ObjectiveTo evaluate the diagnostic performance of different ultrasound sections of thyroid nodule (TN) using computer-aided diagnosis system based on artificial intelligence (AI-CADS) in predicting thyroid malignancy.Materials and methodsThis is a retrospective study. From January 2019 to July 2019, patients with preoperative thyroid ultrasound data and postoperative pathological results were enrolled, which were divided into two groups: lower risk group (ACR TI-RADS 1, 2 and 3) and higher risk group (ACR TI-RADS 4 and 5). The malignant risk scores (MRS) of TNs were obtained from longitudinal and transverse sections using AI-CADS. The diagnostic performance of AI-CADS and the consistency of each US characteristic were evaluated between these sections. The receiver operating characteristic (ROC) curve and the Cohen κ-statistic were performed.ResultsA total of 203 patients (45.61 ± 11.59 years, 163 female) with 221 TNs were enrolled. The area under the ROC curve (AUC) of criterion 3 [0.86 (95%CI: 0.80~0.91)] was lower than criterion 1 [0.94 (95%CI: 0.90~ 0.99)], 2 [0.93 (95%CI: 0.89~0.97)] and 4 [0.94 (95%CI: 0.90, 0.99)] significantly (P<0.001, P=0.01, P<0.001, respectively). In the higher risk group, the MRS of transverse section was higher than longitudinal section (P<0.001), and the agreement of extrathyroidal extension and shape was moderate and fair (κ =0.48, 0.31 respectively). The diagnostic agreement of other ultrasonic features was substantial or almost perfect (κ >0.60).ConclusionThe diagnostic performance of computer-aided diagnosis system based on artificial intelligence (AI-CADS) in longitudinal and transverse ultrasonic views for differentiating thyroid nodules (TN) was different, which was higher in the transverse section. It was more dependent on the section for the AI-CADS diagnosis of suspected malignant TNs.

Objective:To explore the feasibility of deep learning-based restoration of obscured thyroid ultrasound images.Methods:A total of 358 images of thyroid nodules were retropectively collected from January 2020 to October 2021 at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, and the images were randomly masked and restored using DeepFillv2. The difference in grey values between the images before and after restoration was compared, and 6 sonographers (2 chief physicians, 2 attending physicians, 2 residents) were invited to compare the rate of correctness of judgement and detection of image discrepancies. The ultrasound features of thyroid nodules (solid composition, microcalcifications, markedly hypoechoic, ill-defined or irregular margins, or extrathyroidal extensions, vertical orientation and comet-tail artifact) were extracted according to the Chinese Thyroid Imaging Reporting and Data System (C-TIRADS). The consistency of ultrasound features of thyroid nodules before and after restoration were compared.Results:The mean squared error of the images before and after restoration ranged from 0.274 to 0.522, and there were significant differences in the rate of correctness of judgement and detection of image discrepancies between physicians of different groups(all P<0.001). The overall accuracy rate was 51.95%, the overall detection rate was 1.79%, there were significant differences also within the chief physicians and resident groups (all P<0.001). The agreement rate of all ultrasound features of the nodules before and after image restoration was higher than 70%, over 90% agreement rate for features such as solid composition and comet-tail artifact. Conclusions:The algorithm can effectively repair obscured thyroid ultrasound images while preserving image features, which is expected to expand the deep learning image database, and promote the development of deep learning in the field of ultrasound images.

Abstract The clinical data of 15 cases that planned to receive totally laparoscopic associating liver partition and portal vein ligation for staged hepatectomy were retrospectively collected. Before the stage 1 operation, the size and number of the tumors in future liver remnant (FLR) and the presence of cancer embolus in the portal vein were assessed using contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT). Before the stage 2 operation, CEUS was performed to assess the presence of traffic blood flow between the diseased liver and FLR after round-the-liver ligation. Before the stage 1 operation, 5 cases with tumors in FLR were found by CEUS and 6 cases were found by CECT (P > 0.05). Similarly, CEUS found 5 cases with cancer thrombus in portal vein, and CECT found 7 cases (P = 0.500). The consistency between the 2 modalities was good (κ = 0.857, P < 0.05, κ = 0.727, P < 0.05, respectively). Before the stage 2 operation, CEUS confirmed that there were 7 cases without traffic blood flow between the diseased liver and FLR, and 3 cases with residual traffic blood flow. The daily growth rate of FLR in the group without traffic blood flow (mean rank = 7.00) was higher than that in the group with traffic blood flow (2.00) significantly (P < 0.05). Contrast-enhanced ultrasound is a promising application in the preoperative evaluation of totally laparoscopic associating liver partition and portal vein ligation for staged hepatectomy.

