Impact of Tumor Size on Prognosis in Differentiated Thyroid Cancer with Gross Extrathyroidal Extension to Strap Muscles: Redefining T3b.

The prognostic significance of tumor size in T3b differentiated thyroid cancer (DTC) remains debated and underexplored. This study aimed to examine the varying impact of T3b based on tumor size, analyzing disease-specific survival, disease-free survival, and overall survival. A retrospective review of 6282 DTC patients who underwent thyroid surgery at Seoul St. Mary's Hospital from September 2000 to December 2017 was conducted. T3b was classified into three subcategories, T3b-1 (≤2 cm), T3b-2 (2-4 cm), and T3b-3 (>4 cm), using the same size criteria for T1, T2, and T3a. T3b-1 showed no significant difference in disease specific survival compared to T1, and both disease-free and disease-specific survival curves were sequentially ranked as T1, T3b-1, T2, T3a, T3b-2, and T3b-3. The modified T category, reclassifying T3b-1 as T1, demonstrated superior staging performance compared to the classic T category (c-index: 0.8961 vs. 0.8959 and AUC: 0.8573 vs. 0.8518). Tumors measuring 2 cm or less within the T3b category may require downstaging, and a modified T category could improve the precision of prognostic staging compared to the current T category.

Current and Future of Robotic Surgery in Thyroid Cancer Treatment.

Thyroid cancer is among the most common endocrine malignancies, necessitating effective surgical interventions. Traditional open cervicotomy has long been the standard approach for thyroidectomy. However, the advent of robotic surgery has introduced new possibilities for minimally invasive procedures with benefits in terms of cosmetic outcomes, enhanced precision, comparable complication rates, and reduced recovery time. This study mainly reviewed the most widely used and well-known robotic thyroidectomy approaches: the transaxillary approach, the bilateral axillo-breast approach, and the transoral approach. This review examines the current status and future potential of robotic surgery in thyroid cancer treatment, comparing its efficacy, safety, and outcomes with those of conventional open cervicotomy. Challenges such as a longer operative time and higher costs exist. Future directions include technological advancements, tele-surgery, single-port surgery, and the integration of artificial intelligence. Robotic surgery holds promise in optimizing patient outcomes in thyroid cancer treatment.

Feasibility and Safety of transoral robotic parathyroidectomy: Initial experience with a new approach for parathyroid surgery.

BACKGROUND: We present the initial outcomes of transoral robotic parathyroidectomy (TORP) using the transoral vestibular approach in patients with primary hyperparathyroidism (PHPT). METHOD: A retrospective case series analysis was performed on patients diagnosed with PHPT between October 2016 and July 2019 who underwent transoral robotic surgery for parathyroidectomy. RESULTS: Thirteen patients (five males and eight females) successfully underwent TORP at our institution from October 2016 to July 2019. Eight patients underwent TORP alone, and five underwent TORP combined with transoral robotic thyroidectomy for papillary thyroid carcinoma. No intra- or postoperative complications were observed. Serum levels of parathyroid hormone, total calcium, and ionized calcium decreased to normal postoperatively and continued to decrease during the follow-up period. CONCLUSION: This study suggests that TORP holds promise for the treatment of patients with PHPT with the advantages of the robotic procedure, including dynamic visualization and meticulous dissection.

Safety and surgical outcomes of robotic adrenalectomy from a 15-year experience at a single institution.

Robotic adrenalectomy (RA) has gained significant popularity in the management of adrenal gland diseases. We report our experience at a single tertiary institution and evaluate the safety and surgical outcomes of RA. The data of 122 consecutive patients who underwent RA from October 2009 to December 2022 at Korea University Anam Hospital (Seoul, Korea) were reviewed. There were no perioperative complications. Clinicopathological features and surgical outcomes were retrospectively analyzed through complete chart reviews. Noteworthy findings include the influence of sex, tumor size, and body mass index on operation time, with the female and small tumor groups exhibiting shorter operation times (P = 0.018 and P = 0.009, respectively). Pheochromocytoma was identified as a significant independent risk factor for a longer operation time in the multivariate analysis [odds ratio (OR), 3.709; 95% confidence interval (CI), 1.127-12.205; P = 0.031]. A temporal analysis revealed a decreasing trend in mean operation times across consecutive groups, reflecting a learning curve associated with RA adoption. RA is a safe and effective operative technique alternative to laparoscopic adrenalectomy that has favorable surgical outcomes and enhances the convenience of the operation.

