Ultrasound-guided biopsy of the thyroid: A comparison of technique with respect to diagnostic accuracy

Molecular testing and thyroid nodule management in North America

The incidence of thyroid cancer is rising for a variety of reasons. At the same time, the nomenclature revision of non-invasive encapsulated follicular-variant PTC to noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP) has modified the incidence of thyroid cancer. Given that thyroid neoplasia is a molecular event, it is important for the thyroid physician to evaluate each patient systematically. Most thyroid cancers are sporadic; however, some are familial and may be associated with syndromes with genetic implications. Advances in radiologic imaging have made ultrasonography a near equivalent of gross examination. The American College of Radiology Thyroid Imaging, Reporting and Data System (ACR TI-RADS) classifies nodules from TR1 to TR5 and is valuable in determining which patients should be guided toward fine-needle aspiration (FNA) sampling. While FNA procedures and processing may be varied, the key elements are cytologic diagnosis and collection of samples for potential molecular testing. The Bethesda System for Reporting Thyroid Cytology (BSRTC) is commonly used and categorizes each FNA specimen into one of six diagnoses. The indeterminate diagnoses with risk of malignancy (ROM) ranging from 10-75% comprise approximately 30% of thyroid FNA cases and for these, molecular testing is beneficial. In North America, the two most common molecular platforms are Veracyte Afirma GSC and ThyroSeq v3. Both panels cover an extensive array of genomic alterations associated with thyroid neoplasia and a negative result from either test effectively refines the ROM of an Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) or Follicular Neoplasm/Suspicious for a Follicular Neoplasm (FN/SFN) diagnosis to 3-4%. Given that the refined ROMs are comparable to that of a Benign BSRTC diagnosis, these patients are recommended for observation of their nodules. However, differences exist in the implication of Afirma GSC-Suspicious and ThyroSeq v3-Positive molecular results with regard to the probability of cancer. For either test, the molecular test result should be integrated with other clinical parameters to determine if surgery is indicated and, if so, the extent of surgery.

Comparison of the collection approaches of 2 large thyroid fine-needle aspiration practices reveals differing advantages for cytology and molecular testing adequacy rates

INTRODUCTION

At our institution, almost all thyroid fine-needle aspiration (FNA) procedures are performed by either Endocrinology or Radiology personnel. In this study, we compared the cytology and molecular adequacy rates of these 2 thyroid FNA practices, which differ on several aspects of specimen procurement.

MATERIALS AND METHODS

All thyroid FNA specimens from Endocrinology and Radiology practices between September 2008 and December 2016 were included. Over this time frame, the molecular testing modality transitioned from polymerase chain reaction (PCR)-based (7-gene panel era) to next generation sequencing (NGS)-based (ThyroSeq era). In measuring cytology adequacy, the Bethesda System unsatisfactory rate was determined. Molecular adequacy was categorized as Optimal, Limited Thyroid Epithelial Cells, Limited Nucleic Acids, or Failed. These parameters were compared for the 2 practices.

RESULTS

The study cohorts comprised 5810 specimens from Endocrinology and 4597 from Radiology. More Endocrinology specimens were satisfactory for cytology diagnosis than those from Radiology (94.7% versus 90.0%, P < 0.001). For molecular adequacy, fewer Endocrinology specimens were optimal than specimens from Radiology for both the 7-gene panel era (76.2% versus 82.9%, P < 0.001) and the ThyroSeq era (88.1% versus 91.9%, P = 0.049).

CONCLUSIONS

The 2 thyroid FNA practices varied inversely in their adequacy rates for cytology and molecular testing. Had one practice been superior for both cytology and molecular adequacy, a recommendation for the method of choice would have been straightforward. However, our results show that optimization of FNA practice for the current practice of thyroid cytology requires further investigation due to the complex nature of specimen procurement.

Importance of FNA Technique for Decreasing Non-diagnostic Rates in Thyroid Nodules