Background Hepatocellular carcinoma (HCC) is a commonly-seen cancer in the clinical setting. Laparoscopic hepatectomy (LH) and radiofrequency ablation (RFA) are used for the treatment of HCC, yet the effects and safety difference of LH and RFA for HCC treatment need further investigation. Methods This study was a retrospective study design. HCC patients treated with LH or RFA in our hospital were identified. All the patients underwent 2-year long follow-up. The characteristics and details of LH and RFA groups during hospitalization were collected and compared. The Kaplan-Meier method was used to calculate the cumulative survival, and the survival curve was drawn and compared. Results A total of 94 HCC patients were included. The duration of surgery, estimated intraoperative blood loss, pain score on the first day after surgery, time to get out of bed after operation, time to oral eating, aspartate transaminase (AST) on the second day after surgery, C-reactive protein (CRP) on the second day after surgery, total medical cost in RFA group were significantly less than that of LH group (all P<0.05). The incidence of abdominal infection and biliary fistula in RFA group were significantly less than that of LH group (all P<0.05), and there was no significant difference in the incidence of bleeding and pleural effusion between two groups (all P>0.05). The 2-year overall survival and recurrence-free survival of the two groups had no significant statistical difference (all P>0.05). Conclusions RFA and LH have similar effects in the treatment of small HCC. And RFA has the advantages of less trauma, shorter operation duration, and quick postoperative recovery.

2020 年 9月 2 日,全国医学专业学位研究生教育指导委员会医专业学位委[2020]7 号文件"关于调整优化临床医学专业学位领域设置的通知"指出:为优化临床医学专业学位类别下的领域设置,进一步做好与住院医师规范化培训(以下简称"住培")科目对接工作,畅通临床医学人才培养路径,经国务院学位委员会办公室商定,就临床医学专业学位下设领域进行调整,其中影像医学与核医学调整为超声医学、放射影像学、核医学三个领域,为了适应新的形势,现将超声医学科住院医师规范化培训教学方式做一探讨.

目的 观察甲状腺细针穿刺与超声弹性成像两种方法诊断甲状腺结节病变的影像学特点,并探讨其临床价值,为提高临床诊断提供理论依据.方法 回顾分析2019年5月至2020年5月医院收治的85例诊断为甲状腺结节患者的临床病例资料,所有患者均接受细针穿刺活检、超声弹性成像两种诊断方法,探讨两种诊断方法敏感度、特异度、准确率.结果 本研究中85个结节均成功取得细胞学病理标本、超声弹性成像确认,其中良性结节55个(55/85,64.71％),恶性结节30个(30/85,35.29％).甲状腺细针穿刺技术敏感度为(70.0％),弹性成像技术敏感度(60.0％),差异无统计学意义(P>0.05),而甲状腺细针穿刺的特异度(87.3％)、准确率(81.18％)显著高于弹性成像技术的特异度(40.0％)、准确率(47.06％)(P均<0.05).结论 细针穿刺用于甲状腺结节诊断,可显著提高诊断灵敏度、准确率,保证穿刺区域的典型性及准确性,诊断价值更高.

Abstract Background and Objective: Ultrasound (US) devices are often used in percutanous interventions. Due to their low image quality, the US image slices are aligned with pre-operative Computed Tomography/Magnetic Resonance Imaging (CT/MRI) images to enable better visibilities of anatomies during the intervention. This work aims at improving the deep learning one shot registration by using less loops through deep learning networks.Methods: We propose two cascade networks which aim at improving registration accuracy by less loops. The InitNet-Regression-LoopNet (IRL) network applies the plane regression method to detect the orientation of the predicted plane derived from the previous loop, then corrects input CT/MRI volume orientation and improves the prediction iteratively. The InitNet-LoopNet-MultiChannel (ILM) comprises two cascade networks, where an InitNet is trained with low resolution images toperform coarse registration. Then, a LoopNet wraps the high resolution images and result of the previous loop into a three channel input and trained to improve prediction accuracy in every loop. Results: We benchmark the two cascade networks on 1035 clinical images from 52 patients , yielding an improved registration accuracy with LoopNet. The IRL achieved an average angle error of 13.3° and an average distance error of 4.5 millimieter. It out-performs the ILM network with angle error 17.4° and distance error 4.9 millimeter and the InitNet with angle error 18.6° and distance error 4.9 millimeter. Our results show the efficiency of the proposed registration networks, which have the potential to improve the robustness and accuracy of intraoperative patient registration.

