Search Results (40)

Background and Objectives: Mean platelet volume (MPV) is a routinely available blood marker that measures platelet size and activation, and it has been evaluated as a potential marker for thyroid malignancies. Platelets participate in tumor genesis through angiogenesis, immune evasion, and metastasis, making them plausible adjuncts for cancer risk evaluation. The objective is to systematically evaluate the role of MPV in thyroid cancers, with the main focus on diagnostic accuracy, prognostic value, and limitations, focusing on papillary thyroid carcinoma (PTC). Materials and Methods: A systematic search of PubMed was conducted from January 2015 to September 2025. Only free full-text studies on human subjects were included. Eligible studies included case–control, cohort, or observational designs reporting MPV or platelet indices in thyroid cancer compared with benign nodules or healthy controls. Data on diagnostic performance, associations with tumor stage, lymph node involvement, and recurrence were extracted and synthesized narratively. No formal risk-of-bias or study quality assessment tool was applied. The literature search was restricted to studies with freely available full-text articles, which may have introduced access-based selection bias. Results: Eleven studies met the inclusion criteria. Most of them reported high MPV values in papillary thyroid carcinoma (PTC), with limited evidence regarding other thyroid cancer subtypes. High values of MPC were reported in the majority of studies in PTC compared to benign nodules or healthy controls. The diagnostic performance of MPV alone was poor, but integration with inflammatory ratios such as the neutrophil-to-lymphocyte ratio (NLR) or platelet-to-lymphocyte ratio (PLR), and with ultrasound systems (TI-RADS), improved accuracy. Regarding prognostic utility, some studies linked higher MPV with lymph node involvement or recurrence risk, while others did not find significant data. Thyroid function, autoimmune thyroid disease, and methodological variability in MPV measurement limited comparability across studies. Conclusions: MPV is a low-cost adjunct biomarker, especially when combined with other hematologic and imaging markers. However, MPV should not be used as a stand-alone diagnostic or prognostic tool. Larger, prospective studies are mandatory to clarify its clinical role. Full article

Background/Objectives: Thyroid nodules are a prevalent condition with a high incidence rate of malignancy. Ultrasound (US)-based risk stratification systems have become widely utilized for the evaluation of thyroid nodules, including the American Thyroid Association (ATA) guidelines, the American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS), the Korean Society of Thyroid Radiology system (K-TIRADS), and the European Thyroid Association system (EU-TIRADS). Our institution has developed a real-time computerized score for evaluating thyroid nodules. This study aims to systematically compare the diagnostic performance of these systems when applied in real time by otolaryngologists, who integrate dynamic US imaging with physical examination. Methods: Patients with thyroid nodules who underwent US evaluation, US-guided fine-needle aspiration cytology (FNAC), and subsequent thyroidectomy were included. During each examination, otolaryngologists performed real-time risk categorization according to five US-based systems, with immediate scoring based on dynamic sonographic findings. Results: From April 2021 to November 2023, 130 patients were enrolled. For categories 4 and 5, the ATA guidelines had a sensitivity of 96.6% (95% CI: 87.3–100%), specificity of 78.9%, (60.6–97.3%) PPV of 84.6% (70.7–98.5%), NPV of 93.7% (81.9–100%), and accuracy of 88.1% (78.3–97.9%). The sensitivity of the ACR-TIRADS was 95.6% (87.3–100%), the specificity was 78.9% (60.6–97.3%), the PPV was 84.6% (70.7–98.5%), the NPV was 93.7% (81.9–100%), and the accuracy was 88.1% (78.3–97.9%). Both the K-TIRADS and the EU-TIRADS had sensitivities of 95.6% (87.3–100%), specificities of 78.9% (60.6–97.3%), PPVs of 84.6% (70.7–98.5%), NPVs of 93.7% (81.9–100%), and accuracies of 88.1% (78.3–97.9%). The computerized score (>3.3 considered malignant) and TBSRTC (Category 5 or 6) both had sensitivities of 73.9% (56.0–91.9%), specificities of 100%, PPVs of 100%, NPVs of 76.0% (59.3–92.7%), and accuracies of 85.7% (75.1–96.3%). Conclusions: Otolaryngologists can achieve highly accurate diagnostic performance when applying standardized ultrasound-based risk stratification systems, and a real-time computerized scoring system provides highly specific supplemental value for immediate clinical decision-making. Full article

