Exploring Radiofrequency Ablation for T1 Papillary Thyroid Cancer in the United States: Mayo Clinic Experience.

OBJECTIVE: To report the efficacy, safety, and feasibility of radiofrequency ablation (RFA) for T1 papillary thyroid carcinoma (PTC) in a large referral center in the United States. PATIENTS AND METHODS: We conducted a retrospective study of 8 patients who underwent RFA for T1 PTC at Mayo Clinic in Rochester Minnesota, between July 1, 2020, and February 28, 2023. The RFA technique and the type of anesthesia are described. Thyroid function, changes in ablated zone, and adverse events were analyzed for up to 24 months after the procedure. RESULTS: Of the 8 patients included in the study, 7 were female and 1 was male with a mean ± SD age of 53±16.4 years. Thyroid status was unaffected in 7 of the 8 patients. The median duration of RFA was 6 minutes (range, 2 to 14.5 minutes) with energy delivered at between 25 and 45 W. The mean ± SD volume of small PTCs was 0.3±0.2 mL, and the mean largest diameter was 9.5±3.3 mm (range, 6 to 15 mm). The mean ± SD ablated volume at 3 to 6 months was larger than the target lesion (0.8±0.7 mL), with a reduction in mean ± SD ablated volume of 0.4±0.4 mL at 7 to 12 months and 0.1±0.06 mL at 13 to 18 months. The ablated zone almost disappeared at 19 to 24 months (0.04±0.04 mL). There were no major adverse events during or after the RFA procedure. CONCLUSION: This is the first reported series of T1 PTC treated with RFA in the United States. Early postablation imaging revealed that the ablated region was larger than the target lesions, followed by a serial decrease in size. Therefore, RFA at centers with such expertise appears to be a safe and effective treatment for small PTCs. Further studies are needed to evaluate its long-term efficacy and the risk of recurrence.

Ethanol ablation of papillary thyroid carcinoma nodal metastases: Long-term outcomes.

BACKGROUND: Percutaneous ethanol ablation has emerged as a treatment for recurrent papillary thyroid carcinoma in the lateral neck after compartment-oriented therapeutic lymphadenectomy. However, the safety and utility of percutaneous ethanol ablation as a primary treatment modality for lateral neck metastases remains undefined. We aimed to investigate long-term outcomes of percutaneous ethanol ablation of lateral neck papillary thyroid carcinoma recurrence both with and without prior lymphadenectomy. METHODS: We conducted a retrospective study of patients with lateral neck papillary thyroid carcinoma treated with percutaneous ethanol ablation from 2013 to 2018. Patient characteristics, disease volume, morbidity, and recurrence (development of new lymphadenopathy within a percutaneous ethanol ablation-treated nodal compartment) were assessed. RESULTS: We identified 117 patients who underwent percutaneous ethanol ablation for papillary thyroid carcinoma lateral neck metastases-67 (57%) had a prior lateral neck dissection. Median follow-up after percutaneous ethanol ablation was 5.5 years (interquartile range 3.1-7.5). On average, 1.4 lymph nodes (range: 1-6) were treated. Three patients (3%) developed transient nerve-related complications after percutaneous ethanol ablation. Of 15 patients who underwent lateral neck dissection after percutaneous ethanol ablation (including patients undergoing repeat lateral neck dissection), dissection was "difficult" in 8 (53%) (7 of whom had previously undergone lateral neck dissection), and 4 (27%) developed complications (transient nerve dysfunction = 3, lymphatic leak = 1). Thirty-three patients (28%) developed recurrent papillary thyroid carcinoma. No difference in recurrence was seen between patients who did or did not undergo pre-percutaneous ethanol ablation lateral neck dissection (no pre-percutaneous ethanol ablation lateral neck dissection: 24%, pre-percutaneous ethanol ablation lateral neck dissection, 31%; hazard ratio = 1.27, 95% confidence interval 0.62-2.58; P = .514). CONCLUSION: Percutaneous ethanol ablation may be a safe primary treatment modality for papillary thyroid carcinoma lateral neck nodal recurrence in selected patients with low-volume nodal disease.

