Artificial Intelligence Computer-Assisted Diagnosis for Thyroid Nodules: Comparison of Diagnostic Performance Using Original and Mobile Ultrasonography Images

Background and Objectives@#This study investigated whether an artificial intelligence computer-assisted diagnosis (AI-CAD) software recently developed in our institution named the Severance Artificial intelligence program (SERA) could show similar diagnostic performance for thyroid cancers using ultrasonographic (US) images from a mobile phone (SERA_M) compared to using images directly downloaded from the pictures archive and communication system (PACS) (SERA_P). @*Materials and Methods@#From October 2019 to December 2019, 259 thyroid nodules from 259 patients were included. SERA was run on original and mobile images to evaluate SERA_P and SERA_M. Nodules were categorized according to the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). To compare diagnostic performance, a logistic regression analysis was conducted using the Generalized Estimating Equation. The area under the curve (AUC) was calculated using the receiver operating characteristic (ROC) curve, and compared using the Delong Method. @*Results@#There were 40 cancers (15.4%) and 219 benign lesions (84.6%). The AUC and sensitivity of SERA_M (0.82 and 85%, respectively) were not statistically different from SERA_P (0.8 and 75%, respectively) (p=0.526 and p=0.091, respectively). The AUC of radiologists (0.856) was not significantly different compared to SERA_P and SERA_M (p=0.163 and p=0.414, respectively). The sensitivity of radiologists (77.5%) was not statistically different compared to SERA_P and SERA_M (p=0.739 and p=0.361, respectively). @*Conclusion@#AI-CAD software using pictures taken by a mobile phone showed comparable diagnostic performance with the same software using images directly from PACS.

Fine Needle Aspiration Cytology vs. Core Needle Biopsy for Thyroid Nodules:A Prospective, Experimental Study Using Surgical Specimen

Purpose@#To evaluate and compare the diagnostic outcomes of ultrasonography (US)-guided fine needle aspiration (FNA) and core needle biopsy (CNB) performed on the same thyroid nodule using a surgical specimen for direct comparison. @*Materials and Methods@#We included 89 thyroid nodules from 88 patients from February 2015 to January 2016. The inclusion criterion was thyroid nodules measuring ≥ 20 mm (mean size: 40.0 ± 15.3 mm). Immediately after surgical resection, FNA and subsequent CNB were performed on the surgical specimen under US guidance. FNA and CNB cytopathologic results on the specimen were compared with the surgical diagnosis. @*Results@#Among the 89 nodules, 30 were malignant and 59 were benign. Significantly higher inconclusive rates were seen in FNA for malignant than benign nodules (80.0% vs. 39.0%, p < 0.001). For CNB, conclusive and inconclusive rates did not differ between benign and malignant nodules (p = 0.796). Higher inconclusive rates were seen for FNA among cancers regardless of US features, and in the subgroup of size ≥ 40 mm (62.5% vs. 22.9%, p = 0.028). Eleven cancers were diagnosed with CNB (36.7%, 11/30), while none was diagnosed using FNA. @*Conclusion@#In this experimental study using surgical specimens, CNB showed a potential to provide improved diagnostic sensitivity for thyroid cancer, especially when a conclusive diagnosis is limited with FNA.

Core-Needle Biopsy Does Not Show Superior Diagnostic Performance to Fine-Needle Aspiration for Diagnosing Thyroid Nodules

Application of machine learning to ultrasound images to differentiate follicular neoplasms of the thyroid gland