Background: There is an ongoing project to create an international Thyroid Imaging Reporting And Data System (I-TIRADS) to harmonize the terminology of guidelines for reporting thyroid ultrasonography. As artificial intelligence (AI) has been gaining increasing attention also in the thyroid field, achieving solid information about the consistency of AI in interpreting the TIRADS terminology is relevant before the I-TIRADS is published. The present study aimed to examine the issue of AI when interpreting the TIRADS terminology to describe thyroid nodules (TNs). Methods: Three TIRADSs from the USA (ACR-TIRADS), Europe (EU-TIRADS), and Asia (K-TIRADS) were considered. The most popular AI, such as ChatGPT, was tested. All possible combinations of terms of the three TIRADSs were performed. Results: 2592 cases were included. With the ACR-TIRADS lexicon, there was a slightly significant difference between systems (p = 0.0494) which was attributed to variations between ACR- and EU-TIRADS (p = 0.0099). With the EU-TIRADS lexicon, there was a significant difference between systems (p < 0.0001) with a significant result between EU- and ACR-TIRADS (p = 0.0003). Using the K-TIRADS terminology, no significant difference was observed (p = 0.7954). The intraobserver agreement of ChatGPT was moderate with the best values (from 0.55 to 0.60) with the K-TIRADS lexicon. Conclusions: ChatGPT interprets the TIRADS lexicon but with variations when it is asked to assess TNs according to one TIRADS using the terminology of another TIRADS. Clinical operators as well as patients should also be aware of these novel data. Full article

Purpose: This study aimed to compare: the performance of K-TIRADS, EU-TIRADS and ACR TIRADS when used by observers with different levels of experience compared with the gold standard of cytology, and to evaluate the diagnostic performance of CAD (computer-aided design) compared with TI-RADS systems. Methods and Materials: In total, 323 thyroid nodules were evaluated in patients who were candidates for needle aspiration. Three observers with different levels of experience evaluated the diagnostic accuracy of three risk stratification systems (ACR TI-RADS, EU-TIRADS and K-TIRADS) and CAD software (S-Detect, made by Samsung) in characterizing the nodules. The results were compared with cytology examination. All nodules were characterized in terms of shape, margins, composition, calcifications, size, echogenicity and microcalcifications, and by stratifying individual nodules by using the three TIRADS systems; then S-detect software was applied and the data were compared with each other and with the gold standard. Results: Through cytology, 308 benign and 33 malignant nodules were identified. ACR-TIRADS showed a sensitivity of 100%, a specificity of 86%, a positive predictive value of 43% and a negative predictive value of 100%. EU-TIRADS showed a sensitivity of 100%, a specificity of 79%, a positive predictive value of 33% and a negative predictive value of 100%. K-TIRADS showed a sensitivity of 100%, a specificity of 89%, a positive predictive value of 50% and a negative predictive value of 100%. S-Detect combined with EU-TIRADS showed a high agreement (>95%) with the gold standard. Conclusions: K-TIRADS’s positive predictive power was slightly better than the other TIRADS, suggesting greater accuracy in correctly diagnosing positive cases. S-DETECT combined with EU-TIRADS has similar results to S-Detect with ACR- and K-TIRADS in terms of sensitivity, specificity and negative predictive power. However, it has a slightly better positive predictive power, suggesting greater accuracy in correctly diagnosing positive cases than the ACR- and K-TIRADS classification systems. In general, S-Detect cannot yet be considered a substitute for the human observer but only as an important support for human evaluation and an excellent and fast help to provide a comprehensive and complete report. Clinical Relevance/Application: S-Detect is a valuable tool for characterizing thyroid nodules when integrated with radiologist evaluation. It is also an important support tool for less experienced observers. Particularly interesting is the approach of use in integrated combination of the K-TIRADS by the human observer with S-Detect using EU-TIRADS, which could increase the overall diagnostic efficiency of the systems. Full article