BACKGROUND AND OBJECTIVE:Liver tumor ablation is often guided by ultrasound (US). Due to poor image quality, intraoperative US is fused with preoperative computed tomography or magnetic tomography (CT/MR) images to provide visual guidance. As of today, the underlying 2D US to 3D CT/MR registration problem remains a very challenging task.METHODS:We propose a novel pipeline to address this registration problem. Contrary to previous work, we do not formulate the problem as a regression task, which - for the given registration problem - achieves a low performance regarding accuracy and robustness due to the limited US soft-tissue contrast and the inter-patient variability on liver vessels. Instead, we first estimate the US probe angle roughly by using a classification network. Given this coarse initialization, we then improve the registration by formulation of the problem as a segmentation task, estimating the US plane in the 3D CT/MR through segmentation.RESULTS:We benchmark our approach on 1035 clinical images from 52 patients, yielding average registration errors of 11.6° and 4.7 mm, which outperforms the state of the art SVR method[1].CONCLUSION:Our results show the efficiency of the proposed registration pipeline, which has potential to improve the robustness and accuracy of intraoperative patient registration.

Objective:To investigate the application value of the ultrasonic elastic tissue dispersion quantitative analysis technique in differentiating thyroid nodules.Methods:A total of 164 nodules in 143 patients with thyroid nodules were examined by elastography ultrasound at Sir Run Run Shaw Hospital of Zhejiang University School of Medicine from January to November 2014. Eleven parameters were obtained by the tissue dispersion quantitative analysis software. These parameters were compared between benign and malignant groups by Mann-Whitney U test. The correlations between all the parameters and the pathologic results of thyroid nodules were analyzed by Spearman analysis. The receiver operating characteristic(ROC) curve of the parameter with the highest correlation coefficient was constructed. The cut-off value was calculated. Results:All parameters except correlation (CORR) had statistically significant differences between the groups of benign and malignant thyroid nodules(all P<0.01). Moreover, except CORR, the other parameters were correlated with the pathologic results of thyroid nodules(all P<0.05), with the highest coefficient in area ration of low-strain region (%AREA)( r s=0.818). ROC curves were constructed to estimate the clinic values of %AREA in diagnosis of thyroid cancer, the area under ROC curve was 0.991 for %AREA, the cut-off point was 74.83%, the sensitivity and specifity was 98.1% and 89.8%, respectively. Conclusions:The tissue dispersion quantitative analysis technique has high value in the differential diagnosis of benign and malignant thyroid nodules.

In recent years, image-guided thermal ablations have become a considerable treatment method for cancer patients, including support through navigational systems. One of the most critical challenges in these systems is the registration between the intraoperative images and the preoperative volume. The motion secondary to inspiration makes registration even more difficult. In this work, we propose a coarse-fine fast patient registration technique to solve the problem of motion compensation. In contrast to other state-of-the-art methods, we focus on improving the convergence range of registration. To this end, we make use of a Deep Learning 2D U-Net framework to extract the vessels and liver borders from intraoperative ultrasound images and employ the segmentation results as regions of interest in the registration. After an initial 3D-3D registration during breath hold, the following motion compensation is achieved using a 2D-3D registration. Our approach yields a convergence rate of over 70% with an accuracy of 1.97+1.07 mm regarding the target registration error. The 2D-3D registration is GPU-accelerated with a time cost of less than 200 ms.

