gray-Scale and Power Doppler US

Frequency of undetected thyroid nodules in a large I-131-exposed population repeatedly screened by ultrasonography: results from the Ukrainian-American cohort study of thyroid cancer and other thyroid diseases following the Chornobyl accident

BACKGROUND

Imperfect detection on screening tests can lead to erroneous conclusions about the natural history of thyroid nodules following radiation exposure. Our objective was to assess in a repeatedly screened I-131-exposed population the frequency with which a thyroid nodule could be retrospectively identified on ultrasonography studies preceding the one on which it was initially detected.

METHODS

A cohort of over 13,000 young people exposed to fallout from Chornobyl underwent ultrasonography screening at 2-year intervals from 1998 to 2007. The study group consisted of screening examinations on which a thyroid nodule was detected following one or more prior negative examinations. In the study group there were 48 cancers and 92 benign nodules. For each of these 140 index studies a comparison set was created containing all available prior studies plus (to test for bias) negative studies from control subjects. While viewing the index study, three independent reviewers scored the comparison studies for the presence and size of a preexisting nodule. Detection rates were compared for true priors versus controls, for cancer versus benign, and for histologic subtypes of papillary carcinoma.

RESULTS

A preexisting nodule was identified by at least one reviewer in 24.0% of the true prior versus 8.3% of the controls and by all three reviewers in 11% versus 1% (Fisher's exact test, p < 0.0001). There was no significant difference in detection rates between cancers and benign nodules (22.4% vs. 24.7%, p = 0.411). There was no correlation between time from prior to index study and change in nodule size for either malignant or benign nodules (r = 0.01, NS). There were no differences in detection rates or size among papillary cancer subtypes. Reviewers could not distinguish between true priors and controls.

CONCLUSIONS

These findings, showing significant rates of undetected benign and malignant nodules and no evidence for rapid growth, suggest that conclusions drawn from screening studies about the frequency of late-developing, rapidly growing thyroid nodules following radiation exposure should be interpreted with caution.

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.

[Comparison of color Doppler-evaluated thyroid nodule classifications as described by Lagalla and Chammas]

OBJECTIVE

Evaluate the vascularization classification of thyroid nodules with color Doppler ultrasonography described by Lagalla and cols. and Chammas and cols.

METHODS

A total of 265 thyroid nodules were studied with color Doppler and cytopathology.

RESULTS

In the diagnosis of nodules with malignant cytopathology, Chammas's IV and V patterns showed sensibility of 16.7%, specificity of 97.6%, positive predictive value of 33.3%, negative predictive value of 94.1% and accuracy of 92.1%; Lagalla's III pattern showed sensibility of 44.4%, specificity of 19.4%, positive predictive value of 3.9%, negative predictive value of 82.8% and accuracy of 21.1%.

CONCLUSION

Lagalla's classification showed low sensibility and accuracy in the detection of nodules with malignant cytopathology, while Chammas's classification showed high accuracy, however, low sensibility. Color Doppler was also insufficient to substitute the small needle punction and the cytopathologic study in the diagnosis of malignant thyroid nodules.

Imaging 'the lost tribe': a review of adolescent cancer imaging. Part 1

Although a small proportion of all cancer registrations, malignancy in adolescence and young adulthood remains the most common natural cause of death in this age group. Advances in the management and outcomes of childhood cancer have not been matched within the adolescent population, with increasing incidence and poorer survival seen amongst teenagers with cancer compared with other populations. There have been increasing moves towards specific adolescent oncology centres, with the aim of centralising expertise, however, ‘adolescent imaging’ does not exist as a speciality in the same way that paediatric imaging does, with responsibility for imaging adolescent patients sometimes falling to paediatric radiologists and sometimes to ‘adult’ radiologists, usually with a specific interest in a tumour type or body system. In this article, imaging of the more common malignancies, encountered in adolescent patients is reviewed. Complications of treatment are reviewed in another article to give an overview of adolescent oncology imaging practice.

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.

The usual ultrasonographic features of thyroid cancer are less frequent in small tumors that develop after a long latent period after the Chernobyl radiation release accident

BACKGROUND

The Chernobyl accident resulted in an unprecedented number of radiation-induced thyroid cancers in young individuals as detected by national and international screening programs. The vast majority of thyroid malignancies were papillary carcinomas that, despite being similar by histopathology, displayed large variability in clinical course. The correlations between ultrasound (US) and clinicopathological features in young patients with radiation-induced thyroid cancer, however, have not been well studied. Because of the importance of US for deciding which subjects should have fine-needle aspiration biopsy, we assessed the US features of papillary thyroid carcinoma in patients exposed to Chernobyl fallouts.