Clinician feedback using a shared decision-making tool for the evaluation of patients with thyroid nodules-an observational study.

BACKGROUND: We pilot-tested an encounter conversation aid to support shared decision making (SDM) between patients with thyroid nodules and their clinicians. OBJECTIVE: Characterize the clinician feedback after providing care to patients with thyroid nodules using a tool to promote SDM conversations during the clinical encounter, and evaluate how clinicians used the tool during the visit. METHODS: Mixed method study in two academic centers in the U.S., including adult patients presenting for evaluation of thyroid nodules and their clinicians. We thematically analyzed interviews with clinicians after they used the SDM tool in at least three visits to characterize their feedback. Additionally, investigators evaluated visits recordings to determine the extent to which clinicians engaged patients in the decision-making process (OPTION score, scale 0 to 100, higher levels indicating higher involvement), the tool's components used (fidelity), and encounter duration. Using a post-visit survey, we evaluated the extent to which clinicians felt the tool was easy to use, helpful, and supportive of the patient-clinician collaboration. RESULTS: Thirteen clinicians participated in the study and used the SDM tool in the care of 53 patients. Clinicians thought the tool was well-organized and beneficial to patients and clinicians. Clinicians noticed a change in their routine with the use of the conversation aid and suggested it needed to be more flexible to better support varying conversations. The median OPTION score was 34, the fidelity of use 75%, and the median visit duration 17 min. In most encounters, clinicians agreed or strongly agreed the tool was easy to use (86%), helpful (65%), and supported collaboration (62%). CONCLUSION: Clinicians were able to use a SDM tool in the care of patients with thyroid nodules. Although they wished it were more flexible, they found on the whole that its use in the clinical encounter was beneficial to patients and clinicians.

Patient feedback receiving care using a shared decision making tool for thyroid nodule evaluation-an observational study.

PURPOSE: To characterize the feedback of patients with thyroid nodules receiving care using a shared decision making (SDM) tool designed to improve conversations with their clinicians related to diagnostic options (e.g. thyroid biopsy, ultrasound surveillance). METHODS: Investigators qualitatively analyzed post-encounter interviews with patients to characterize their feedback of a SDM tool used during their clinical visits. Additionally, investigators counted instances of diagnostic choice awareness and of patients' expression of a diagnostic management preference in recordings of clinical encounters of adult patients presenting for evaluation of thyroid nodules in which the SDM tool was used. RESULTS: In total, 53 patients (42 (79%) women); median age 62 years were enrolled and had consultations supported by the SDM tool. Patients were favorable about the design of the SDM tool and its ability to convey information about options and support patient-clinician interactions. Patients identified opportunities to improve the tool through adding more content and improve its use in practice through training of clinicians in its use. There was evidence of diagnostic choice awareness in 52 (98%) of these visits and patients expressed a diagnostic management preference in 40 (76%). CONCLUSION: User centered design including feedback from patients and real life observation supports the use of the SDM tool to facilitate collaboration between patients and clinicians.

Radiofrequency Ablation of Benign and Malignant Thyroid Nodules.

Thyroid nodule treatment has significantly evolved over recent years with attempts to individualize treatment on the basis of the cause of the nodule and patient performance status. The risks and complications associated with surgery and radioactive iodine have promoted interest in additional therapies such as radiofrequency ablation (RFA). RFA creates an electrical current through a target tissue (thyroid nodule) with resultant tissue heating causing coagulative necrosis. National and international groups are beginning to recognize the role of RFA as a viable therapeutic option in the treatment of thyroid nodules. Based on numerous guidelines, RFA is indicated in the treatment of symptomatic benign nodules and autonomously functioning nodules when surgery is refused or when the patient would not tolerate surgery. The treatment of thyroid malignancy with RFA is controversial, with some groups advocating for its use in the treatment of small papillary thyroid cancers in specific scenarios. The most important aspect of RFA is the preprocedural workup and adequate patient selection. Procedural technique varies among centers. However, RFA is typically performed as a single-day-admission outpatient procedure. Methods such as hydrodissection and a moving shot technique are employed to ensure adequate coverage of the nodule without overtreating the peripheries and damaging sensitive structures. As a result, the procedure is well tolerated, and major complications such as recurrent laryngeal nerve injury and nodule rupture are very rare. In the proper patient cohort, thyroid RFA offers an efficacious and safe option in the management of thyroid nodules. An invited commentary by Filippiadis and Vrachliotis is available online. ©RSNA, 2022.