Objectives: Oncocyte-rich indeterminate thyroid nodules (O-ITNs) present diagnostic and management challenges due to overlapping features between benign and malignant lesions and differing cytological classifications. This study aimed primarily to assess the ultrasound (US) characteristics and US-based risk of O-ITNs using the American College of Radiology Thyroid Imaging Reporting And Data Systems (ACR TI-RADS). A secondary objective was to compare the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) and Italian Consensus for the Classification and Reporting of Thyroid Cytology (ICCRTC) cytological systems regarding classification and clinical management implications for O-ITNs. Methods: A retrospective study was conducted on 177 ITNs (TIR3A and TIR3B) evaluated between June 2023 and December 2024 at CTO-Alesini, Rome (Italy). Nodules were assessed with US, cytology, and histology. Oncocyte predominance was defined as >70% oncocytes on fine-needle aspiration (FNA). US features were analyzed according to ACR TI-RADS. Nodules were reclassified by BSRTC, and potential differences in clinical case management (CCM) were analyzed. Results: O-ITNs comprised 47.5% of the sample. Compared to non-O-ITNs, O-ITNs were larger and more frequently showed low-risk US features, including a higher prevalence of ACR TI-RADS 3 nodules. However, no progressive increase in the risk of malignancy (ROM) was observed across ACR TI-RADS classes within O-ITNs. Histological malignancy was identified in 47.1% of O-ITNs, a lower proportion compared to non-O-ITNs, though the difference was not statistically significant. Classification discordance with potential management impact was lower in O-ITNs (20.2%) than in non-O-ITNs (38.7%). Conclusions: O-ITNs typically exhibit benign-appearing US features and lower classification discordance between BSRTC and ICCRTC, yet US risk stratification fails to differentiate malignancy risk within O-ITNs. A tailored approach integrating cytology and cautious US interpretation is essential for optimal O-ITN management. Full article

Background and Objectives: Indeterminate thyroid nodules (Bethesda III and IV) are a common clinical entity that present a diagnostic challenge due to their intermediate risk of malignancy. This study aimed to evaluate the role of ultrasound in risk stratification and malignancy prediction to support clinical decision-making and reduce unnecessary surgical interventions. Materials and Methods: This retrospective multicenter cohort study included patients aged ≥18 years who underwent thyroid surgery between 2016 and 2022 at four centers in the Eastern Province of Saudi Arabia. Only nodules with indeterminate cytology (Bethesda III or IV) were included. Data collected included demographic characteristics, thyroid function, ultrasound features, cytology results, and histopathological findings. Results: A total of 679 patients with 733 nodules were reviewed. Of these, 206 patients with 223 indeterminate nodules were included (median age: 42 years; 88.3% female). The overall malignancy rate was 46.6%. Independent predictors of malignancy included solid hypoechoic composition (OR = 2.26, p = 0.012), microcalcifications (OR = 3.07, p = 0.002), lymph node involvement (OR = 2.43, p = 0.021), American Thyroid Association (ATA) intermediate to high suspicion category (OR = 1.9, p = 0.018), and Thyroid Imaging Reporting and Data Systems (TI-RADS) categories 4–5 (OR = 2.3, p = 0.003). Solid hypoechoic nodules showed 82.3% specificity and 63.0% positive predictive value (PPV); microcalcifications demonstrated 84.1% specificity and 68.4% PPV; lymph node involvement had 87.6% specificity and 68.9% PPV. The ATA and TI-RADS classifications showed higher sensitivity (63.5% and 68.0%, respectively), but lower specificity (53.1% and 52.8%, respectively). Conclusions: Ultrasound features, particularly solid hypoechoic composition, microcalcifications, and lymph node involvement, as well as ATA and TI-RADS classifications, were independent predictors of malignancy in indeterminate thyroid nodules. Although ATA and TI-RADS offered higher sensitivity, individual features demonstrated greater specificity and PPV. These findings support the use of ultrasound risk stratification to guide surgical decisions in high-risk cases and suggest that additional diagnostic evaluation may be appropriate for low-risk nodules. Full article

Background/Objectives: Thyroid nodules are commonly observed in neck ultrasonography. Most nodules are benign; hence, several nodules require biopsy to accurately identify the malignant ones. Numerous risk classification guidelines have been developed for thyroid nodules, varying in their indications for fine-needle aspiration biopsy (FNAB). The aim of this study is to evaluate the performances of three internationally recognized thyroid imaging reporting and data systems (TIRADS) for risk stratification of malignancy in comparison to one another. Methods: A total of 225 thyroid nodules with definitive FNAB cytology or histopathological diagnoses were included in this study. Various ultrasound (US) features were classified into categories based on three TIRADS editions. The guidelines were assessed regarding sensitivity, specificity, predictive values, and diagnostic accuracy to compare diagnostic value. Results: The American College of Radiology (ACR)-TIRADS demonstrated the best diagnostic accuracy (63.1%), the highest specificity (58.7%) and positive predictive value (36.3%), among three different TIRADS systems. Korean (K)-TIRADS exhibited the highest sensitivity (94.2%), negative predictive value (96.1%), and the most favorable negative likelihood ratio (0.13). The European (EU)-TIRADS had a sensitivity of 90.4%, specificity of 48.6%, and diagnostic accuracy of 58.2%, ranking between the other two guidelines across most parameters. Conclusions: The rigorous use of the guidelines established by each of the three TIRADS systems would have markedly reduced the number of FNABs performed. The comparison of the three guidelines in our study indicated that they are effective screening methods for identifying malignant thyroid nodules. Among them, K-TIRADS showed the most effective diagnostic performance in sensitivity, while ACR-TIRADS yielded the best specificity. Full article

