With the development of bioengineering technologies, medical ultrasound systems have evolved and advanced over the years, including the transition of ultrasound machines from analog devices to digital systems and improvements in transducer assembly from piezoelectric ceramics to single crystals. In the past several years, the further miniaturization of ultrasound units has become possible with the advancement of computer chip manufacturing and production. Most recently, a new handheld ultrasound system has been developed by the startup company Butterfly Network, using an innovative CMUT/CMOS-based probe technique. This paper will review the history, technology and features of this new device, as well as discuss its future potential as a personal sonoscope.

Artificial intelligence (AI) is an area of computer science that emphasizes the creation of intelligent software or system based on big data information, machine learning and deep learning technologies. The rapid development of science and technology as well as internet communication has enabled AI and big data to gradually apply to many fields of health care. The modern imaging medicine is one of the first areas where AI can play an important role and applications. As cross-sectional imaging, ultrasound (US) is well suitable for AI technology to standardize imaging protocols and improve diagnostic accuracy. This article reviews current AI technology and related clinical applications in the fields of thyroid, breast and liver US.

Advances in modern clinical ultrasound include developments in ultrasound signal processing, imaging techniques and clinical applications. Improvements in ultrasound processing include contrast and high-fidelity ultrasound imaging to expand B-mode imaging and microvascular (or microluminal) discrimination. Similarly, volumetric sonography, automated or intelligent ultrasound, and fusion imaging developed from the innate limitations of planar ultrasound, including user-operator technical dependencies and complex anatomic spatial prerequisites. Additionally, ultrasound techniques and instrumentation have evolved towards expanding access amongst clinicians and patients. To that end, portability of ultrasound systems has become paramount. This has afforded growth into the point-of-care ultrasound and remote or tele-ultrasound arenas. In parallel, advanced applications of ultrasound imaging have arisen. These include high frequency superficial sonograms to diagnose dermatologic pathologies as well as various intra-cavitary or lesional interrogations by contrast-enhanced ultrasound. Properties such as realtime definition and ease-of-access have spurned procedural and interventional applications for vascular access. This narrative review provides an overview of these advances and potential future directions of ultrasound.

Objectives: To investigate the causes, differential diagnosis, and clinical significance of absent blood flow (ABF) in the testis detected by color Doppler ultrasound (CDU) in acute scrotum.
Methods: A total of 263 patients with ABF in the testis detected by CDU in our hospital were reviewed retrospectively. However, only 111 patients who underwent surgery were included in this study. The ultrasonographic features of the testis and paratesticular tissue were analyzed. The surgical or surgical-pathologic results were taken as the reference standard to determine the causes of ABF in the testis.
Results: The causes of ABF in the testis were testicular torsion (n = 98, torsion group) and non-testicular torsion related diseases (n = 13, non-torsion group, including 8 testicular rupture, 3 epididymitis-orchitis combination with testicular necrosis, and 2 tumors). Tunica albuginea of the testis, diffuse enlarged epididymis, whirlpool sign, and internal echo of the testis were the better parameters for diagnosing the causes of ABF in the testis detected by CDU. And the accuracies of these approaches were 93.7%, 91%, 83.8%, and 81.1%, respectively. Whirlpool sign had a 100% positive predictive value (PPV), and disrupted tunica albuginea of the testis and diffuse enlarged epididymis each had 100% specificity for predicting testicular torsion. When the ultrasonographic findings were combined with these methods to determine the causes, the accuracy was 96.4% (107/111).
Conclusion: ABF in the testis detected by CDU is not always indicative of testicular torsion in acute scrotum; Analyzing ultrasound findings of the testis and paratesticular tissue can help with differential diagnosis of the causes of ABF in the testis and guide clinical decision-making.