Clinician Agreement on the Classification of Thyroid Nodules Ultrasound Features: A Survey of 2 Endocrine Societies.

CONTEXT: Thyroid nodule risk stratification allows clinicians to standardize the evaluation of thyroid cancer risk according to ultrasound features. OBJECTIVE: To evaluate interrater agreement among clinicians assessing thyroid nodules ultrasound features and thyroid cancer risk categories. DESIGN, SETTING, AND PARTICIPANTS: We surveyed Endocrine Society and Latin American Thyroid Society members to assess their interpretation of composition, echogenicity, shape, margins, and presence of echogenic foci of 10 thyroid nodule cases. The risk category for thyroid cancer was calculated following the American College of Radiology-Thyroid Imaging Reporting & Data System (ACR-TIRADS) framework from individual responses. MAIN OUTCOMES AND MEASURES: We used descriptive statistics and Gwet's agreement coefficient (AC1) to assess the primary outcome of interrater agreement for ACR-TIRADS risk category. As secondary outcomes, the interrater agreement for individual features and a subgroup analysis of interrater agreement for the ACR-TIRADS category were performed (ultrasound reporting system, type of practice, and number of monthly appraisals). RESULTS: A total of 144 participants were included, mostly endocrinologists. There was moderate level of agreement for the absence of echogenic foci (AC1 0.53, 95% CI 0.24-0.81) and composition (AC1 0.54, 95% CI 0.36-0.71). The agreement for margins (AC1 0.24, 95% CI 0.15-0.33), echogenicity (AC1 0.34, 95% CI 0.22-0.46), and shape assessment (AC1 0.42, 95% CI 0.13-0.70) was lower. The overall agreement for ACR-TIRADS assessment was AC1 0.29, (95% CI 0.13-0.45). The AC1 of ACR-TIRADS among subgroups was similar. CONCLUSIONS: This study found high variation of judgments about ACR-TIRADS risk category and individual features, which poses a potential challenge for the widescale implementation of thyroid nodule risk stratification.

Nonsurgical Management of Thyroid Nodules: The Role of Ablative Therapies.

CONTEXT: After a thorough evaluation most thyroid nodules are deemed of no clinical consequence and can be observed. However, when they are compressive, toxic, or involved by papillary thyroid carcinoma surgery or radioactive iodine (RAI) (if toxic) are the treatments of choice. Both interventions can lead to hypothyroidism and other adverse outcomes (eg, scar, dysphonia, logistical limitation with RAI). Active surveillance might be used for papillary thyroid microcarcinoma (PTMC) initially, but anxiety leads many cases to surgery later. Several ablative therapies have thus evolved over the last few years aimed at treating these nodules while avoiding described risks. CASES: We present 4 cases of thyroid lesions causing concern (compressive symptoms, thyrotoxicosis, anxiety with active surveillance of PTMC). The common denominator is patients' attempt to preserve thyroid function, bringing into focus percutaneous ethanol injection (PEI) and thermal ablation techniques (radiofrequency ablation [RFA] being the most common). We discuss the evidence supporting these approaches and compare them with standard therapy, where evidence exists. We discuss additional considerations for the utilization of these therapies, their side-effects, and conclude with a simplified description of how these procedures are performed. CONCLUSION: Thermal ablation, particularly RFA, is becoming an attractive option for managing a subgroup of solid thyroid nodules, while PEI has a role in managing thyroid cysts and a select group of PTMC. Their role in the algorithm of thyroid nodule management is still being refined and technical expertise will be essential to reproduce the reported results into everyday practice.