Purpose@#This study was conducted to evaluate the diagnostic performance of machine learning in differentiating follicular adenoma from carcinoma using preoperative ultrasonography (US). @*Methods@#In this retrospective study, preoperative US images of 348 nodules from 340 patients were collected from two tertiary referral hospitals. Two experienced radiologists independently reviewed each image and categorized the nodules according to the 2015 American Thyroid Association guideline. Categorization of a nodule as highly suspicious was considered a positive diagnosis for malignancy. The nodules were manually segmented, and 96 radiomic features were extracted from each region of interest. Ten significant features were selected and used as final input variables in our in-house developed classifier models based on an artificial neural network (ANN) and support vector machine (SVM). The diagnostic performance of radiologists and both classifier models was calculated and compared. @*Results@#In total, 252 nodules from 245 patients were confirmed as follicular adenoma and 96 nodules from 95 patients were diagnosed as follicular carcinoma. As measures of diagnostic performance, the average sensitivity, specificity, and accuracy of the two experienced radiologists in discriminating follicular adenoma from carcinoma on preoperative US images were 24.0%, 84.0%, and 64.8%, respectively. The sensitivity, specificity, and accuracy of the ANN and SVM-based models were 32.3%, 90.1%, and 74.1% and 41.7%, 79.4%, and 69.0%, respectively. The kappa value of the two radiologists was 0.076, corresponding to slight agreement. @*Conclusion@#Machine learning-based classifier models may aid in discriminating follicular adenoma from carcinoma using preoperative US.

High Body Mass Index and Thyroid Stimulating Hormone Levels Do Not Affect Thyroid Nodule Selection for Fine-Needle Aspiration Biopsy after Ultrasound Evaluation

BACKGROUND AND OBJECTIVES: This study was to evaluate whether high body mass index (BMI) or thyroid stimulating hormone (TSH) level would affect selecting thyroid nodule for fine-needle aspiration biopsy (FNA) after ultrasound (US) evaluation. MATERIALS AND METHODS: A total of 3155 thyroid nodules (2159 benign and 996 malignant nodules) were included. Four grades of BMI and three levels of TSH were applied for grouping. US features of the thyroid nodules were divided into ‘probably benign’ and ‘suspicious for malignancy’ categories. Patients were grouped according to gender and univariate and multivariate logistic regression analysis were used to find the association between variables and malignancy. RESULTS: TSH levels were significantly higher in the malignant group (p<0.001). The grades of BMI did not show difference between the malignant and benign groups (females, p=0.074 and males, p=0.157). Younger age and ‘suspicious for malignancy’ US category were independent risk factors for malignancy in both genders. In females, a high TSH level (odds ratio=1.010, p<0.001) had significant association with malignancy. Except for younger age (odds ratio=0.998, p<0.001), no variable in nodules with ‘probably benign’ US category was significantly associated with malignancy. CONCLUSION: High TSH levels were more frequent in thyroid malignancy group, but neither high BMI nor high TSH level give additional information for FNA selection after US.

Preoperative High Neutrophil-Lymphocyte Ratio May Be Associated with Lateral Lymph Node Metastasis in Patients with Papillary Thyroid Cancers

BACKGROUND AND OBJECTIVES: The present study investigated the association between preoperative neutrophil-to-lymphocyte ratio (NLR) and poor prognostic outcomes in conventional papillary thyroid carcinomas (cPTCs). MATERIALS AND METHODS: Two hundred and five patients who underwent total thyroidectomy for cPTCs larger than 10 mm were evaluated retrospectively. Patients were classified into the low NLR (n=103) and high NLR (n=102) groups by the median NLR value (1.78) and logistic regression analysis was used to evaluate whether the NLR predicted aggressive PTC features. Patients were also classified into the disease-free (n=183) and persistence/recurrence (n=22) groups and Cox regression analysis was used to investigate factors affecting persistence/recurrence by Cox regression analysis. RESULTS: The high NLR group had a higher presence of lateral lymph node metastasis (p=0.004) and higher radioactive iodine doses (p=0.006) than the low NLR group. High NLR was an independent predictor of lateral lymph node metastasis (LNM) (OR, 2.786; p=0.005) but was not significantly associated with persistence/recurrence. CONCLUSION: Preoperative high NLR was an independent predictor of lateral LNM in cPTCs.

Associations between Bethesda categories and tumor characteristics of conventional papillary thyroid carcinoma

PURPOSE: The aim of this study was to investigate the associations of Bethesda categories III, V, and VI with the clinical and pathological features of thyroid nodules surgically confirmed as conventional papillary thyroid carcinomas (PTCs). METHODS: We analyzed 1,990 consecutive patients diagnosed with conventional PTC at surgery with preoperative Bethesda categories III, V, or VI. We determined the odds ratio (ORs) of the clinical and pathological variables associated with categories III and V, using category VI as the reference. RESULTS: Category III and V PTCs had a smaller pathological tumor size (OR, 0.934 and OR, 0.969, respectively) and less frequently had central lymph node metastasis (OR, 0.487 and OR, 0.780, respectively) than category VI PTCs. Category III PTCs less frequently showed suspicious ultrasonographic features (OR, 0.296) than category VI PTCs, and category V PTCs less frequently had gross extrathyroidal extension, with borderline significance (OR, 0.643; P=0.059). CONCLUSION: Conventional PTCs with a preoperative Bethesda category of III or V may less frequently exhibit poor prognostic factors than those with malignant cytology.