With the rapid development of microelectronics, handheld ultrasound devices emerged and have a widespread use in the field of medicine and healthcare. The handheld ultrasound is a modality of medical ultrasonic device that is portable (i.e., carried by hand), easy to operate and in some cases even combine the scanner with the host system. It normally has the characteristics of light weight, small size and low power consumption. With the wireless imaging transmission technique, remote and intelligent diagnosis is possible for the doctors using handheld ultrasound devices. As soon as the low-cost, highperformance handheld ultrasound device was launched, it attracted clinical attention and received a warm welcome from primary doctors and clinicians, thereby accelerating the development of ultrasonic clinical visualization. In this paper, we will illustrate the status and roles of handheld ultrasound for its clinical settings and applications in the past, current, and future.

In 2009, Hitachi commercialized “Mappie^*1, the world’s first Capacitive Micro-machined Ultrasound Transducer (CMUT) using semiconductor based technology. It generated high quality diagnostic images of mammary glands, thanks to its broad-band characteristics^[1]. This year, the 4^th generation CMUT (4G CMUT) “SML44” has been brought to the market, achieved using advanced design and precise control of the fabrication process. When combined with new imaging technologies avail-able with the ARIETTA^*2 850, the SML44, in addition to excellent image quality, offers commonly used modalities and func- tions such as Tissue Harmonic Imaging (THI), Color Flow Mapping (CFM), Real-time Tissue Elastography^*3 (RTE), and Real-time Virtual Sonography^*4 (RVS). This report introduces the latest technology adopted in the 4G CMUT design.

Ultrasound (US) technology, with major advances and new developments, has become an essential and first-line imaging modality for clinical diagnosis and interventional treatment. US imaging has evolved from one-dimensional, two-dimensional to three-dimensional display, and from static to real-time imaging, as well as from structural to functional imaging. Based on its portability and advanced digital imaging technique, US was first adopted by emergency medicine in the 1980s and gradually gained popularity among other specialists for clinical diagnosis and interventional treatment. Point-of-Care Ultrasound (POCUS) was then proposed as a new concept and developed for new uses, which greatly extended clinical US applications. Nowadays, artificial intelligence (AI), cloud computing, 5G network, robotics, and remote technologies are starting to be integrated into US equipment. US systems have gradually evolved to an intelligent terminal platform with powerful imaging and communication tools. In addition, specialized US machines tend to be more suitable and important to meet increasing demands and requirements by various clinical specialties and departments. In this article, we review current US technology and POCUS as new concepts and its future trends, as well as related technological developments and clinical applications.

Objective: Thyroid nodules are a common medical problem in China and in other parts of the world. Many guidelines use ultrasound (US) as the first choice for evaluating thyroid nodules. A major limitation of US is operator dependency, resulting in a variety of discrepancies in diagnosing thyroid nodules in the literatures. Risk stratification of thyroid nodules is based on the patterns of US features in the 2015 American Thyroid Association (ATA) management guidelines for adult patients with thyroid nodules. We hypothesize that special training targeting features recognition may increase the inter-observer agreement.
Methods: The study was conducted on 52 participants from Peking Union Medical College Hospital (PUMCH) from March to May 2018.The participants were divided into two groups by their own decision for their convenience. Image featuresbased learning (IF-BL) was used to train the participants to learn special features including shape, margin, echo level, internal structure, calcification, vascularity through 10 standard images based on the 2015 ATA guideline. Group A (27 subjects) received IF-BL during the first month, and Group B (25 subjects) received IF-BL during the second month. All participants evaluated US features and risk stratification in 60 US images of 20 thyroid nodules before and after the training. The test results were graded by a teaching assistant according to the rule of 0.5 points assigned to every feature and 2 points assigned to risk stratification, with a total of 100 points. Inter-observer agreements of US features and risk stratification were assessed and compared before and after the training.
Results: After the first month, Group A had better scores than Group B, the control group of the month (75.4±9.4 vs 68.7±8.4, p = 0.01). At the end of the second month during which both groups were trained, there was no difference of scores between Group A and Group B (74.5±10.4 vs 75.1±7.4, P = 0.78). Scores of all participants were significantly higher than the initial (74.8±9.0 vs 65.8±13.6, P < 0.01). After the training, the kappa values of US features improved from 0.28-0.43 to 0.43-0.75, and those of risk stratification improved from 0.13 to 0.55.
Conclusion: IF-BL can effectively help trainees correctly recognize US features and evaluate the risk stratification of thyroid nodule and can improve the inter-observer agreement.