Thyroid Nodule Size as a Predictor of Malignancy in Follicular and Hurthle Neoplasms.

INTRODUCTION: The management of follicular (FN) and Hurthle cell neoplasms (HCN) is often difficult because of the uncertainty of malignancy risk. We aimed to assess characteristics of benign and malignant follicular and Hurthle neoplasms based on their shape and size. MATERIALS AND METHODS: Patients with Follicular adenoma (FA) or carcinoma (FC) and Hurthle Cell adenoma (HCA) or carcinoma (HCC) who had preoperative ultrasonography were included. Demographic data were retrieved. Size and shape of the nodules were measured. Logistic regression analyses and odds ratios were performed. RESULTS: A total of 115 nodules with 57 carcinomas and 58 adenomas were included. Logistic regression analysis shows that the nodule height and the patient age are predictors of malignancy (p-values = 0.001 and 0.042). A cutoff value of nodule height ≥ 4 cm. produces an odds ratio of 4.5 (p-value = 0.006). An age ≥ 55 year-old demonstrates an odds ratio of 2.4-3.6 (p-value = 0.03). Taller-than-wide shape was not statistically significant (p-value = 0.613). CONCLUSION: FC and HCC are larger than FA and HCA in size, with a cutoff at 4 cm. Increasing age increases the odds of malignancy with a cutoff at 55 year-old. Taller-than-wide shape is not a predictor of malignancy.

Radiologic and clinicopathologic characteristics of thyroid nodules with focal 68Ga-DOTATATE PET activity.

OBJECTIVE: Our aim was to determine the radiologic and clinicopathologic characteristics of thyroid nodules with focal 68Ga-DOTATATE activity. METHODS: In this retrospective study of 1927 consecutive 68Ga-DOTATATE PET scans, 85 patients with incidental and nonincidental focal 68Ga-DOTATATE avid thyroid nodules were identified, of which 31 patients with 33 thyroid nodules underwent fine-needle aspiration (FNA) or surgery. These 33 nodules were reviewed for Krenning score and SUVmax of the thyroid nodule, contralateral thyroid lobe and left atrium. RESULTS: Cytology/histopathology included 58% (19/33) with benign findings, 18% (6/33) medullary thyroid carcinoma (MTC), 9% (3/33) atypia or follicular lesion of undetermined significance (AUS/FLUS), 9% (3/33) suspicious for follicular neoplasm and Hurthle cell adenoma (SFN/HCA) and 6% (2/33) nondiagnostic cytology. Median serum calcitonin was 1156 pg/mL (range, 460-1828) in MTC and was <5.0 pg/mL (<5.0-12.5) in patients with benign nodules. Nodules had Krenning score of 1, 2 and 3 in 46% (15/33), 27% (9/33) and 27% (9/33). The majority of MTC and AUS/FLUS nodules had a Krenning score of 3, and there was substantial intragroup variation in Krenning score among the benign nodules. The mean SUVmax for the entire cohort was 5.5 ± 2.9 (mean ± SD), and the range was 2.0-13.0. There was overlap in the nodule/contralateral thyroid SUVmax ratios between groups. The MTC and AUS/FLUS nodules tended to have a higher nodule/blood pool SUVmax ratio than the other pathologic groups. CONCLUSION: There was considerable variation in radiologic characteristics among benign thyroid nodules. The ratio of thyroid nodule SUVmax/blood pool SUVmax may be useful to differentiate pathologic groups, but larger studies are needed to investigate this further. Given the potential for malignancy in thyroid nodules with focal 68Ga-DOTATATE activity, further evaluation with serum calcitonin and FNA may be considered.Video Abstract: http://links.lww.com/NMC/A186.

Predicting Outcomes in Sporadic and Hereditary Medullary Thyroid Carcinoma over Two Decades.