Ultrasonographic Evaluation of Diffuse Thyroid Disease: a Study Comparing Grayscale US and Texture Analysis of Real-Time Elastography (RTE) and Grayscale US

BACKGROUND AND OBJECTIVES: To evaluate and compare the diagnostic performances of grayscale ultrasound (US) and quantitative parameters obtained from texture analysis of grayscale US and elastography images in evaluating patients with diffuse thyroid disease (DTD). MATERIALS AND METHODS: From September to December 2012, 113 patients (mean age, 43.4±10.7 years) who had undergone preoperative staging US and elastography were included in this study. Assessment of the thyroid parenchyma for the diagnosis of DTD was made if US features suggestive of DTD were present. Nine histogram parameters were obtained from the grayscale US and elastography images, from which ‘grayscale index’ and ‘elastography index’ were calculated. Diagnostic performances of grayscale US, texture analysis using grayscale US and elastography were calculated and compared. RESULTS: Of the 113 patients, 85 (75.2%) patients were negative for DTD and 28 (24.8%) were positive for DTD on pathology. The presence of US features suggestive of DTD showed significantly higher rates of DTD on pathology, 60.7% to 8.2% (p0.05). CONCLUSION: Diagnostic performances were the highest for grayscale US features in diagnosis of DTD. Grayscale index may be used as a complementary tool to US features for improving sensitivity and NPV.

Metastatic renal cell carcinoma in the thyroid gland: ultrasonographic features and the diagnostic role of core needle biopsy

PURPOSE: The aims of this study were to present the ultrasonographic (US) features of metastatic renal cell carcinoma (RCC) in the thyroid gland and to evaluate the diagnostic utility of fineneedle aspiration (FNA) and core needle biopsy (CNB). METHODS: Eight patients with nine metastatic RCC nodules in the thyroid glands who were treated from January 2002 to March 2015 in a single tertiary hospital were consecutively selected and retrospectively reviewed. US features and clinical history were obtained from the institution's medical database. FNA was performed nine times on eight nodules and CNB was performed six times on six nodules. The diagnostic utility of FNA and CNB was evaluated. RESULTS: All nine nodules showed mass formation without diffuse thyroid involvement. On ultrasonography, metastatic RCC nodules were solid (100%), hypoechoic (100%), and oval-shaped nodules with a well-defined smooth margin (88.9%) and increased vascularity (100%, with 55% showing extensive vascularity). No calcifications were noted in any nodules. Lymph node metastasis and direct extension to nearby structures beyond the thyroid gland were not found. One FNA (11%) was able to confirm metastatic RCC, whereas all six CNBs confirmed metastatic RCC. CONCLUSION: Metastatic RCC appears as oval-shaped hypoechoic solid nodules with well-defined smooth margins, no calcifications, and increased vascularity on ultrasonography. Characteristic US features along with a previous history of RCC should raise clinical suspicion, and CNB should be performed to make an accurate diagnosis.

Risk of Thyroid Cancer in Euthyroid Asymptomatic Patients with Thyroid Nodules with an Emphasis on Family History of Thyroid Cancer