Background/Objectives: Guidelines for the risk stratification of thyroid nodules are based on certain well-recognized sonographic features of nodules. However, significant variations in reported sensitivity and specificity values are observed due to the overlap of imaging characteristics between benign and malignant nodules. Additionally, differences in ultrasound (US) equipment and the varying experience levels of radiologists performing the imaging procedures contribute to these discrepancies. Inevitably, there are also interobserver differences. The aim of this study was to investigate interobserver agreement on these criteria using the international thyroid imaging reporting and data system (I-TIRADS) thyroid evaluation framework, independently assessed by three residents and one consultant. Methods: We included 393 patients who underwent ultrasound-guided fine needle aspiration biopsy (FNAB) within four months. In each case, longitudinal and transverse video images of the thyroid gland, neck chain, and biopsied nodules were recorded. The evaluations of the parameters defined in the I-TIRADS dictionary were then performed by a radiologist with 15 years of experience and radiology assistants with 3, 3, and 2 years of experience, respectively, blinded to the images, pathology data, and patient demographics. The parameters evaluated included composition, echogenicity, margin, direction of growth, calcification, extension beyond the thyroid, and lymph node. An interobserver comparison between the US lexicon classifications of thyroid nodules was then performed. Results: The results of our study showed that the highest level of consensus was observed in the ‘mixed predominantly cystic’ classification, indicating a solid consistency between the assessors (κ = 0.729). Conversely, the subcategories ‘Solid’, ‘Mixed Predominantly Solid’ and ‘Spongiform’ showed moderate agreement, while the “Pure Cyst” subcategory exhibited the lowest level of agreement among the assessors (κ = 0.292). Agreement among the three radiology assistants was strong concerning the evaluation of nodule composition, growth direction, and lymph node assessment. In contrast, a moderate level of consensus was noted regarding the assessment of extrathyroidal extension, margins, and echogenicity. Notably, the parameter exhibiting moderate agreement across all readers was the presence of echogenic foci or calcifications. Conclusions: the reproducibility observed in the parameters defined within the lexicon supports its potential to enhance consistency and interobserver agreement in thyroid nodule assessment. Full article

Objectives: The aim of this study was to investigate the preoperative clinical and hematologic variables, including the neutrophil-to-lymphocyte ratio (NLR), that can be used to predict malignancy in patients with atypia of undetermined significance (AUS) thyroid nodules; we further aimed to develop a machine learning-based prediction model. Methods: We enrolled 280 patients who underwent surgery for AUS nodules at the Wonju Severance Christian Hospital between 2018 and 2022. A logistic regression-based model was trained and tested using cross-validation, with the performance evaluated using metrics such as the area under the receiver operating characteristic curve (AUROC). Results: Among the 280 patients, 116 (41.4%) were confirmed to have thyroid malignancies. Independent predictors of malignancy included age, tumor size, and the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) classification, particularly in patients under 55 years of age. The addition of NLR to these predictors significantly improved the malignancy prediction accuracy in this subgroup. Conclusions: Incorporating NLR into preoperative assessments provides a cost-effective, accessible tool for refining surgical decision making in younger patients with AUS nodules. Full article