Overweight as a biomarker for concomitant thyroid cancer in patients with Graves' disease.

The incidence of concomitant thyroid cancer in Graves' disease varies and Graves' disease can make the diagnosis and management of thyroid nodules more challenging. Since the majority of Graves' disease patients primarily received non-surgical treatment, identifying biomarkers for concomitant thyroid cancer in patients with Graves' disease may facilitate planning the surgery. The aim of this study is to identify the biomarkers for concurrent thyroid cancer in Graves' disease patients and evaluate the impact of being overweight on cancer risk. This retrospective cohort study analyzed 122 patients with Graves' disease who underwent thyroid surgery at Seoul St. Mary's Hospital (Seoul, Korea) from May 2010 to December 2022. Body mass index (BMI), preoperative thyroid function test, and thyroid stimulating hormone receptor antibody (TR-Ab) were measured. Overweight was defined as a BMI of 25 kg/m² or higher according to the World Health Organization (WHO). Most patients (88.5%) underwent total or near-total thyroidectomy. Multivariate analysis revealed that patients who were overweight had a higher risk of malignancy (Odds ratios, 3.108; 95% confidence intervals, 1.196-8.831; p = 0.021). Lower gland weight and lower preoperative TR-Ab were also biomarkers for malignancy in Graves' disease. Overweight patients with Graves' disease had a higher risk of thyroid cancer than non-overweight patients. A comprehensive assessment of overweight patients with Graves' disease is imperative for identifying concomitant thyroid cancer.

Cost-Utility Analysis of Early Detection with Ultrasonography of Differentiated Thyroid Cancer: A Retrospective Study on a Korean Population.

BACKGRUOUND: There is debate about ultrasonography screening for thyroid cancer and its cost-effectiveness. This study aimed to evaluate the cost-effectiveness of early screening (ES) versus symptomatic detection (SD) for differentiated thyroid cancer (DTC) in Korea. METHODS: A Markov decision analysis model was constructed to compare the cost-effectiveness of ES and SD. The model considered direct medical costs, health outcomes, and different diagnostic and treatment pathways. Input data were derived from literature and Korean population studies. Incremental cost-effectiveness ratio (ICER) was calculated. Willingness-to-pay (WTP) threshold was set at USD 100,000 or 20,000 per quality-adjusted life year (QALY) gained. Sensitivity analyses were conducted to address uncertainties of the model's variables. RESULTS: In a base case scenario with 50 years of follow-up, ES was found to be cost-effective compared to SD, with an ICER of $2,852 per QALY. With WTP set at $100,000, in the case with follow-up less than 10 years, the SD was cost-effective. Sensitivity analysis showed that variables such as lobectomy probability, age, mortality, and utility scores significantly influenced the ICER. Despite variations in costs and other factors, all ICER values remained below the WTP threshold. CONCLUSION: Findings of this study indicate that ES is a cost-effective strategy for DTC screening in the Korean medical system. Early detection and subsequent lobectomy contribute to the cost-effectiveness of ES, while SD at an advanced stage makes ES more cost-effective. Expected follow-up duration should be considered to determine an optimal strategy for DTC screening.

Diagnostic utilities of washout CYFRA 21-1 combined with washout thyroglobulin for metastatic lymph nodes in thyroid cancer: a prospective study.

Cervical lymph node (LN) metastasis is common in differentiated thyroid cancer (DTC). This study evaluated the utility of the washout CYFRA 21-1 level, combined with the thyroglobulin (Tg) concentration, in terms of diagnosis of LN metastasis. We prospectively enrolled 53 patients who underwent thyroid surgery to treat DTC with lateral cervical LN metastases. Preoperative ultrasound guided needle localization was used to surgical sampling of specific LNs during the operation. The intraoperative washout Tg and CYFRA 21-1 levels were measured in such LNs. The Tg and CYFRA 21-1 levels differed significantly between metastatic and benign LNs. The cutoff values were 2.63 ng/mL for washout CYFRA 21-1 and 22.62 ng/mL for Tg. Combined use of the washout Tg and CYFRA 21-1 levels afforded the highest diagnostic accuracy (92.5%), better than that of individual markers. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were 94.6%, 90.0%, 91.4%, 93.8%, respectively. The conjunction of the washout CYFRA21-1 and Tg levels enhances the diagnostic accuracy of LN metastasis in DTC patients. The washout CYFRA 21-1 level may be useful when malignancy is suspected, especially in cases where the cytology and washout Tg findings do not provide definitive results.

