Analysis of inconclusive fine-needle aspiration of thyroid follicular lesions

Role of multi-modality functional imaging in differentiation between benign and malignant thyroid 18F-fluorodeoxyglucose incidentaloma

PURPOSE

To evaluate the diagnostic performance of multi-modality functional imaging in differentiating malignant and benign thyroid ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) incidentaloma.

METHODS

This study included 87 patients with thyroid ¹⁸F-FDG incidentalomas detected by ¹⁸F-FDG- positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) and diagnosed at surgery or biopsy, who received ¹⁸F-FDG-PET/CT, diffusion-weighted MR imaging (DWI) and ultrasound elastography (USE). The metabolic tumor volume (MTV), total lesion glycolysis (TLG), apparent diffusion coefficient (ADC) values and ultrasound elasticity scores of thyroid ¹⁸F-FDG incidentalomas were measured and compared in benign and malignant thyroid incidentalomas. The differences of malignant and benign thyroid incidentalomas were tested by χ² test, Fisher's exact test, t test, or Mann-Whitney U test. The diagnostic performance was evaluated and optimal cut-off values were determined in distinguishing malignant from benign thyroid incidentalomas by receiver operating characteristic curve analysis.

RESULTS

MTV, TLG and USE scores of malignant thyroid incidentalomas were significantly higher than benign; but ADC value was significantly lower. We defined the functional imaging parameters TLG < 2.48, ADC > 1.80 × 10^-3mm²/s, and USE score of 1 as markers of benign thyroid incidentalomas and each scored -1 point; TLG ≥ 2.48, ADC ≤ 1.80 × 10^-3mm²/s, and USE score of 4 as markers of malignancy and each scored 1 point. Combined multi-functional imaging parameters achieved the highest performance (84.6% sensitivity and 97.1% specificity) for distinguish malignant from benign thyroid incidentaloma with AUC 0.957 (95% CI 0.917, 0.997).

CONCLUSIONS

Functional imaging might help to distinguishing malignant from benign thyroid ¹⁸F-FDG incidentalomas, and combined multi-functional imaging parameters could improve it.

Fine Needle Aspiration of Thyroid Nodules Using the Bethesda System for Reporting Thyroid Cytopathology: An Institutional Experience in a Rural Setting

Background. Fine needle aspiration (FNA) remains the first-line diagnostic in management of thyroid nodules and reduces unnecessary surgeries. However, it is still challenging since cytological results are not always straightforward. This study aimed to examine the results of thyroid FNA using the Bethesda system for reporting thyroid cytopathology (TBSRTC) to establish the level of accuracy of FNA procedures in a rural practice setting. Method. A retrospective chart review was conducted on existing thyroid FNA performed in a referral endocrine center between December 2011 and November 2015. Results. A total of 159 patients (18-88 years old) and 236 nodule aspirations were performed and submitted for evaluation. 79% were benign, 3% atypia/follicular lesion of unknown significance (AUS/FLUS), 5% follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), 4% suspicious for malignancy (one case was indeed an atypical parathyroid neoplasm by surgical pathology), 2% malignant, and 7% nondiagnostic. Two cases also had advanced molecular analysis on FNA specimens before thyroidectomy. Conclusion. The diagnostic yield of FNA cytology from our practice in a rural setting suggests that accuracy and specificity are comparable to results from larger centers.

Diagnostic value of diffusion-weighted MR imaging in thyroid disease: application in differentiating benign from malignant disease

Background

Fine needle aspiration biopsy is usually performed to evaluate thyroid lesions. The purpose of this study was to evaluate the usefulness of diffusion weighted imaging to differentiate malignancy of thyroid lesions.

Methods

The study was approved by ethics committee of Shanghai Changzheng Hospital.Forty-two patients, 10 men and 32 women (range: 20–72 years, mean age 42.4 years) with thyroid lesions were included in the study. Routine neck MR and diffusion-weighted MR imaging was performed using multiple b-values. ADC values were computed for the different b-values. Histological results of the thyroidectomy samples were obtained for all the patients. ADC values of benign and malignant thyroid lesions were compared with the pathology results. Logistic regression analysis was used to detect independent parameters for differentiating benign and malignancy of lesions.

Result

Based on the histology results there were 28 benign and 14 malignant cases. The difference of ADC value between benign and malignant thyroid lesions was significant for ADC values obtained using b-values of 0 and 300 s/mm² (p < 0.001). The ADC values were significantly higher in benign lesions (benign ADC: 2.37 ± 0.47 × 10-3 mm²/s vs. malignant: 1.49 ± 0.60 × 10-3 mm²/s). ADC values obtained with b-values of 0 and 300 mm²/s and max nodular diameter was regarded as the two most discriminative parameters for differentiating malignancy. Using the pathology results as a standard reference, area under ROC curve was found to be 0.876 for an ADC cutoff value of 2.17 × 10-3 mm²/s that corresponded to an acquisition with b-values of 0 and 300 mm²/s.

Conclusion

Diffusion-weighted MR imaging is a promising non-invasive method to differentiate malignancy in thyroid lesions.