To evaluate the value of contrast-enhanced ultrasound (CEUS) technology for curative effect evaluation of intervention treatment in patients with primary liver cancer (PLC). All 94 patients accepted the treatment of transcatheter arterial chemoembolization (TACE) with CEUS detection. After TACE treatment, the evaluation results of CEUS detection were consistent with enhanced CT, and the positive rate of CEUS detection is higher, more sensitive, the total coincidence rate was 68.3%; evaluation results of CEUS detection were inconsistent with enhanced MRI, and the total coincidence rate was 96.0%. The sensitivity of CEUS, enhanced CT and MRI were 92.1%, 72.2% and 93.7%, respectively; the false negative rate were 4.8%, 10.3% and 4.0%,respectively; the total coincidence rate were 96.0%, 79.4% and 96.8%, respectively. The sensitivity, false negative rate and total coincidence rate of CEUS is obviously better than the enhanced. CEUS had curative effect evaluation after treatment in PLC patients.

患者女,38岁,孕3产1(剖宫产),因停经2个月伴腹痛至当地医院就诊,并住院治疗,入院后予米非司酮口服,后出现阴道出血,伴发热(体温38.0℃)、腹痛不适,行清宫术,术后患者阴道出血明显.实验室检查:血白细胞计数18.7×109/L(参考值4~10×109/L),血红蛋白 3.7 g/dl (参考值11~15 g/dl),中性粒细胞百分比92.3%(参考值55%~75%),C-反应蛋白:210.5 mg/L(参考值≤10 mg/L),遂予输血,并行子宫动脉栓塞术,术后阴道出血渐停止,但患者出现反复高热,体温最高39.4℃,伴腹胀、腹泻、气急不适,每日解水样便十余次,当地医院行胸部计算机断层扫描(computed tomography,CT)提示:两肺少许感染性病变,两肺下叶部分不张,两侧胸腔积液;腹部CT增强提示:子宫增大伴感染,考虑为子宫穿孔,腹、盆腔积液.当地医院予抗感染治疗,效果不佳,遂转浙江大学医学院附属邵逸夫医院.急诊查血白细胞计数 25.2×109/L,血红蛋白6.5 g/dl,中性粒细胞百分数 92.5%;为进一步诊治,收入院.妇科检查:外阴正常,阴道通畅,宫颈轻度靡烂,宫颈举痛,子宫前位,增大如孕4个月,双附件区无异常发现.彩色多普勒超声示:子宫明显增大,子宫大部分轮廓及子宫内膜显示不清,宫腔内可见大量含气性异常回声,后方结构显示不清,双侧卵巢显示不清(图1,2).增强CT示子宫腔明显增大,内密度不均匀,见较多积液积气,子宫底左前壁欠连续(图3),考虑子宫穿孔.临床初步诊断:(1)脓毒血症;(2)清宫术后宫腔内感染.

Objective: To investigate the occurrence of occult carcinoma in contralateral lobes based on the ultrasonic features of unilateral papillary thyroid carcinoma. Methods: The study included 202 consecutives cases of unilateral papillary thyroid carcinoma with benign nodules in the contralateral lobe identified by preoperative ultrasound or fine-needle aspiration from June 2014 to December 2015. All patients received total thyroidectomies, and with postoperative pathological examination they were divided into two groups, one including 60 cases with positive occult cancer and another one consisting of 142 cases with negative occult cancer. Univariate and multivariate analyses were performed to analyze the sonographic features of unilateral papillary thyroid carcinoma relevant to the occurrence of occult carcinoma in the contralateral nodules. Results: Univariate analysis indicated occult carcinoma in the contralateral lobes was associated with Hashimoto's thyroiditis(χ(2)=3.955, P=0.047), unclear border (χ(2)=4.375, P=0.036)and multifocality in the ipsilateral(χ(2)=7.375, P=0.007), but not with tumors maximum size, location, A/T, shape, internal structure, internal echo, acoustic halo, calcification, capsular invasion and blood flow signal in the lobe with carcinoma on another side. Multivariate analysis showed unclear border (OR=2.727, P=0.010) and multifocality in the ipsilateral(OR=2.807, P=0.005)of carcinoma were independent predictive factor for contralateral occult PTC. Conclusions: Unclear border and multifocality of PTC in the ipsilateral were closely relevant to the occurrence of occult carcinoma in the contralateral nodules.