Many kinds of skin masses appeared as well-defined hypoechogenic lesion in ultrasound. Higher-frequency sound waves enable high resolution observation of the anatomical level and internal echogenic, In this study, 4 typical cases were observed by utilizing high resolution ultrasound (HRUS) at 10 to 20 MHz Ultrasound shows most Basal cell carcinoma (BCC ) was irregular-shaped while other kinds of cases appear as oval-shape, meanwhile, epidermoid cyst was located in the subcutaneous layer while the other three kinds of masses were located in the dermis. Color Doppler shows eccrine poromas and BCCs have flow signals, while dermatofibromas and eccrine poromas show a lack of vascularity. HRUS can provide noninvasive and effective diagnostic information for skin masses before surgery and can help the clinician evaluate whether the tumor was completely removed after surgery.

Contrast-enhanced ultrasound (CEUS) applications in cancer management have expanded over the past two decades. Through detection of vascularization and perfusion changes, CEUS provides a potentially reliable means of early prediction of response to different cancer therapies including systemic chemotherapy and locoregional therapies. Ultrasound-induced cavitation of contrast agents has a range of effects on the surrounding microenvironment. These effects can be manipulated to sensitize the tumors to radio- and chemotherapy, as well as achieve targeted delivery through drug-loaded contrast agents. Newer forms of drug carriers are being developed with improved drug-carrying capacity and tissue penetration. This review aims at providing a synopsis of the latest developments in CEUS’ use in oncologic therapy. While the majority of work described in this review is still in the pre-clinical phases, results have been encouraging and show potential translational benefit for cancer patients in the near future.

Ultrasound has developed as an invaluable tool in diagnosis and proper management in the intensive care unit (ICU). Application of critical care ultrasonography is quite distinct from the routine comprehensive diagnostic ultrasound exam, because the urgent setting mandates a goal-directed approach. Performing accurate and efficient critical care ultrasound requires ultrasound providers to first understand the pathophysiology of the disease and related imaging findings, and then follow the protocols to perform a focused ultrasound exam. In the ongoing coronavirus disease 2019 (COVID-19) pandemic, ultrasound plays an essential role in diagnosing and monitoring critically ill COVID-19 patients in the ICU. Our review focuses on the basics and clinical application of critical care ultrasound in diagnosing common lung disease, COVID-19 pulmonary lesions, pediatric COVID-19, and cardiovascular dysfunction as well as its role in ECMO and interventional ultrasonography.

The spread of new coronavirus (SARS-Cov-2) follows a different pattern than previous respiratory viruses, posing a serious public health risk worldwide. World Health Organization (WHO) named the disease as COVID-19 and declared it a pandemic. COVID-19 is characterized by highly contagious nature, rapid transmission, swift clinical course, profound worldwide impact, and high mortality among critically ill patients. Chest X-ray, computerized tomography (CT), and ultrasound are commonly used imaging modalities. Among them, ultrasound, due to its portability and non-invasiveness, can be easily moved to the bedside for examination at any time. In addition, with use of 4G or 5G networks, remote ultrasound consultation can also be performed, which allows ultrasound to be used in isolated medial areas. Besides, the contact surface of ultrasound probe with patients is small and easy to be disinfected. Therefore, ultrasound has gotten lots of positive feedbacks from the frontline healthcare workers, and it has played an indispensable role in the course of COVID-19 diagnosis and follow up.