Background: Thyroid nodules are common yet remain a diagnostic challenge. While ultrasound and Thyroid Imaging Reporting and Data Systems (TIRADS) are accepted as standard, the use of thyroid scintigraphy in euthyroid patients is debated. The European Association of Nuclear Medicine advocates it, whereas the American Thyroid Association and European Thyroid Association do not. However, it has not been evaluated whether scintigraphy adds value to TIRADS in a multimodal approach. Our study addresses this gap by assessing the impact of integrated pertechnetate scintigraphy on TIRADS accuracy. Methods: The diagnostic performance of ACR-TIRADS, EU-TIRADS, pertechnetate scintigraphy, and multimodal models were retrospectively analyzed for 322 nodules (231 benign, 91 malignant) in 208 euthyroid patients with histopathology as a reference. Generalized estimating equations were used for statistical analysis. Results: On scintigraphy, 210 nodules were hypofunctional, 99 isofunctional, and 13 hyperfunctional. The AUC for thyroid scintigraphy, ACR-TIRADS, and EU-TIRADS were 0.6 (95% CI: 0.55–0.66), 0.83 (95% CI: 0.78–0.88), and 0.78 (95% CI: 0.72–0.83). Integrating scintigraphy with ACR-TIRADS and EU-TIRADS slightly increased diagnostic accuracy (AUC 0.86 vs. 0.83, p = 0.039 and AUC 0.80 vs. 0.78, p = 0.008) and adjusted the malignancy probability for intermediate risk TIRADS categories, with iso- or hyperfunctioning nodules in ACR-TIRADS-TR4 or EU-TIRADS-4 showing comparable malignancy probabilities as hypofunctioning nodules in TR3 or EU-TIRADS-3, respectively. Conclusions: Integrating thyroid scintigraphy with ACR- or EU-TIRADS moderately improves diagnostic performance, potentially benefiting management, especially in complex cases like multinodular goiter or indeterminate FNA. Further research is warranted to validate these findings and explore their clinical implications. Full article

The American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) stratifies patients with thyroid nodules for further evaluation. We evaluated the accuracy of this risk stratification and compared it with that of fine-needle aspiration cytology (FNAC) and final pathology. The nodules (n = 381) of 329 patients (mean age, 45.5 y; 251 female) who underwent thyroid surgery from January 2021 to September 2023 were retrospectively analyzed for the ACR TI-RADS, FNAC, and final pathology results. The nodules were categorized according to risk of malignancy as 75.9% ACR TI-RADS 5, 72.6% ACR TI-RADS 4, 38.9% ACR TI-RADS 3, and 33.3% ACR TI-RADS 2. Considering ACR TI-RADS 5 and 4 as high-risk categories, the sensitivity, specificity, positive-predictive value, and negative-predictive value of the ACR TI-RADS categories were 77.9%, 57.3%, 73.8%, and 62.8%, respectively. With both ACR TI-RADS and FNAC high-risk categories combined, the sensitivity and specificity improved to 82.4% and 58.6%, respectively. The ACR TI-RADS score effectively predicts malignancy in higher-risk categories; however, some malignant cases were found within lower-risk categories, implying the need for careful utilization of this system. Combining high-risk ACR TI-RADS and FNAC results improves the diagnostic accuracy of thyroid nodules. Confirmation from further prospective studies is required. Full article

Purpose: To evaluate the impact of video sequences (cine-loops) on the interobserver agreement (IOA) using risk stratification systems (RSSs) for thyroid nodules (TNs). Methods: Twenty TNs were randomly selected from a large database and evaluated by twelve experienced observers using five different RSSs (Kwak-, ACR-, EU-, Korean-TIRADS, ATA Guidelines). In the first step, the evaluation was conducted based on static ultrasound (US) images in two planes (“static”). Six months later, these cases were reevaluated by the same observers using video sequences in two planes (“cine-loops”). Fleiss’ kappa (κ) was calculated for the IOA analyses. Results: IOA on static was moderate with κ values of 0.46, 0.42, 0.40, 0.45, and 0.38 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively, while the IOA on cine-loops was fair with κ values of 0.41, 0.38, 0.37, 0.36, and 0.34 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively. The overall IOA was superior in static images versus cine-loops (p = 0.024). Among other findings, the subgroup analyses (related to age, gender, US certificates, number of thyroid US per week, and RSSs experience) particularly showed that the experience of the observers in using RSSs had a significant influence on the IOA. Conclusions: The overall IOA (all twelve observers and all five RSSs) was superior on static US images in comparison to cine-loops. Furthermore, the overall IOA of the five US features revealed superior κ values of the static images over cine-loops. However, this impact was significantly lower when the observers were highly experienced in the use of US RSSs of TNs. Full article