OBJECTIVE: To determine the factors associated with thyroid cancer, focusing on first-degree family history and ultrasonography (US) features, in euthyroid asymptomatic patients with thyroid nodules. MATERIALS AND METHODS: This retrospective study included 1310 thyroid nodules of 1254 euthyroid asymptomatic patients who underwent US-guided fine-needle aspiration biopsy between November 2012 and August 2013. Nodule size and clinical risk factors-such as patient age, gender, first-degree family history of thyroid cancer, multiplicity on US and serum thyroid stimulating hormone (TSH) levels-were considered together with US features to compare benign and malignant nodules. Multiple logistic regression analysis was performed to assess the risk of thyroid malignancy according to clinical and US characteristics. RESULTS: Although all of the clinical factors and US findings were significantly different between patients with benign and malignant nodules, a solitary lesion on US (p = 0.041-0.043), US features and male gender (p < 0.001) were significant independent risk factors for thyroid malignancy in a multivariate analysis. Patient age, a first-degree family history of thyroid cancer and high normal serum TSH levels did not independently significantly increase the risk of thyroid cancer. However, multicollinearity existed between US assessment and patient age, first-degree family history of thyroid cancer and serum TSH values. CONCLUSION: Ultrasonography findings should be the primary criterion used to decide the management of euthyroid asymptomatic patients with thyroid nodules. The concept of first-degree family history as a risk factor for thyroid malignancy should be further studied in asymptomatic patients.

Comparison of clinical characteristics of patients with acute kidney injury after intravenous versus inhaled colistin therapy

BACKGROUND: The aim of this study was to investigate the incidence and clinical characteristics of intravenous (IV) or inhaled (IH) colistin-associated acute kidney injury (AKI) using the Risk, Injury, Failure, Loss, End-stage Renal Disease criteria. METHODS: From 2010 to 2014, 160 patients were treated with IV or IH colistin. Of these, we included 126 patients who received colistin for > 72 hours for the treatment of pneumonia and compared the incidence and clinical characteristics of patients in the IV (n = 107) and IH (n = 19) groups. RESULTS: The patients included 104 men and 22 women, with a mean age of 69 years (range, 24–91 years). The mortality rate was 45%, and AKI occurred in 75 (60%) patients. At the end of therapy, the bacteriologic cure rate was 66%. There were no differences in the clinical characteristics between the IV and IH groups except for age. In comparison with patients in the IV group, the patients in the IH group were older (74 ± 8 vs. 68 ± 12 years, P = 0.026). The incidence of AKI was not different between the 2 groups (62 vs. 47%, P = not significant), and there was no difference in the severity of AKI according to the Risk, Injury, Failure, Loss, End-stage Renal Disease criteria. Of the 83 patients with AKI, 6 and 1 patients underwent renal replacement therapy, respectively. CONCLUSION: The incidence of AKI in patients with colistin therapy is 60% in our center. It seems that IH colistin therapy could not be better in safety than IV colistin therapy.

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Prognostic Impact of Ultrasonography Features and 18F-Fluorodeoxyglucose Uptake in Patients With Papillary Thyroid Microcarcinoma

OBJECTIVES: To evaluate the prognostic impact of ultrasonography (US) features and 18F-fluorodeoxyglucose (18F-FDG) uptake in patients with papillary thyroid microcarcinoma (PTMC). METHODS: This study included 74 patients with a single PTMC diagnosed pathologically. Patients underwent total thyroidectomy, or near-total thyroidectomy and staging thyroid US and positron emission tomography (PET) were performed prior to surgery. US features of thyroid nodules were reviewed retrospectively and the maximum standard uptake value (SUV) of nodules was semiquantitatively analyzed on 18F-FDG PET/computed tomography (CT). Patients were followed-up for recurrence, which was defined as PTC on cytology results, elevated serum thyroglobulin (Tg) or anti-Tg antibody levels, or uptake on whole-body scintigraphy. We used univariate and multivariate analyses to evaluate whether poor prognostic outcomes were associated with US features or SUV values derived from PET/CT of nodules. In addition, subjects were divided into 2 groups for subgroup analyses: one with nodules equal to or larger than 5 mm and one with nodules smaller than 5 mm. RESULTS: Among the 74 patients, there was no recurrence. Thus we evaluated the correlation between SUV value and US features with poor prognostic factors of PTMC which included extrathyroid extension, central and lateral lymph node (LN) metastasis. However no clinicopathologic factors were associated with extrathyroid extension, central LN metastasis, or lateral LN metastasis. CONCLUSION: In patients with PTMC, US features and SUV values on FDG-PET were not related to extrathyroid extension or LN metastasis. However, future studies with a larger sample size and longer follow-up should be performed to verify the results of this study.