Cost-effectiveness of intraoperative neural monitoring of recurrent laryngeal nerves in thyroid lobectomy for papillary thyroid carcinoma.

Purpose: Recurrent laryngeal nerve injury after thyroid surgery may cause vocal cord palsy (VCP), which leads to unexpected additional costs. In recent years, intraoperative neural monitoring (IONM) has been used to lower the incidence rate of VCP. This study aimed to analyze postoperative management costs for patients with papillary thyroid carcinoma (PTC). Methods: We analyzed the medical records of patients who underwent lobectomy for PTC from September 2018 to August 2019 at The Catholic University of Korea, Seoul St. Mary's Hospital. A total of 411 patients were enrolled and all the patients had voice examinations. We investigated the total costs in the IONM and non-IONM groups during a maximum 1-year follow-up and calculated the additional costs due to VCP by subtraction of the mean values in each group. Results: The incidence rate of VCP was 3.9% (16 of 411). Extrathyroidal extension was related to VCP in Cox regression tests and accounted for 3.2% (13 of 411). VCP rate did not show a significant difference between the IONM and non-IONM groups (4.1% vs. 3.8%, P = 0.883). Total costs for postoperative management were higher in the IONM group than in the non-IONM group (US $328.2 ± $220.1 vs. $278.7 ± $141.4, P < 0.05). However, the additional costs due to VCP were significantly lower in the IONM group than in the non-IONM group ($474.1 ± $150.3 vs. $568.9 ± $367.6, P < 0.005). Conclusion: The use of IONM can mitigate the increase in costs by saving additional expenses associated with VCP.

The Effect of Thyroid Surgery on the Accuracy of Palpation-Based Cricothyroid Membrane Identification in Female Patients: A Prospective Observational Cohort Study.

Background and Objectives: This study examined how a history of thyroid surgery impacts the precision of cricothyroid membrane (CTM) identification through palpation (validated by ultrasound) in female patients visiting the operating room for surgeries unrelated to neck procedures. Materials and Methods: This prospective observational cohort study enrolled adult female patients undergoing elective non-neck surgery, dividing them into control (no thyroid surgery history; n = 40) and experimental (with thyroid surgery history; n = 40) groups. CTM identification was performed by palpation and confirmed via ultrasound. Results: There were no significant differences between two groups in the demographic characteristics of the patients. The success rate and accuracy of CTM identification through palpation were significantly higher in the control group compared to the experimental group (90% vs. 42.5%, respectively; p < 0.001). For female patients with a history of thyroid surgery, the sensitivity of successful CTM palpation was 42.5%, and the specificity was 10%. These figures are based on the calculated true positives (17), false positives (36), true negatives (4), and false negatives (23). Conclusions: Thyroid surgery history in female patients may hinder the accurate palpation-based identification of the CTM, suggesting a need for enhanced clinical practices and considerations during airway management training.

Re-do transoral robotic thyroidectomy is feasible: preliminary results of the surgical feasibility and efficacy of completion transoral robotic thyroidectomy: cohort study.

BACKGROUND: Transoral robotic thyroidectomy (TORT) has proven to be a safe and effective procedure with favourable surgical and cosmetic outcomes, but its application in completion thyroidectomy procedures remains to be established. In this study, the authors present our experience with completion TORT, assessing its surgical feasibility and efficacy. between February 2017 and August 2023. METHODS: The authors conducted a retrospective analysis of consecutive patients who underwent completion TORT after an initial TORT procedure between February 2017 and August 2023. RESULTS: A total of 10 patients (three males and seven females) were included in the study, with a mean age of 42.2±13.5 years. The indications for completion thyroidectomy included five cases of aggressive initial lesions and five cases of metachronous papillary thyroid carcinoma detected in the remnant lobe. The median interval between the initial and completion TORT procedures was 6.5 months. Flap dissection time showed no significant difference between the initial TORT and completion TORT operations (43.3±7.5 vs. 36.2±11.2, P =0.125). However, the mean console time (127.9±42.6 vs. 86.4±26.3 min, P =0.019) and mean total operation time (206.7±65.9 vs. 146.0±34.9 min, P =0.021) were significantly longer during the initial TORT procedure than during the completion TORT procedure. Two patients experienced transient hypoparathyroidism, which resolved within four weeks postoperatively. No other complications, such as vocal cord palsy, mental nerve injury, or bleeding, were observed. The median follow-up period was 21.5 months, and no recurrences were detected in any of the patients. CONCLUSIONS: Our study demonstrates that re-do TORT is feasible, showing excellent cosmetic results and minimal adverse effects. Completion TORT may be considered a viable option for selected patients who require completion thyroidectomy after an initial TORT procedure.