Malignancy risk analysis in patients with inadequate fine needle aspiration cytology (FNAC) of the thyroid

BACKGROUND

Thyroid fine needle aspiration cytology (FNAC) is the standard diagnostic modality for thyroid nodules. However, it has limitations among which is the incidence of non-diagnostic results (Thy1). Management of cases with repeatedly non-diagnostic FNAC ranges from simple observation to surgical intervention. We aim to evaluate the incidence of malignancy in non-diagnostic FNAC, and the success rate of repeated FNAC. We also aim to evaluate risk factors for malignancy in patients with non-diagnostic FNAC.

MATERIALS AND METHODS

Retrospective analyses of consecutive cases with thyroid non diagnostic FNAC results were included.

RESULTS

Out of total 1657 thyroid FNAC done during the study period, there were 264 (15.9%) non-diagnostic FNAC on the first attempt. On repeating those, the rate of a non-diagnostic result on second FNAC was 61.8% and on third FNAC was 47.2%. The overall malignancy rate in Thy1 FNAC was 4.5% (42% papillary, 42% follicular and 8% anaplastic), and the yield of malignancy decreased considerably with successive non-diagnostic FNAC. Ultrasound guidance by an experienced head neck radiologist produced the lowest non-diagnostic rate (38%) on repetition compared to US guidance by a generalist radiologist (65%) and by non US guidance (90%).

CONCLUSIONS

There is a low risk of malignancy in patients with a non-diagnostic FNAC result, commensurate to the risk of any nodule. The yield of malignancy decreased considerably with successive non-diagnostic FNAC.

Prevalence of malignancy in thyroid nodules with an initial nondiagnostic result after ultrasound guided fine needle aspiration

The objective of this study was to determine the rate of malignancy in thyroid nodules with an initial nondiagnostic fine needle aspiration. From October 2001 to April 2007, biopsies were performed on 1344 thyroid nodules in our practice. Biopsies were performed on nodules using 25-27 gauge needles, ultrasound guidance and multiple passes using both suction and capillary action. We retrospectively reviewed the results of these biopsies as well as any further management of nodules that received nondiagnostic results (IRB HUM00006459). Following initial biopsy, 295/1344 (21.9%) of nodules received nondiagnostic pathologic results. Of this population, 39 nodules (13.1%) were lost to follow-up. Of the remaining 256 nodules that received a repeat FNA, surgical excision, or greater than 24 months of clinical and imaging follow-up, only five cancers were detected, representing only 2% of the population that received an initial nondiagnostic biopsy result. All of these cancers were papillary neoplasms. When rigorous, ultrasound-guided, fine needle aspiration of thyroid nodules is performed, a nondiagnostic histopathologic result should not be interpreted as suspicious for thyroid cancer. Given the low rate of malignancy in this population (2%), we suggest that clinical and imaging follow-up of these nodules, opposed to repeat sampling, is warranted.

Quality improvement by standardization of procurement and processing of thyroid fine-needle aspirates in the absence of on-site cytological evaluation

BACKGROUND

Thyroid nodules are relatively common and are routinely evaluated by fine-needle aspiration cytology, usually performed by clinicians. We noticed qualitative and/or quantitative variability in samples submitted to the cytopathology laboratory from clinicians, for example, the number of glass slides submitted (2-25) and air-dried smears versus alcohol-fixed slides, with variability in specimen adequacy and interpretability. The objective of this study was to standardize the preanalytic variables to determine if there is an improvement in the specimen quality.

METHODS

We standardized the method of collection (ultrasound-guided, 25-gauge needle, four passes) and preparation of samples (four total smears: two air-dried, two fixed, with liquid-based preparation and/or cell block) and personnel involved.

RESULTS

Standardization of thyroid nodule fine-needle aspiration and sample preparation by clinical staff resulted in an overall improvement in the quality of sample (odds ratio = 3.82, 95% confidence interval 2.02-7.24, p < 0.0001) with an increased proportion of satisfactory samples from 67% prestandardization to 89% poststandardization.

CONCLUSIONS

Standardization resulted in a significant improvement in specimen interpretability.

Fine-needle aspiration biopsy of benign thyroid nodules: an evidence-based review

BACKGROUND

Since the development of fine-needle aspiration biopsy (FNAB) techniques, preoperative diagnosis and subsequent strategies for patient treatment have changed and evolved greatly. This is true also for thyroid FNAB: the vast majority of thyroid nodules are benign, and hence do not necessarily require surgical treatment.

METHODS

A comprehensive Medline and Cochrane Library search was performed evaluating FNAB in the thyroid. In the last decade more than 400 articles on the subject have been published. Data in relation to the experience with FNAB at the Karolinska University Hospital since its introduction were also reviewed.

RESULTS

The development of FNAB since the 1960s at the Karolinska University Hospital is described. During the period 1992-1996 the accuracy of the clinical routine was evaluated by studying the outcomes of almost 4,000 FNAs of the thyroid. The results were good, with only a few false-negative and false-positive results, but the problem of differentiating follicular adenoma from follicular carcinoma remained a significant problem. The use of immunological analysis has greatly increased the possibility of obtaining valuable information on cellular characteristics.

CONCLUSION

A successful FNAB service rests on several factors, and the importance of clinical conferences between all specialists involved in the diagnosis and treatment of patients with thyroid disorders cannot be overemphasized. At the Karolinska University Hospital there are weekly conferences where patients are discussed both pre- and postoperatively. These conferences lead to optimal interaction between the different specialists and, most important, substantial improvement in the clinical management of patients with thyroid disorders.