Objective To investigate the application value of the ultrasonic elastic tissue dispersion quantitative analysis technique in different stages of subacute thyroiditis (SAT).Methods One hundred and forty-four SAT lesions detected from 81 patients were enrolled in the patient group.They were further divided into three subgroups,including acute group (group Ⅰ),medium group (group Ⅱ) and recovery group (group Ⅲ).Another 59 healthy volunteers were collected as control group.All the participants accepted conventional ultrasound and elastographic examinations.Eleven parameters were obtained by the tissue dispersion quantitative analysis software.These parameters were compared between groups and among subgroups by ANOVA.The correlation between all the parameters and the course of SAT were analyzed by Spearman and Multiple linear regression methods.Results Between groups and among subgroups,the complexity (COMP) and correlation (CORR) were not statistically different(all P ＞0.05).Differences of kurtosis (KURT) and angular secon moment (ASM) among the three subgroups were not significant (all P ＞0.05).Differences between groups and among subgroups were significantly different among the value of all the other seven indexes (all P ＜0.01).Moreover,they were all correlated with the clinical staging,with the highest coefficient in area ration of low-strain region (％ AREA)(r =-0.881).Regression model was constructed and only ％ AREA was selected into the regression equation.ROC curves were constructed to estimate the clinic value of ％ AREA in staging patients of SAT,the areas under ROC curves were0.986(group Ⅰ vs group Ⅱ-Ⅲ) and 0.988 (group Ⅰ-Ⅱ vs group Ⅲ[) for ％AREA,respectively.Conclusions The tissue dispersion quantitative analysis technique is helpful in estimating the stiffness of thyroid in patients with SAT.

Objective: To evaluate the diagnostic efficacies of BRAF(V600E) testing and Bethesda system for reporting thyroid cytopathology (BSRTC) in thyroid nodules with thyroid imaging reporting and data system (TIRADS) category 4 and 5. Methods: A total of 187 thyroid nodules in 187 patients underwent the examinations of ultrasound-guided fine needle aspiration cytology (FNAC) and BRAF(V600E) mutation were analyzed retrospectively. Receive operating characteristic (ROC) curve was used to investigate the diagnostic values of both methods and the clinical application of BRAF(V600E) combined with BSRTC was evaluated. SPSS17.0 software was used to analyze the data. Results: Among 187 thyroid nodules, 123 were malignant nodules confirmed with histopathological examination and 64 benign nodules determined by FNAC, histopathological examination, or long-term follow-up. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of BRAF(V600E) test were better than those of BSRTC [69.1%, 98.4%, 98.8%, 62.4%(χ(2)=77.3, P=0.000) vs 62.6%, 93.8%, 95.1%, 56.6%(χ(2)=54.4, P=0.000)]. While the sensitivity, specificity, PPV and NPV of the combined test of BRAF(V600E) and BSRTC for diagnosis of malignant thyroid nodules were 87.8%, 92.2%, 95.6%, 79.7%(χ(2)=112.6, P=0.000), respectively. The area under the ROC curve for the combined test was higher than that for each of tests (0.900 vs 0.858 or 0.838). Conclusions: The combined test of BRAF(V600E) mutation and BSRTC has a higher diagnostic efficacy for malignant thyroid nodules compared with BRAF(V600E) mutation or BSRTC alone.

Objective To evaluate the diagnostic value of ultrasound guided fine needle aspirate(FNA)and thyroglobulin measurement in fine-needle aspiration(FNA-Tg) for detecting lateral neck node metastasis in patients with thyroid carcinoma before thyroidectomy.Methods FNA and FNA-Tg for suspicious enlarged lymph nodes were performed.Postoperative pathologic results were taken as the gold standard.To obtain the optimal threshold value for diagnosis of FNA-Tg ROC curve,the diagnostic efficiency of FNA,FNA-Tg and the combination were compared.Results The best diagnostic threshold of FNA-Tg for suspicious metastatic lymph nodes was 26.5 μg/L,the Area under ROC curve of FNA-Tg was 0.916.When the FNA-Tg compared with FNA,the sensitivity and negative predictive value were statistically significant.When the combinaion diagnosis compared with single FNA,the sensitivity,accuracy and negative predictive value were statistically significant.Conclusions FNA-Tg is an important method for the diagnosis of metastatic lymph node.FNA-Tg raised the sensitivity,accuracy of FNA method and plays an important role in diagnosing metastatic lymph node via FNA.