To identify potential interventions that may lower the high non-diagnostic rates associated with ultrasound guided (US) fine needle aspiration (FNA) biopsy of the thyroid nodule. A case series of 164 thyroid nodule US-guided FNA was identified retrospectively. The following variables were analyzed in regards to diagnostic and non-diagnostic sampling: patient age, gender, size of nodule, biopsy technique (capillary vs. aspiration), needle gauge (23 vs. 25), and physician experience. The FNA diagnosis, and final pathology, when applicable, was recorded for each sample using the Bethesda criteria. Data was analyzed using the Fisher's exact test or the chi square test. After multivariate logistic regression, capillary action was independently associated with lower non-diagnostic rates (p = 0.01), while increasing patient age was associated with higher non-diagnostic rates (p = 0.018). Physician experience (p = 0.014) was not independently associated with lower non-diagnostic rates. Nodules that were "cystic >50%" were significantly more likely to yield a non-diagnostic result (p < 0.0001). After taking into account confounding variables, including physician experience, our data reveals a statistically significant decrease in non-diagnostic rates with the use of capillary action vs. aspiration technique in US-guided FNA. A major focus in healthcare today is providing cost-effective and minimally invasive care to the patient. In the setting of a rising incidence of thyroid disease, we believe our study demonstrates the need for a prospective analysis of the relationship between technique and non-diagnostic rates.

Diagnostic accuracy of ultrasound-guided fine needle aspiration biopsy for thyroid malignancy: systematic review and meta-analysis

PURPOSE

To systematically appraise and summarize the available evidence about the diagnostic accuracy of ultrasound-guided fine needle aspiration biopsy (USFNA) for thyroid malignancy, and to explore the integration of these estimates with the probability of thyroid malignancy before USFNA.

METHODS

A comprehensive search of multiple databases from each database's inception to August 2014 was performed. Eligible studies included those that evaluated patients with thyroid nodules who underwent USFNA and subsequent evaluation by histopathology or long-term follow-up.

RESULTS

We identified 32 studies at moderate risk of bias evaluating the USFNA diagnostic characteristics for the diagnosis of thyroid malignancy. Results were imprecise and inconsistent across trials. The pooled likelihood ratio (LR) of thyroid malignancy for a benign USFNA result was 0.09 (95 % CI 0.06, 0.14; I (2) = 33 %), whereas the pooled LR for a malignant result was 197 (95 % CI, 68, 569; I (2) = 77 %). In the case of a suspicious for follicular neoplasm result, the pooled LR for malignancy was 0.6 (95 % CI, 0.4, 1.0; I (2) = 84 %) and 8.3 (95 % CI, 3.6, 19.2; I (2) = 89) for a result of suspicious for malignancy.

CONCLUSION

The available evidence regarding the diagnostic accuracy of USFNA warrants only limited confidence due to risk of bias, imprecision, and inconsistency. However, some USFNA results (benign, malignant) are likely very helpful, by significantly changing the pre-test probability of thyroid cancer.

Comparison of Fine Needle Aspiration and Fine Needle Nonaspiration Cytology of Thyroid Nodules: A Meta-Analysis

Background. Fine needle aspiration cytology (FNAC) and fine needle nonaspiration cytology (FNNAC) are useful cost-effective techniques for preoperatively assessing thyroid lesions. Both techniques have advantages and disadvantages, and there is controversy over which method is superior. This meta-analysis was performed to evaluate the differences between FNAC and FNNAC for diagnosis of thyroid nodules. Methods. Primary publications were independently collected by two reviewers from PubMed, Web of Science, Google Scholar, EBSCO, OALib, and the Cochrane Library databases. The following search terms were used: fine needle, aspiration, capillary, nonaspiration, sampling without aspiration, thyroid, and cytology. The last search was performed on February 1, 2015. Results. Sixteen studies comprising 1,842 patients and 2,221 samples were included in this study. No statistically significant difference was observed between FNAC and FNNAC groups with respect to diagnostically inadequate smears, diagnostically superior smears, diagnostic performance (accuracy, sensitivity, specificity, negative predictive value, and positive predictive value), area under the summary receiver operating characteristic curve, average score of each parameter (background blood or clot, amount of cellular material, degree of cellular degeneration, degree of cellular trauma, and retention of appropriate architecture), and total score of five parameters. Conclusion. FNAC and FNNAC are equally useful in assessing thyroid nodules.

A systematic review of ultrasound-guided FNA of lesions in the head and neck--focusing on operator, sample inadequacy and presence of on-spot cytology service

The objective of this review is to perform a systematic review of ultrasound-guided fine-needle aspiration (FNA) services for head and neck lesions with assessment of inadequacy rates and related variables such as the presence of immediate cytological assessment. A computer-based systematic search of articles in English language was performed using MEDLINE (1950 to date) from National Health Service evidence healthcare database and PubMed. Full texts of all relevant articles were obtained and scrutinized independently by two authors according to the stated inclusion and exclusion criteria. The primary search identified 932 articles, but only 78 met all the study criteria. The overall inadequacy rate was 9.3%, 16 studies had on-site evaluation by a cytopathologist/specialist clinician with a rate of 6.0%. In seven studies, a cytotechnician was available to either assess the sample or prepare the slides with an average inadequacy rate of 11.4%. In 1 study, the assessment was unclear, but the inadequacy rate for the remaining 54 studies, without immediate assessment, was 10.3%. The rate for the cytopathologist/specialist clinicians was significantly different to no on-site assessment but this was not found for assessment by cytotechnicians. The review suggests that the best results are obtained with a cytopathologist-led FNA service, where the pathologist reviews the specimen immediately, in relation to the clinical context, thereby deciding on adequacy and need for further biopsies. A systematic review looking at ultrasound-guided FNA of head and neck lesions has not been published previously.