Background: Medullary thyroid cancer (MTC) can be associated with significant morbidity and mortality in advanced cases. Hence, we aimed to identify factors at the time of MTC surgery that predict overall survival (OS), disease-specific survival (DSS), locoregional recurrence/persistence (LR), and distant metastases (DM). Methods: We performed a retrospective study of clinicopathologic, radiological, and laboratory data in MTC patients who underwent thyroidectomy at Mayo Clinic from January 1995 to December 2015. Results: We identified 163 patients (mean age 48.4 years, 48% males), 102 with sporadic MTC and 61 with hereditary disease (n = 46 multiple endocrine neoplasia [MEN] 2A, n = 3 MEN 2B, n = 12 familial MTC) with a median follow-up time of 5.5 years. On univariate analysis, age >55 years, male sex, DM at the time of surgery (M1), lateral neck lymph node (LN) involvement (N1b), gross extrathyroidal extension (ETE), American Joint Committee on Cancer (AJCC) stage 3/4, tumor size (T) 3/4, tumor size, and postoperative calcitonin (Ctn) and carcinoembryonic antigen (CEA) were significant predictors of worse OS and DSS. On multivariable analysis, both gross ETE (hazard ratio [HR] 4.62, 6.58) and M1 (HR 5.11, 10.45) remained significant predictors of worse OS as well as DSS, while age >55 years (HR 3.21), male sex (HR 2.42), and postoperative Ctn (HR 1.002 for every 100 pg/mL increase) were significant only for worse OS. On univariate analysis, male sex, M1, N1b, gross ETE, stage 3/4, T 3/4, tumor size, number of LNs involved, and postoperative Ctn were significant predictors of LR and DM; age >55 years was additionally significant for DM. On multivariable analysis, gross ETE (HR 3.16, 5.93) and N1b (HR 4.31, 4.64) remained significant predictors of LR and DM; ratio of resected/involved LN (HR 10.91) was additionally predictive for LR and postoperative Ctn (HR 1.003 for every 100 pg/mL increase) for DM. Conclusions: Disease burden at initial surgery, especially gross ETE, lateral neck LN involvement, and DM, as well as the biochemical response to surgery appear to be more important than demographic factors in terms of MTC prognosis. These findings highlight the importance of rigorous perioperative assessment to better predict MTC outcomes.

PANCYTOPENIA SECONDARY TO AUTOIMMUNE VITAMIN B12 DEFICIENCY IN GRAVES DISEASE.

OBJECTIVE: To describe a case of Graves disease (GD) and coexistent pancytopenia associated with autoimmune vitamin B12 deficiency. While thyrotoxicosis and antithyroid drugs can cause pancytopenia, other autoimmune conditions such as vitamin B12 deficiency can occur, leading to severe anemia and pancytopenia. METHODS: A 19-year-old female with GD treated with methimazole presented with thyrotoxicosis and evidence of pancytopenia. Diagnostic studies included a complete blood cell count, peripheral blood smears, thyroid function tests, and a bone marrow biopsy. RESULTS: White blood cells were 2.4 × 109 cells/L (reference range [RR] is 3.4 to 9.6 × 109 cells/L), hemoglobin was 7.9 g/dL (RR is 11.6 to 15.0 g/dL), neutrophil count was 1.2 × 109 cells/L, and platelets were 84 × 109 cells/L (RR is 157 to 371 × 109 cells/L). Thyroid-stimulating hormone was <0.01 mIU/L (RR is 0.50 to 4.30 mIU/L), free thyroxine was 3.7 ng/dL (RR is 1.0 to 1.6 ng/dL), and total triiodothyronine was 221 ng/dL (RR is 91 to 218 ng/dL). Due to suspicion for drug-induced pancytopenia, methimazole was discontinued. Three days later, she was hospitalized for a syncopal episode with a further decline in hemoglobin to 6.7 g/dL, neutrophils to 0.68 × 109 cells/L, and platelets to 69 × 109 cells/L. Bone marrow biopsy findings showing marrow hypercellularity and hypersegmented neutrophils suggested vitamin B12 deficiency. Vitamin B12 was <70 ng/L (RR is 180 to 914 ng/L). Intramuscular vitamin B12 injections were initiated, and pancytopenia resolved within 1 month. CONCLUSION: Although rarely described in the literature, autoimmune vitamin B12 deficiency can be missed as an underlying etiology for pancytopenia in patients with GD. The clinical picture can be further confounded when these patients are treated with antithyroid drugs known to cause bone marrow suppression.