DESIGN

We performed a retrospective multivariate logistic regression analysis of US features, clinicopathological data, and the latency period between radiation exposure and the diagnosis of cancer in 94 patients who were 10.6-34.3 years old (16.5 +/- 6.2, mean +/- standard deviation) at the time of diagnosis and 0.1-18.0 years old (5.6 +/- 4.2) at the time of the Chernobyl accident.

RESULTS

Nodules greater than 10 mm were associated with the higher frequency of irregular margins (p = 0.001), longer period of latency (p = 0.016), and bilateral lymph node involvement (p = 0.025). Irregular tumor margins correlated with the shorter period of latency (p = 0.009) and unilateral nodal disease (p = 0.010). Hypoechoic nodules were observed more frequently in female patients (p = 0.012), in the absence of halo (p = 0.003) or calcifications (p = 0.005). Hypoechogenicity also correlated with the shorter latency (p = 0.015) and younger age of patients (p = 0.048).

CONCLUSIONS

Irregular nodule margins, a usual sign of malignancy, are less useful in detecting thyroid cancers in radiation-exposed patients with tumors less than 10 mm. Thyroid cancers that are detected after longer latent periods display less of the US features characteristic of a malignant process, while benign US features are observed more frequently. Therefore, we recommend fine-needle aspiration biopsy to ensure early diagnosis of thyroid cancer for patients with a history of radiation exposure, even if their nodules are less than 10 mm.

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.

[The role of radiologists in the management of thyroid nodules]

We review the different techniques in the diagnostic of thyroid nodule. The ultrasound and, especially, sonographically guided fine-needle aspiration (US-FNA), are the most accurate diagnostics tests to achieve a correct diagnosis of thyroid nodule, which is only done better by the surgery treatment and the pathology study of all lesion. We review the situations in which US-FNA is necessary and the different diagnostic and therapeutics options. Finally, we propose algorithms for the management of a solitary thyroid nodule, multinodular goiter and casually discovered nodule.

FAIR true-FISP perfusion imaging of the thyroid gland

PURPOSE

To evaluate the feasibility of quantitative perfusion MRI of the thyroid gland using an arterial spin labeling (ASL) method.

MATERIALS AND METHODS

An ASL technique with flow-sensitive alternating inversion-recovery (FAIR) spin preparation and a true fast imaging in the steady state (TrueFISP) signal readout strategy was implemented on a 1.5T whole-body unit. Anatomical and perfusion imaging of the thyroid gland was performed in eight healthy volunteers and one patient with functioning adenoma. Quantitative perfusion maps were calculated using the extended Bloch equations.

RESULTS

In all subjects the perfusion images showed diagnostic image quality. The mean examination time was 24 minutes for multiplanar perfusion imaging of the entire thyroid gland. Individual perfusion values ranged between 341 +/- 91 and 640 +/- 90 mL/100 g/minute, with a mean perfusion of 461 +/- 90 mL/100 g/minute. The functioning adenoma showed markedly reduced perfusion compared to normal thyroidal parenchyma. No perfusion was noticeable inside four detected thyroid cysts.

CONCLUSION

Quantitative ASL perfusion imaging of the thyroid gland using a FAIR-TrueFISP sequence leads to perfusion maps that may provide important information for assessing thyroid gland pathologies and monitoring therapeutic treatment.

Palpable pediatric thyroid abnormalities - diagnostic pitfalls necessitate a high index of clinical suspicion: a case report

A 12-year-old girl presented with a 4 year history of an enlarged, firm thyroid gland. On exam, her thyroid was firm and fixed and an enlarged cervical lymph node was palpable as well. Though a thyroid ultrasound prior to referral was read as thyroiditis, clinical suspicion for thyroid carcinoma mandated continued investigation. The diagnosis of papillary thyroid cancer was established and her workup revealed lymph node metastases as well as a tremendous burden of pulmonary metastases. Pediatric thyroid cancer is extremely rare, but often presents with aggressive disease. Palpable thyroid abnormalities in an individual under 20-years-old should be viewed with suspicion and should be thoroughly investigated to rule out malignancy even in the face of negative diagnostic procedures. Though pediatric papillary thyroid cancer often presents with loco-regional and even distant metastatic disease, mortality rates in follow-up for as long as 20 years are very favorable.