Hyalinizing trabecular tumor of the thyroid: diagnosis of a rare tumor using ultrasonography, cytology, and intraoperative frozen sections

PURPOSE: The goal of this study was to evaluate the clinicopathological and imaging features of thyroid nodules surgically diagnosed as hyaline trabecular tumor (HTT), and to assess the role of cytology and frozen sections (FS) in the diagnosis of HTT. METHODS: This study included 21 thyroid nodules in 21 patients treated from August 2005 to March 2015 (mean age, 53.3 years) who were either diagnosed as HTT or had HTT suggested as a possible diagnosis based on cytology, FS, or the final pathology report. Patients' medical records were retrospectively reviewed for cytopathologic results and outcomes during the course of follow-up. Sonograms were reviewed and categorized. RESULTS: Twelve nodules from 12 patients were surgically confirmed as HTT. Ultrasonography (US)-guided fine needle aspiration (FNA) was performed on 11 nodules, of which six (54.5%) were papillary thyroid carcinoma (PTC) or suspicious for PTC and three (27.3%) were HTT or suspicious for HTT. Intraoperative FS suggested the possibility of HTT in seven nodules, of which four (57.1%) were confirmed as HTT. US-FNA suggested the diagnosis of HTT in 10 nodules, of which three (30.0%) were confirmed as HTT. Common US features of the 12 pathologically confirmed cases of HTT were hypoechogenicity or marked hypoechogenicity (83.4%), absence of calcifications (91.7%), parallel shape (100.0%), presence of vascularity (75.0%), and probable benignity (58.3%). CONCLUSION: HTT should be included in the differential diagnosis of solid tumors with hypoechogenicity or marked hypoechogenicity and otherwise benign US features that have been diagnosed as PTC through cytology.

The follicular variant of papillary thyroid carcinoma: characteristics of preoperative ultrasonography and cytology

PURPOSE: The goal of this study was to validate the ultrasonography (US) and cytopathological features that are used in the diagnosis of the follicular variant of papillary thyroid carcinoma (FVPTC) and to characterize the role of BRAF(V600E) mutation analysis in the diagnosis of FVPTC. METHODS: From May 2012 to February 2014, 40 thyroid nodules from 40 patients (mean age, 56.2 years; range, 26 to 81 years) diagnosed with FVPTC were included in this study. The US features of the nodules were analyzed and the nodules were classified as probably benign or suspicious for malignancy. Twenty-three thyroid nodules (57.5%) underwent BRAF(V600E) mutation analysis. Clinical information and histopathologic results were obtained by reviewing the medical records of the patients. RESULTS: Thirty nodules (75.0%) were classified as suspicious for malignancy, while 10 (25.0%) were classified as probably benign. Seven of the eight nodules (87.5%) with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) cytology showed suspicious US features, while one of the two nodules (50.0%) with follicular neoplasm cytology presented suspicious US features. Five of the 23 nodules (21.7%) that underwent BRAF(V600E) mutation analysis had positive results, all of which were diagnosed as suspicious for malignancy or malignant based on cytology. None of the nodules with benign, AUS/FLUS, or follicular neoplasm cytology were positive for the BRAF(V600E) mutation. CONCLUSION: US features allow nodules to be classified as suspicious for malignancy, and the presence of suspicious US features in nodules with ambiguous cytology may aid in the diagnosis of FVPTC. BRAF(V600E) mutation analysis is of limited value in the diagnosis of FVPTC.

Ultrasound-Guided Fine Needle Aspiration of Thyroid Nodules: A Consensus Statement by the Korean Society of Thyroid Radiology

Ultrasound (US)-guided fine needle aspiration (US-FNA) has played a crucial role in managing patients with thyroid nodules, owing to its safety and accuracy. However, even with US guidance, nondiagnostic sampling and infrequent complications still occur after FNA. Accordingly, the Task Force on US-FNA of the Korean Society of Thyroid Radiology has provided consensus recommendations for the US-FNA technique and related issues to improve diagnostic yield. These detailed procedures are based on a comprehensive analysis of the current literature and from the consensus of experts.