Long-Term Results of Treating With Ethanol Ablation 15 Adult Patients With cT1aN0 Papillary Thyroid Microcarcinoma.

BACKGROUND: Currently acceptable management options for patients with adult papillary thyroid microcarcinoma (APTM) range from immediate surgery, either unilateral lobectomy or bilateral lobar resection, to active surveillance (AS). An alternative minimally invasive approach, originally employed for eliminating neck nodal metastases, may be ultrasound-guided percutaneous ethanol ablation (EA). Here we present our experience of definitively treating with EA 15 patients with APTM. PATIENTS AND METHODS: During 2010 through 2017, the 15 cT1aN0M0 patients selected for EA were aged 36 to 86 years (median, 45 years). Tumor volumes (n = 17), assessed by sonography, ranged from 25 to 375 mm3 (median, 109 mm3). Fourteen of 15 patients had 2 ethanol injections on successive days; total volume injected ranged from 0.45 to 1.80 cc (median, 1.1 cc). All ablated patients were followed with sonography and underwent recalculation of tumor volume and reassessment of tumor perfusion at each follow-up visit. RESULTS: The ablated patients have now been followed for 10 to 100 months (median, 64 months). There were no complications and no ablated patient developed postprocedure recurrent laryngeal nerve dysfunction. All 17 ablated tumors shrank (median 93%) and Doppler flow eliminated. Median tumor volume reduction in 9 identifiable avascular foci was 82% (range, 26%-93%). After EA, 8 tumors (47%) disappeared on sonography after a median of 10 months. During follow-up no new PTM foci and no nodal metastases have been identified. CONCLUSIONS: Definitive treatment of APTM by EA is effective, safe, and inexpensive. Our results suggest that, for APTM patients who do not wish neck surgery and are uncomfortable with AS, EA represents a well-tolerated and minimally invasive outpatient management option.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment.

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

Ethanol Ablation for the Treatment of Cystic and Predominantly Cystic Thyroid Nodules.

OBJECTIVE: To determine the efficacy and safety of percutaneous ethanol injection (PEI) for the treatment of symptomatic cystic thyroid nodules. PATIENTS AND METHODS: Retrospective analysis of patients with benign cystic thyroid nodules treated with PEI from February 1, 2000, through October 31, 2016. The main outcomes were efficacy, defined as symptom relief or reduction in nodule volume of 50% or more, and safety, defined as no or minor adverse events. RESULTS: Twenty patients had PEI. Mean age at the time of PEI was 50 years, and 13 (65%) were women; all patients were euthyroid. Twelve patients (60%) had complex cystic thyroid nodules (>50% cystic component), with the rest being purely cystic. The median largest diameter of the thyroid cyst was 4.5 cm (interquartile range [IQR], 3.2-5.3 cm; range, 2.3-8.0 cm); the median volume pre-PEI was 19.6 mL (IQR, 10.4-48.5 mL; range, 2.8-118.1 mL). The median amount of cystic fluid drained before PEI was 13.5 mL (IQR, 6.8-32.3 mL), and the median amount of ethanol administered was 3 mL (IQR, 2-5 mL; range, 0.5-20 mL). After median follow-up of 2 years, 17 of 19 patients (89%) were asymptomatic. Of 10 patients with available imaging on follow-up, 7 (70%) had a 50% or greater reduction in nodule volume (median volume decrease, 75.64% [IQR, 41.40%-91.99%]). Adverse effects occurred in 4 patients (20%) and were mild and temporary (slight pain, vagal reaction, and bleeding into the cyst). CONCLUSION: Percutaneous ethanol injection seems to be a safe and effective alternative to surgical resection for patients with purely or predominantly cystic thyroid nodules and compressive symptoms who decline surgery or are not good surgical candidates.