Quantitative analysis of tumor vascularity in benign and malignant solid thyroid nodules

OBJECTIVE

The purpose of our study was to analyze the accuracy of quantitative analysis of tumor vascularity on power Doppler sonograms in differentiating malignant and benign solid thyroid nodules using tumor histologic evaluation as the reference standard. Methods. Eighty-six solid thyroid tumors (46 malignant and 40 benign) in 56 consecutive patients (mean age +/- SD, 53.1 +/- 11.6 years; 12 male and 44 female) referred for the surgical treatment were included in our study. Visual and qualitative analysis of patterns of nodule vascularity was performed for all tumors. Quantification of the power Doppler sonograms was performed with normalized and weighted vascular indices (VIs). The accuracy of sonographic criteria for thyroid cancer was evaluated with univariate analysis. Results. Among benign thyroid tumors, there was a statistically significant increase in the levels of intranodular vascularization with an increase in tumor size (P < .001). In all tumors, increased intranodular vascularization showed 65.2% sensitivity, 52.5% specificity, and 58.9% overall accuracy in differentiation between benign and malignant thyroid lesions. In tumors smaller than 2 cm, it had 65.5% sensitivity, 85.7% specificity, and 72.1% overall accuracy. Quantitative analysis of tumor vascularity significantly overperformed visual analysis of power Doppler patterns (P < .05). Among thyroid lesions with diameters of less than 2 cm, a normalized VI of greater than 0.14 had 72.4% sensitivity, 100% specificity, and 86.2% overall accuracy. A weighted VI of greater than 0.24 showed compatible results, with 69.0% sensitivity, 100% specificity, and 84.5% overall accuracy.

CONCLUSIONS

Our study indicates that in small thyroid nodules, quantitative analysis of tumor vascularity has benefits over visual inspection and can be useful in differentiation between benign and malignant thyroid tumors.

Cervical lymph node metastases: diagnosis at sonoelastography--initial experience

PURPOSE

To prospectively estimate the accuracy of sonoelastography in the differentiation of benign and metastatic cervical lymph nodes (LNs) in patients suspected of having thyroid or hypopharyngeal cancer, with histologic nodal findings as the reference standard.

MATERIALS AND METHODS

The study protocol was approved by the hospital review board; each patient gave written informed consent. One hundred forty-one peripheral neck LNs (60 metastatic, 81 metastasis free) in 43 consecutive patients (22 men, 21 women; mean age, 58 years +/- 13 [standard deviation]) were examined. Patients referred for surgical treatment of suspected thyroid or hypopharyngeal cancer were examined with gray-scale ultrasonography (US), power Doppler US, and sonoelastography. At gray-scale and power Doppler US, the following LN characteristics were evaluated: short-axis diameter, short-to-long-axis diameter ratio, echogenicity, calcifications, and vascularity. A four-point rating scale was used to evaluate the US elastograms for LN visibility, relative brightness, margin regularity, and margin definition. In addition, strains of LN and surrounding neck muscles were measured on elastograms, and the muscle-to-LN strain ratio--that is, the strain index-was calculated. The diagnostic potential of the examined criteria for metastatic involvement was evaluated with univariate analysis and multivariate generalized estimating equation (GEE) regression. P < .05 indicated statistical significance.

RESULTS

A strain index greater than 1.5 had high utility in metastatic LN classification, with 98% specificity, 85% sensitivity, and 92% overall accuracy. These results were significantly better than those obtained by using the best gray-scale criterion--that is, a short-to-long-axis diameter ratio greater than 0.5-which had 81% specificity, 75% sensitivity, and 79% overall accuracy.

CONCLUSION

Sonoelastography had high accuracy (92%) in the differentiation of benign and metastatic cervical LNs in patients suspected of having thyroid or hypopharyngeal cancer.