Safety and surgical outcomes of single-port trans-axillary robot-assisted thyroidectomy: Experience from a consecutive series of 300 patients.

Since the introduction of the single-port (SP) robotic system, SP trans-axillary robot-assisted thyroidectomy (SP-TART) has been performed. We aimed to evaluate the safety and surgical outcomes of SP-TART in a consecutive series of 300 cases. We analyzed 300 patients with thyroid disease who underwent SP-TART from October 2021 to May 2023 in St. Mary's Hospital in Seoul, Korea. We analyzed the patients' clinicopathological characteristics and perioperative outcomes according to surgical extent. Of the 300 cases analyzed, 250 patients underwent less than total thyroidectomy (LTT), 31 patients underwent total thyroidectomy (TT), and 19 patients underwent TT with modified radical neck dissection (TT c mRND). The mean operative times for LTT, TT, and for TT c mRND were 69.8 ± 23.6, 104.2 ± 30.7, and 223.7 ± 72.4 min, respectively. Complications, including postoperative bleeding, transient hypoparathyroidism, and vocal cord palsy, were observed in nine, six, and six LTT, TT, and TT c mRND cases. The SP-TART method is a safe and feasible surgical option with a short operative time, good surgical outcome, and excellent cosmetic results.

BRAFV600E Positivity-Dependent Effect of Age on Papillary Thyroid Cancer Recurrence Risk.

BRAFV600E positivity is associated with increased aggressiveness of papillary thyroid cancer (PTC), and age is an important prognostic factor. However, the association between age and BRAFV600E positivity and the recurrence risk has not been investigated. This study aimed to investigate the impact of age on recurrence between patients with BRAFV600E-positive and -negative PTC. Patients with PTC who underwent initial thyroid surgery between January 2010 and December 2018 at Seoul St. Mary's Hospital (Seoul, Republic of Korea) were retrospectively reviewed. The BRAFV600E-positive (n = 1768) and BRAFV600E-negative groups (n = 428) were divided into two subgroups: younger (<35 years) and older groups (≥55 years). In the BRAFV600E-positive group, the younger group exhibited higher lymphatic and vascular invasion rates, more positive lymph nodes, higher lymph node ratios, and higher recurrence rates than the older group (5.9% vs. 2.1%). Multivariate analysis revealed that age, lymphatic invasion, and N category were significant risk factors in the BRAFV600E-positive group. In the BRAFV600E-positive group, the younger group had a higher recurrence risk than the older group (OR, 2.528; 95% confidence interval, 1.443-4.430; p = 0.001). In the BRAFV600E-negative group, age had no impact on recurrence risk. These results contribute to tailored treatment strategies and informed patient management.

Identification of NIFTP-Specific mRNA Markers for Reliable Molecular Diagnosis of Thyroid Tumors.

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a low-risk thyroid tumor with a favorable prognosis. Nonetheless, differentiating NIFTP from other thyroid tumors remains challenging, necessitating reliable diagnostic markers. This study is aimed at discovering NIFTP-specific mRNA markers through RNA sequencing analysis of thyroid tumor tissues. We performed mRNA expression profiling for 74 fresh frozen thyroid tissue samples, including NIFTP and benign and malignant follicular-cell-derived tumors. NIFTP/malignant tumors showed 255 downregulated genes and 737 upregulated genes compared to benign tumors. Venn diagram analysis revealed 19 significantly upregulated and 7 downregulated mRNAs in NIFTP. Akaike information criterion analysis allowed us to select OCLN, ZNF423, LYG1, and AQP5 mRNA markers. We subsequently developed a predictive model based on logistic regression analysis using these four mRNAs, which we validated in independent samples (n = 90) using a qRT-PCR assay. This model demonstrated high accuracy in predicting NIFTP in discovery dataset (AUC (area under the receiver operating characteristic) = 0.960) and the validation dataset (AUC = 0.757). Our results suggest that OCLN, ZNF423, LYG1, and AQP5 mRNA markers might serve as reliable molecular markers for identifying NIFTP among other thyroid tumors, ultimately aiding in accurate diagnosis and management of NIFTP patients.