Outcomes of Radiofrequency Ablation Therapy for Large Benign Thyroid Nodules: A Mayo Clinic Case Series.

OBJECTIVE: To assess the effectiveness, tolerability, and complications of radiofrequency ablation (RFA) in patients with benign large thyroid nodules (TNs). PATIENTS AND METHODS: This is a retrospective review of 14 patients with predominantly solid TNs treated with RFA at Mayo Clinic in Rochester, Minnesota, from December 1, 2013, through October 30, 2016. All the patients declined surgery or were poor surgical candidates. The TNs were benign on fine-needle aspiration, enlarging or causing compressive symptoms, and 3 cm or larger in largest diameter. We evaluated TN volume, compressive symptoms, cosmetic concerns, and thyroid function. RESULTS: Median TN volume reduction induced by RFA was 44.6% (interquartile range [IQR], 42.1%-59.3%), from 24.2 mL (IQR, 17.7-42.5 mL) to 14.4 mL (IQR, 7.1-19.2 mL) (P<.001). Median follow-up was 8.6 months (IQR, 3.9-13.9 months). Maximum results were achieved by 6 months. Radiofrequency ablation did not affect thyroid function. In 1 patient with subclinical hyperthyroidism due to toxic adenoma, thyroid function normalized 4 months after ablation of the toxic nodule. Compressive symptoms resolved in 8 of 12 patients (67%) and improved in the other 4 (33%). Cosmetic concerns improved in all 8 patients. The procedure had no sustained complications. CONCLUSION: In this population, RFA of benign large TNs performed similarly to the reports from Europe and Asia. It induces a substantial volume reduction of predominantly solid TNs, improves compressive symptoms and cosmetic concerns, and does not affect normal thyroid function. Radiofrequency ablation has an acceptable safety profile and should be considered as a low-risk alternative to conventional treatment of symptomatic benign TNs.

Examining the Role of Preoperative Positron Emission Tomography/Computerized Tomography in Combination with Ultrasonography in Discriminating Benign from Malignant Cytologically Indeterminate Thyroid Nodules.

BACKGROUND: Cytologically defined indeterminate thyroid nodules are a diagnostic challenge. Surgical lobectomy remains the gold standard for definitive diagnosis. However, 70-85% of nodules are ultimately benign. The primary objective of this study was to evaluate the negative predictive value (NPV) of F18-fluorodeoxyglucose (FDG) positron emission computed tomography (PET/CT) in excluding cancer among cytologically indeterminate thyroid nodules within the authors' institution using surgical pathology as the gold-standard reference. In addition, a systematic review was performed of published prospective studies on the NPV of PET/CT in evaluating indeterminate thyroid nodules. METHODS: A retrospective review was performed of all patients aged ≥18 years seen at the Mayo Clinic between January 1, 2000, and December 31, 2014, with cytologically defined indeterminate thyroid nodules (suspicious for Hürthle cell neoplasm or follicular neoplasm; N = 858), who had a PET/CT within one year of fine-needle aspiration (n = 80) and underwent definitive diagnostic lobectomy (n = 51). Nodules were considered PET negative if they had a standardized uptake value (SUV) <5. Additionally, a systematic review was performed of published prospective studies on the NPV of PET/CT across multiple sites. RESULTS: Fifty-one patients met the eligibility criteria. The retrospective review combined with a systematic review of eight prospective studies suggests that indeterminate nodules with a negative PET (SUV <5) have a low risk of malignancy (NPV 94%). The cancer prevalence in the institution is 14% and 27% in the combined prospective studies. CONCLUSIONS: PET/CT represents a preoperative, non-invasive tool that when combined with sonographic features can identify indeterminate nodules at low risk for malignancy.