Thyroid disease in the pediatric patient: emphasizing imaging with sonography

Thyroid disease does occur in the pediatric patient, and imaging plays an important role in its evaluation. A review is presented of normal development of the thyroid gland, the technique and indications for thyroid sonography, and key imaging features of congenital thyroid disorders (ectopic or absent thyroid, infantile goiter, thyroglossal duct remnants), benign thyroid masses (follicular adenoma, degenerative nodules, colloid and thyroid cysts), malignant masses (follicular, papillary and medullary carcinoma) and diffuse thyroid disease (acute bacterial thyroiditis, Hashimoto's thyroiditis, Grave's disease).

A novel thyroid phantom for ultrasound volumetry: determination of intraobserver and interobserver variability

A novel thyroid ultrasound phantom with tissue-equivalent characteristics was designed consisting of two lobes with three lesions each. One set of lesions is manufactured with a -5 dB echo difference to the surrounding tissue, the other with -10 dB. This phantom was used as a standardized measuring object for reproducibility of two-dimensional and three-dimensional ultrasound volumetry and for an interobserver and intraobserver variability study. For the variability study, nine experienced physicians scanned all specimen three times. Each time the volumes were calculated using the ellipsoid method. A three-dimensional ultrasound scan of each specimen was performed to evaluate all volumes by multiplanar volume approximation. The results of these volume data were compared to the known true volumes. The interobserver variability ranged from -13.4% to 11.9% (median, 0.7%); the intraobserver variability from -9.1% to 16.4% (median, 3.6%). The systematic error as calculated from the total mean of all specimens is 0.5% for the interobserver variability and 4.1% for the intraobserver variability. The phantom can be used for training purposes, to improve the skills of the examining physicians by simulating real thyroid morphology, to provide a standardized reference object for long-term quality control of conventional ultrasound scanners, and the determination of the accuracy and reproducibility of volumetry using three-dimensional ultrasound systems.

Gray-scale three-dimensional sonography of thyroid nodules: feasibility of the method and preliminary studies

The aim of the study was differential evaluation of new and classical sonographic features of benign thyroid nodules and thyroid cancer with three-dimensional gray-scale sonography and evaluation of the effectiveness of the thin-slice surface rendered images in comparison with multiplanar reformation (MPR) presentation. Fifty-four thyroid nodules were interactively evaluated with thin-slice smooth surface rendering: shape in the c-plane (parallel to the probe) and evaluation of echogenicity, margins and calcification/microcalcification-like echogenic foci in the a-plane (plane of the probe). Evaluation of the level of agreement in readers' interpretation and between sonographic techniques was performed using the kappa statistic. Surface rendering permitted visualization of the shape of the nodule in the c-plane in all cases, in contrast to only up to 48% of cases in MPR evaluation. Lobulated nodule shape in the c-plane was 82-100% sensitive and 47-53% specific in diagnosis of carcinoma. Surface rendered images showed more calcification/microcalcification-like echogenic foci than MPR ones. The level of agreement between the observers in the evaluation of features of thyroid nodules and the agreement between features of thyroid nodules on MPR and surface-rendered images showed at least moderate reproducibility (kappa>or=0.41). Three-dimensional thin-slice surface rendering sonography appears to be a feasible and effective method for thyroid nodule evaluation.

Elastic moduli of thyroid tissues under compression

The aim of this study was to evaluate the elastic moduli of thyroid tissues under uniaxial compression and to establish the biomechanical fundamentals for accurate interpretation of thyroid elastograms. A total of 67 thyroid samples (24 samples of normal thyroid tissue, 2 samples of thyroid tissue with chronic thyroiditis, 12 samples of adenomatous goiter lesions and 7 samples of follicular adenoma, 19 samples of papillary adenocarcinoma (PAC) and 3 samples of follicular adenocarcinoma (FAC)) obtained from 36 patients who had received thyroid surgery were subjected to biomechanical testing within three hours after surgical resection at precompression strains of 5%, 10% and 20% and applied strains of 1%, 2%, 5% and 10% of sample height. As a result, the mean values of elastic moduli for benign thyroid lesions at all examined precompression levels were significantly higher than those for normal thyroid tissue measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, benign thyroid nodule samples were 1.7 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 2.4 times. Stiffness of PAC samples was significantly higher than those for normal thyroid tissue and benign thyroid tumors measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, PAC samples were 5.0 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 17.7 times. In contrast, samples of FAC were much softer than PAC (p<0.05) and were comparable in stiffness to normal thyroid tissues. The significant differences in the stiffness between normal thyroid tissue and thyroid tumors may provide useful information for accurate interpretation of thyroid elastograms.