Thyroid Ultrasound (US) is the primary method to evaluate thyroid nodules. Deep learning (DL) has been playing a significant role in evaluating thyroid cancer. We propose a DL-based pipeline to detect and classify thyroid nodules into benign or malignant groups relying on two views of US imaging. Transverse and longitudinal US images of thyroid nodules from 983 patients were collected retrospectively. Eighty-one cases were held out as a testing set, and the rest of the data were used in five-fold cross-validation (CV). Two You Look Only Once (YOLO) v5 models were trained to detect nodules and classify them. For each view, five models were developed during the CV, which was ensembled by using non-max suppression (NMS) to boost their collective generalizability. An extreme gradient boosting (XGBoost) model was trained on the outputs of the ensembled models for both views to yield a final prediction of malignancy for each nodule. The test set was evaluated by an expert radiologist using the American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS). The ensemble models for each view achieved a mAP0.5 of 0.797 (transverse) and 0.716 (longitudinal). The whole pipeline reached an AUROC of 0.84 (CI 95%: 0.75–0.91) with sensitivity and specificity of 84% and 63%, respectively, while the ACR-TIRADS evaluation of the same set had a sensitivity of 76% and specificity of 34% (p-value = 0.003). Our proposed work demonstrated the potential possibility of a deep learning model to achieve diagnostic performance for thyroid nodule evaluation. Full article

Background: The European Thyroid Imaging and Reporting Data System (EU-TIRADS) aims to reduce the overdiagnosis of thyroid cancer (TC) by guiding the selection of nodules for fine-needle aspiration biopsy (FNAB). This study sought to validate EU-TIRADS nodule selection criteria using data from EUROCRINE, an extensive international endocrine surgery registry. Method: We reviewed indications for FNAB among patients with TC compared to those with benign disease who underwent surgery between March 2020 and March 2022, considering preoperative EU-TIRADS scores and dominant nodule size (FNAB is recommended in Category 5 (˃10 mm or ˂10 mm with suspicious lymph nodes), 4 (˃15 mm), and 3 (˃20 mm)). Patients were categorized into three risk groups: minimal risk (patients with papillary microcarcinoma), high risk (patients with pT3b stage or higher, pN1b, or pM1), and low–moderate risk (all other patients). We conducted a Receiver Operating Characteristic (ROC) analysis to assess the diagnostic accuracy of the EU-TIRADS. Results: We analyzed 32,008 operations. Approximately 68% of the surgical records included EU-TIRADS classifications. The EU-TIRADS exhibited diagnostic accuracy across high-volume sites, with a median ROC Area Under the ROC Curve (AUC) of 0.752, indicating its effectiveness in identifying malignancy. Among the cases, 7907 patients had TC. Notably, 55% of patients with TC underwent FNAB despite not initially meeting the EU-TIRADS criteria. These patients were distributed across the minimal- (58%), low–moderate- (36%), and high-risk (5.8%) categories. Of the patients with TC recommended for FNAB, 78% were deemed low–moderate risk, 21% high risk, and only 0.7% minimal risk. Conclusion: The EU-TIRADS offers effective preoperative malignancy risk stratification. Promoting the proper use of the EU-TIRADS in clinical practice is essential to mitigate the overdiagnosis and overtreatment of low-risk TC. Full article

This study aims to explore the feasibility of fine-needle aspiration biopsy (FNAB) under dual modal photoacoustic tomography(PAT)/ultrasound (US) imaging. A total of 25 patients who have thyroid nodules with thyroid imaging reporting and data system (TIRADS) 3 and 4 (malignant risk <85%) were recruited. The specimens obtained from the PAT/US-guided FNAB were collected for cytology analysis. Cytological diagnoses for the 25 patients were classified in perspective of the Bethesda system for reporting thyroid cytopathology diagnostic category (DC) I: 4%(1/25); DC II: 12% (3/25); DC III: 20% (5/25); DC IV: 8% (2/25); DC V: 32% (8/25); and DC VI: 24% (6/25). The DC I nodule exhibited inadequate cytology and had structural characteristic of predominant calcifications in PAT/US mapping. The DC V-VI nodules showed lower photoacoustic (PA) signals compared to the DC I-IV nodules. Regions with a high PA signal demonstrated a significant number of erythrocytes in FNAB cytology. Moreover, nodules with microcalcifications did not show a significant difference compared to their surroundings in the PA signal, while nodules with macrocalcifications gave higher PA signals compared to their surroundings. The conclusions are as follows: combining US with PAT can evaluate the structure and function of thyroid nodules in vivo. This study demonstrates that dual modal PAT/US imaging has the potential to be an effective clinical tool to guide FNAB of thyroid nodules. Full article