By virtue of advantages including no exposure to radiation and low toxicity and side effects, hyperthermia has been increasingly applied in treating cancer and other diseases. However, the challenge of continuous temperature monitoring during hyperthermia limits its further application. Currently, temperature monitoring in the clinic is primarily carried out using invasive thermometry, which is hampered by incomplete detection and pain. To overcome the obvious limitations of invasive thermometry, a variety of noninvasive thermometry methods with suitable accuracy have been explored. Among these, ultrasonic thermal strain imaging (UTSI), which exploits the temperature dependence of ultrasonic echo time shift to form thermal strain images, shows significant potential. It not only possesses the merits of ultrasonography but also displays different tissue characteristics (thermal properties of tissue and sound velocity) from other ultrasound imaging methods, so it has been investigated extensively over the past few years. This paper reviews recent advances in UTSI for noninvasive thermometry and discusses its main limitations, hoping to show the strong clinical application potential of UTSI from solid basic theory and practical research results.

Objective: Ultrasonography is widely used for the diagnosis of many diseases including thyroid and breast cancers. Delineation of lesion boundaries from ultrasound images plays an important role in calculation of clinical indices and early diagnosis of diseases. However, accurate automatic segmentation of lesions is challenging because of their heterogeneous appearance and lack of background contrast.
Method: In this study, we employed a pre-trained deep convolutional neural network (PCNN) to automatically segment lesions from ultrasound images. Specifically, our PCNN based method used whole images of normal tissues and lesions as inputs and then generated the segmentation probability maps as outputs. A pre-training strategy was used to improve the performance of the PCNN based model. Additionally, we compared the performance of our approach with that of the common convolutional neural network segmentation methods on the same dataset.
Results: We validated on ultrasound images of thyroid nodules and breast nodules. The experimental results were shown in true positive rate (TP), false positive rate (FP), overlap metric (OM) and dice ratio (DR). Specifically, for thyroid nodule segmentation, our method could achieve an average of OM, DR, TP, FP as 0.8943, 0.9558, 0.9694, 0.0569 on overall folds, respectively. For breast nodule segmentation, our method could achieve an average of OM, DR, TP, FP as 0.8572, 0.9001, 0.9497, 0.8619, respectively.
Conclusion: Our proposed method is fully automatic without any user interaction and may be good enough to replace the timeconsuming and tedious manual segmentation approach, demonstrating the potential clinical applications.

Objective: This study evaluated the performance of automated machine-learning to diagnose non-alcoholic fatty liver disease (NAFLD) by ultrasound and compared these findings to radiologist performance.
Methods: 96 patients with histologic (33) or proton density fat fraction MRI (63) diagnosis of NAFLD and 100 patients without evidence of NAFLD were retrospectively identified. The “Fatty Liver” label included 96 patients with 405 images and the “Not Fatty Liver” label included 100 patients with 500 images. These 905 images made up a “Comprehensive Image” group. A “Radiology Selected Image” group was then created by selecting only images considered diagnostic by a blinded radiologist, resulting in 649 images. Cloud AutoML Visionbeta (Google LLC, Mountain View, CA) was used for machine learning. The models were evaluated against three blinded radiologists.
Results: The “Comprehensive Image” group model demonstrated a sensitivity of 88.6% (73.3-96.8%) and a specificity of 95.3% (84.2-99.4%). Radiologist performance on this image group included a sensitivity of 81.0% (74.3-87.6%) and specificity of 86.0% (72.6-99.5%). The model’s overall accuracy was 92.3% (84.0-97.1%), compared with mean individual performance (83.8%, 78.4-89.1%). The “Radiology Selected Image” group model demonstrated a sensitivity of 88.6% (73.3 - 96.8%) and specificity of 87.9% (71.8-96.6%). Mean radiologist sensitivity was 92.4% (86.9-97.9%) and specificity was 91.9% (83.4-100%). The model’s overall accuracy was 88.2% (78.1-94.8%) which was comparable to the individual radiologist performance (92.2%, 90.1-94.2%) and consensus performance (95.6%, 87.6-99.1%).
Conclusions: An automated machine-learning algorithm may accurately detect NAFLD on ultrasound.