Effectiveness and Limitations of Core Needle Biopsy in the Diagnosis of Thyroid Nodules: Review of Current Literature

Fine needle aspiration (FNA) is currently accepted as an easy, safe, and reliable tool for the diagnosis of thyroid nodules. Nonetheless, a proportion of FNA samples are categorized into non-diagnostic or indeterminate cytology, which frustrates both the clinician and patient. To overcome this limitation of FNA, core needle biopsy (CNB) of the thyroid has been proposed as an additional diagnostic method for more accurate and decisive diagnosis for thyroid nodules of concern. In this review, we focus on the effectiveness and limitations of CNB, and what factors should be considered when CNB is utilized in the diagnosis of thyroid nodules.

Value of Additional von Kossa Staining in Thyroid Nodules with "Suspicious for Malignancy" on Cytology / 대한갑상선학회지

BACKGROUND AND OBJECTIVES: We investigated the clinical value of additional von Kossa staining in thyroid nodules with "suspicious for malignancy" on cytology. MATERIALS AND METHODS: From March 2010 to November 2010, 55 patients with 55 nodules which were diagnosed as "suspicious for malignancy" on cytology and had microcalcifications on ultrasound (US) underwent surgery and made up our final study population. We evaluated the role of the von Kossa stain as a preoperative diagnostic factor for thyroid cancer using histopathology as the "gold standard". Diagnostic performances were calculated of the presence of psammoma bodies on both cytology and the von Kossa staining and of US in predicting thyroid cancers. RESULTS: Of 55 nodules with microcalcifications on US and "suspicious for malignancy" on cytology, 53 (96.4%) were malignant and 2 (3.6%) were benign on histopathology. All pathologically benign nodules were negative on the von Kossa stain. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the von Kossa stain were 28.3%, 100%, 30.9%, 100%, and 5% for diagnosis, respectively. CONCLUSION: Von Kossa staining can be a valuable diagnostic tool in a thyroid nodule with "suspicious for malignancy" on cytology and microcalcifications on US, objectively.

Postoperative Surveillance of Thyroid Cancer: In View of a Radiologist / 대한갑상선학회지

Postoperative surveillance in patients with thyroid cancer is very important for radiologist to help the clinician manage the patient. The role of ultrasound is important but small volume tumor recurrence may not affect survival as well as its treatment may, at times, cause more morbid than its natural disease progression. In this review, I discuss postoperative surveillance in patients with thyroid cancer in the view of a radiologist.

Diagnostic Role of Conventional Ultrasonography and Shearwave Elastography in Asymptomatic Patients with Diffuse Thyroid Disease: Initial Experience with 57 Patients

PURPOSE: Thyroid ultrasonography (US) is a useful diagnostic tool in the evaluation of diffuse thyroid disease (DTD), whereas shearwave elastography is a dynamic technique that can provide information about tissue hardness by using acoustic shearwaves remotely induced by a focused ultrasonic beam. This study aims at investigating the role of conventional US and shearwave elastography in the diagnosis of asymptomatic patients with DTD. MATERIALS AND METHODS: Fifty-seven patients who underwent both conventional US and shearwave elastography were included in this study. Interobserver variability of the three radiologists in assessment of underlying thyroid echogenicity on conventional US was analyzed. Diagnostic performances for diagnosing DTD on conventional US and shearwave elastography were calculated and compared. RESULTS: Fair agreement was observed in the identification of DTD with conventional US (kappa value=0.27). The area under the receiver operating characteristic curve (Az) were 0.52-0.585 on conventional US by three radiologists. The Az values when using the mean and maximum elasticity values as a diagnostic criteria for DTD were 0.619 and 0.59 on shearwave elastography. Patients with DTD showed higher mean [24.1+/-10 kilo-Pascals (kPa)] and maximum (36.4+/-13.3 kPa) elasticity values on shearwave elastography when compared to the normal group (23.4+/-10.8 kPa and 33.7+/-12.4 kPa, respectively), although without statistical significance (p=0.802 and p=0.452, respectively). CONCLUSION: Conventional US did not show reliable interobserver agreement in the diagnosis of DTD. Although not statistically significant, shearwave elastography may provide additional information in the diagnosis of DTD. Therefore, larger prospective studies are needed to define the values of shearwave elastography for diagnosing DTD.