Objective To investigate the diagnositc value of high frequency ultrasound guided fine needle aspirates (FNA) combined with washout fluid thyroglobulin (FNA-Tg) measurement for preoperative detecting lateral neck lymph node metastasis of thyroid carcinoma.Methods 205 preoperative patients with suspected metastatic lymph nodes were collected.All the patients were diagnoed as papillary thyroid cancer by FNA.They all underwent high frequency ultrasound guided fine-needle aspiration cytdogy,then Tg in FNA washout fluid (FNA-Tg) was measured.The histopathologic diagnosis for all of the suspected lymph nodes was obtained after lymphadenectomy.Results Of the 240 suspected lymph nodes 184 lymph nodes were positive by pathology,while 56 were negative.While 162 lymph nodes were diagnosed as positive metastasis and 78 as negative metastasis by FNA.The accuracy,sensitivity,specificity of FNA for assessing cervical metastatic lymph nodes were 87.5％,85.0％,92.8％,respectively.By FNA-Tg,168 lymph nodes were diagnosed as positive and 72 as negative metastasis.The accuracy,sensitivity,specificity of FNA-Tg for assessing cervical metastatic lymph nodes were 90.0％,89.1％,92.9％,respectively.Two-method combined,172 lymph nodes were diagnosed as positive metastasis and 68 as negative.The accuracy,sensitivity,specificity of FNA + FNA-Tg for assessing lateral neck metastatic lymph nodes were 95.0％,93.5％,100％,respectively.The accuracy rate of the the combined were higher than that of single diagnosis (x2 =8.454,P =0.004;x2 =4.324,P =0.038).Conclusions FNA and FNA-Tg combined are more sensitive and accurate in predicting lateral neck metastatic lymph nodes in preoperative PTC patients.

OBJECTIVE To investigate the value of thyroglobulin measurement in ultrasound guided fine-needle aspiration(FNA-Tg)for detecting neck node metastasis in patients with papillary thyroid carcinoma(PTC)after thyroidectomy. METHODS A total of 128 suspicious metastatic lymph nodes in 112 patients were retrospectively analyzed. Postoperative pathologic results were taken as the gold standard. The values of FNA and FNA-Tg combined FNA in the diagnosis of metastatic lymph nodes were compared with different ultrasonic features. RESULTS The sensitivity, specificity and accuracy of single FNA for the diagnosis of neck node metastasis were 67.5%, 98.0% and 79.7% respectively, and those of FNA-Tg combined FNA were 87.0%, 100.0% and 92.2% respectively. Compared with single FNA, the sensitivity and accuracy of FNA-Tg combined FNA were increased significantly(χ(2)=8.319, P=0.004; χ(2)=8.275, P=0.004). When the ultrasonographic characteristics met any one of five indicators for neck node metastasis, the sensitivity, specificity and accuracy of single FNA for the diagnosis of neck node metastasis were 38.1%, 95.7% and 68.2% respectively, and those of FNA-Tg combined FNA were 71.0%, 100.0% and 86.4% respectively. Compared with single FNA, the sensitivity and accuracy of FNA-Tg combined FNA were increased significantly(χ(2)=4.709, P=0.030; χ(2)=4.141, P=0.042). When the ultrasonographic characteristics met any two of five indicators for neck node metastasis, the sensitivity, specificity and accuracy of single FNA for the diagnosis of neck node metastasis were 55.0%, 100.0% and 73.5% respectively, and those of FNA-Tg combined FNA were 90.0%, 100.0% and 94.1% respectively. Compared with single FNA, the sensitivity and accuracy of FNA-Tg combined FNA were increased significantly(χ(2)=6.140, P=0.013; χ(2)=5.314, P=0.021). The ultrasonographic characteristics met any three, four or five of five indicators or did not meet any of the indicators, there was no significant difference in the value of the diagnosis of metastatic lymph nodes between single FNA and FNA-Tg combined FNA(P>0.05). CONCLUSIONS The combination of FNA with FNA-Tg could be helpful in diagnosis of lymph node metastasis. When the suspicious lymph nodes had one or two ultrasound characteristics for neck node metastasis, FNA-Tg could raise the sensitivity and accuracy of FNA, and FNA-Tg could not significantly improve in the diagnosis of FNA when presenting with no or with more than 2 ultrasonographic features.