Cost-Effectiveness of Active Surveillance Compared to Early Surgery of Small Papillary Thyroid Cancer: A Retrospective Study on a Korean Population.

BACKGROUND: Recently, active surveillance (AS) has been introduced as an alternative to early surgery (ES) for the management of papillary thyroid microcarcinoma (PTMC), because of its indolent features and low mortality. However, its cost effects have not been determined and the findings of current studies differ, according to each country's medical system. METHODS: A Markov model was constructed to compare the cost-effectiveness of AS and ES, based on a reference case of a 40-year-old patient diagnosed with PTMC. Costs and transition probabilities were derived from previous clinical studies in Korean populations, and the incremental cost-effectiveness ratio (ICER) and net monetary benefit (NMB) were calculated. The willingness-to-pay (WTP) threshold was set at USD 100,000 per quality-adjusted life year (QALY) gained. Sensitivity analyses were conducted to address the uncertainties in the model's variables. RESULTS: From the base scenario, the cumulative costs and effectiveness were both higher in ES than AS. The ICER for ES, compared with AS, was USD 6,619.86/QALY, lower than the set WTP. The NMB difference between AS and ES increased across the stages (USD 5,980 at the first stage and USD 159,667 at the last stage). The ICER increased along with decreasing age and increasing cost of surgery. The higher the ES utility score and the lower that of AS, the more cost-effective ES, with WTP set at USD 30,000. CONCLUSION: In the current Korean medical system, ES is more cost-effective than AS. ES is more cost-effective as it is diagnosed at young age and followed-up for a long time.

Clinical Implication of Bilateral and Unilateral Multifocality in Papillary Thyroid Carcinoma: A Propensity Score-Matched Study.

Papillary thyroid cancer (PTC) is commonly characterized by multifocality, which is associated with aggressive features and a less favorable prognosis. The current study aimed to compare the clinicopathologic characteristics and long-term oncological outcomes of bilateral and unilateral multifocal PTC. The medical records of 1745 patients with multifocal PTC who underwent thyroid surgery at Seoul St. Mary's Hospital were retrospectively reviewed. The clinicopathological characteristics and recurrence rates were compared based on cancer laterality. Further, 357 patients who underwent total thyroidectomy were matched to investigate the recurrence risk and disease-free survival (DFS). Before propensity score matching (PSM), there was no significant difference in the recurrence rate between the bilateral and unilateral multifocal PTC groups. Cancer laterality was not a predictor of DFS based on the Cox regression analyses. However, after PSM, unilateral multifocality was associated with a significantly high risk of recurrence. Similarly, unilateral multifocality was associated with a significantly poor DFS based on the Kaplan-Meier analysis. Compared with bilateral PTC, unilateral multifocal PTC was associated with a poor DFS. A comprehensive preoperative examination should be performed to detect multifocality before the initial surgical intervention for optimal treatment. Postoperative short-term follow-up is recommended for unilateral multifocal PTC for recurrence surveillance.

Mouse Models to Examine Differentiated Thyroid Cancer Pathogenesis: Recent Updates.

Although the overall prognosis of differentiated thyroid cancer (DTC), the most common endocrine malignancy, is favorable, a subset of patients exhibits aggressive features. Therefore, preclinical models that can be utilized to investigate DTC pathogenesis and novel treatments are necessary. Various mouse models have been developed based on advances in thyroid cancer genetics. This review focuses on recent progress in mouse models that have been developed to elucidate the molecular pathogenesis of DTC.

Lymph Node Ratio Predicts Recurrence in Patients with Papillary Thyroid Carcinoma with Low Lymph Node Yield.

The American Thyroid Association risk stratification system suggests that having >5 metastatic lymph nodes (LNs) increase the recurrence risk in patients with papillary thyroid carcinoma (PTC). However, little is known about PTC with <5 harvested LNs. This study aimed to stratify patients with low-LN-yield (low-LNY) PTC based on lymph node ratios (LNRs). From 2007 to 2017, 6317 patients who underwent thyroidectomies were diagnosed with PTC at Seoul St. Mary's Hospital, and 909 patients with low LNYs were included in the study. Tumor recurrence was compared based on LNR. The LNR cutoff was determined using a receiver operating characteristic curve. Forty-six patients (5.1%) experienced recurrences over a mean follow-up period of 127.24 ± 33.6 months (range, 5-190 months). The cutoff for the low-LNR (n = 675) and high-LNR (n = 234) groups was 0.29 (AUC = 0.676, 95% CI = 0.591-0.761, p < 0.001). The recurrence rate was significantly higher in the high-LNR group compared to the rate in the low-LNR group (12.4% vs. 2.5%, p < 0.001). Multivariate analysis using Cox regression revealed that tumor size and LNR ≥ 0.29 were independent prognostic factors for recurrence. Therefore, LNR can be utilized to stratify the risk of recurrence in patients with low-LNY PTC.