Ultrasound-guided fine-needle aspiration biopsy of the thyroid: methods to decrease the rate of unsatisfactory biopsies in the absence of an on-site pathologist

PURPOSE

The rate of unsatisfactory samples from ultrasound-guided fine-needle aspirations of thyroid nodules varies widely in the literature. We aimed to evaluate our thyroid ultrasound-guided fine-needle aspiration biopsy technique in the absence of on-site microscopic examination by a pathologist; determine factors that affect the adequacy rate, such as the number of needle passes and needle size; compare our results with the literature; and establish an optimal technique.

MATERIALS AND METHODS

We performed a retrospective review of cytopathology reports from 252 consecutive thyroid ultrasound-guided fine-needle aspiration biopsies performed by a radiologist between 2005 and 2010 in our hospital's radiology department. Sample adequacy, the number of needle passes, and needle size were determined. There was an on-site cytologist who prepared slides immediately after fine-needle aspiration but no on-site microscopic assessment of sample adequacy to guide the number of needle passes that should be performed. Cytopathology biopsy reports were classified as either unsatisfactory or satisfactory samples for diagnosis; the latter consisted of benign, malignant, and undetermined diagnoses.

RESULTS

Seventy-seven biopsies were performed with 1 needle pass, 124 with 2 needle passes, and 51 with 3 needle passes. The rates of unsatisfactory biopsies were 33.8%, 23.4% (odds ratio [OR] 0.599 [95% confidence interval {CI}, 0.319-1.123]; P = .110), and 13.7% (OR 0.312 [95% CI, 0.124-0.788]; P = .014), respectively.

CONCLUSION

In a hospital in which there is no on-site pathologist, a 3-pass method increases the specimen satisfactory rate by 20% compared with 1 pass, achieves similar rates to the literature, and provides a basis for further improvement of our practice.

Role of ultrasonography in thyroid disease

Ultrasonography (US) is the single-most valuable imaging modality in the evaluation of the thyroid gland. This review discusses the US appearances of thyroid nodules, emphasizing sonographic features associated with potentially malignant or, at the other end of the spectrum, likely benign nodules. Diffuse thyroid abnormalities have also been reviewed. The technique of ultrasound-guided fine-needle aspiration biopsy and the emerging role of elastography in characterizing thyroid nodules have also been addressed.

Adequacy and diagnostic accuracy of aspiration vs. capillary fine needle thyroid biopsies

Thyroid nodules can be biopsied by fine needle aspiration (FNA) or fine needle capillary (FNC) biopsies. However, there is controversy on whether one technique is superior to another. In a randomized cytopathologist-blinded cross-sectional study, 260 patients (238 females, age 43.2 +/- 12.6) with nodular (82.7%) and diffuse goiter (17.3%) underwent 520 FNAs and 520 FNCs (not guided by ultrasound). Smears were scored for sample adequacy, and diagnosed as malignant, benign, suspicious, or nondiagnostic. Diagnostic accuracy was calculated based on the histological findings of 58 patients submitted to surgery. Intra-technique diagnostic accuracy and sample adequacy was seen in all samples. FNA and FNC provided similar cytological diagnosis, respectively (benign: 75.8% vs. 74.2%, p = 0.600; malignant: 3.8% vs. 3.8%, p = 0.871; suspicious: 10.4% vs. 10.8%, p = 0.913; and nondiagnostic: 10.0% vs. 11.2%, p = 0.598). Adequacy scores were similar by FNA (7.94 +/- 2.84) and FNC (7.96 +/- 2.81, p = 0.909). The same proportion of adequate or superior samples was seen in both techniques (91.6%). Sensitivity was equal to 85.7% for FNA and 100% for FNC. Similarly, specificity was 100% for both techniques. FNA and FNC provide the similar sample adequacy and diagnostic accuracy. The choice of technique should be based on the operator's personal preferences and experience.