Persistent subjective voice symptoms for two years after thyroidectomy.

BACKGROUND: Voice change after thyroidectomy is an important issue in thyroid surgery. However, little is known about long-term voice outcomes after thyroidectomy. This study investigates the long-term voice outcomes of thyroidectomy up to two years after surgery. Also, we analyzed the pattern of recovery through acoustic tests over time. METHODS: We reviewed data from 168 patients who underwent thyroidectomy between January 2020 and August 2020 at a single institution. The Thyroidectomy-related Voice and Symptom Questionnaire (TVSQ) score and acoustic voice analysis results were examined preoperatively and postoperative one, three, and six months, and one and two years after surgery. We divided patients into two groups based on the TVSQ score (≥15 or <15) at two years postoperatively. We investigated the difference of acoustic characteristics between the two groups and analyzed correlations between acoustic parameters and various clinical and surgical factors. RESULTS: Voice parameters tended to recover, but some parameters and TVSQ scores exhibited deterioration two years after surgery. In the subgroups, among the many clinicopathologic factors examined, voice abuse history including professional voice users (p = 0.014), greater extent of thyroidectomy and neck dissection (p = 0.019, p = 0.029), and high pitch voice (F0; p = 0.005, SFF; p = 0.016) were associated with high TVSQ score at two years. CONCLUSIONS: Patients frequently experience voice discomfort after thyroidectomy. After surgery, voice abuse history including professional voice users, greater extent of surgery, and higher pitch voice are associated with worse voice quality and increased risk of persistent voice symptoms over the long-term.

Clinical Significance of the Lymph Node Ratio of the Second Operation to Predict Re-Recurrence in Thyroid Carcinoma.

The purpose of this study was to establish the risk factors for re-recurrences and disease-specific mortality (DSM) in recurrent thyroid cancer. Patients with recurrent thyroid cancer who underwent initial thyroid surgery from January 2000 to December 2019 at Seoul St. Mary's Hospital (Seoul, Korea) were assessed. Clinicopathological characteristics and long-term oncologic outcomes were compared between patients with one recurrence (n = 202) and patients with re-recurrences (n = 44). Logistic regression and cox-regression analyses were conducted to determine the risk factors for re-recurrences and DSM, respectively. Receiver-operating characteristic curve analysis was performed to determine the cutoff value for lymph node ratio (LNR) as a predictor of re-recurrences. DSM was significantly higher in the re-recurrence group compared with the single-recurrence group (6.8% vs. 0.5%, p = 0.019). Surgical treatment at the first recurrence significantly lowered the risk of re-recurrences. Age (≥55), male sex, and LNR (≥0.15) were independent significant risk factors for re-recurrences in patients who underwent surgery at the first recurrence. Surgical resection is the optimal treatment for initial thyroid cancer recurrence. LNR at re-operation is more effective in predicting re-recurrence than the absolute number of metastatic LNs.

Investigation of optimal convolutional neural network conditions for thyroid ultrasound image analysis.

Neural network models have been used to analyze thyroid ultrasound (US) images and stratify malignancy risk of the thyroid nodules. We investigated the optimal neural network condition for thyroid US image analysis. We compared scratch and transfer learning models, performed stress tests in 10% increments, and compared the performance of three threshold values. All validation results indicated superiority of the transfer learning model over the scratch model. Stress test indicated that training the algorithm using 3902 images (70%) resulted in a performance which was similar to the full dataset (5575). Threshold 0.3 yielded high sensitivity (1% false negative) and low specificity (72% false positive), while 0.7 gave low sensitivity (22% false negative) and high specificity (23% false positive). Here we showed that transfer learning was more effective than scratch learning in terms of area under curve, sensitivity, specificity and negative/positive predictive value, that about 3900 images were minimally required to demonstrate an acceptable performance, and that algorithm performance can be customized according to the population characteristics by adjusting threshold value.