Contrast-enhanced ultrasound (CEUS) is an imaging modality that has achieved considerable relevance in various clinical settings including the assessment of renal disease. CEUS is performed by injecting microbubble-based ultrasound contrast agents (UCAs) that create signals to display the microvasculature, allowing quantitative and qualitative assessment of parenchymal perfusion and real-time visualization of the renal anatomy. In recent years, CEUS has been widely accepted and applied for the assessment of kidney perfusion and the characterization of indeterminate renal masses, primarily due to its diagnostic efficacy, availability, low cost, reproducibility, and absence of nephrotoxicity. CEUS provides a higher spatial and temporal resolution than other cross-sectional imaging, resulting in high sensitivity and specificity for its applications in a variety of renal conditions including cancer monitoring following ablation, detection of transplant complications, hypoperfusion, acute traumatic injury, renal artery stenosis, parenchymal infection, and kidney intervention guidance. Additionally, the continuous investigation and development of new technologies surrounding this imaging technique have shown encouraging preliminary results for the use of CEUS in the evaluation of molecular expression in several disease processes, the dynamic analysis of blood flow kinetics, and the implementation of super-resolution imaging systems. The purpose of this article is to provide an overview of the current and potential clinical applications of renal CEUS.

Real-time ultrasound imaging has been used for the evaluation of pulmonary abnormalities and other complications during the outbreak of COVID-19. However, conventional ultrasound examination requires operators to conduct scanning either in the examination room or patient ward, which may increase the potential infective risk. Tele-operated ultrasound robotics can provide a unique technique for doctors to remotely scan patients. During the COVID-19 pandemic, we attempted to apply a 5G network-based scanning robot to conduct remote ultrasound examination on COVID-19 patients and to explore the feasibility of this technique for teleultrasound diagnosis and consultation during critical infectious situations.

Objective: To report our initial experience using the ultrasound (US)-guided single-needle lavage technique for treating calcific Achilles tendinitis.
Methods: Eighteen patients with chronic ankle pain refractory to medical treatment were treated percutaneously using a fine needle lavage technique under US guidance. Patients were evaluated using the visual analogue scale (VAS) pain score both before and 3 months after the procedure. Treatment-related complications were also recorded.
Results: All 18 cases of US-guided single-needle lavage were performed successfully. The range of recovery time was 30-45 days, and there was a significant reduction in the VAS pain score.
Conclusion: The US-guided single-needle lavage technique seems to be an effective and minimally invasive way to treat calcific Achilles tendinitis.

This case report describes a patient with severe coronavirus disease 2019 (COVID-19) concomitated with spontaneous pneumothorax, along with retrospective analysis of effective diagnosis and treatment. The case shows how chest radiography and computed tomography can play an important role in diagnosing and providing useful information for clinical management. The patient’s outcome and prognosis was related to his clinical management. In particular, early comprehensive treatment was certainly key to reducing complications and mortality in severe novel coronavirus pneumonia.

Objective: To investigate the value of lung ultrasound (LUS) in asymptomatic patients with confirmed COVID-19.
Methods: A retrospective analysis was performed on nine patients in a designated isolation hospital in Sanya from February 22nd, 2020 to February 23rd, 2020. All patients were confirmed with COVID-19 pneumonia by PCR test, but none had the typical symptoms of COVID-19. All patients first underwent LUS examination and then chest computed tomography (CT) scanning. The application value of LUS in asymptomatic confirmed patients with COVID-19 was evaluated, compared with chest CT which was regarded as the golden standard.
Results: Among nine asymptomatic patients with COVID-19, there were two cases (22.22%) with abnormal ultrasonic manifestations, of which one (11.11%) showed a fusion B3-line in zone 5 of the right lung, and the other showed localized pulmonary consolidation in zone 6 of the left lung. The remaining seven cases (77.78%) showed no abnormal changes in LUS, but only clear pleura sliding sign and A-line. Chest CT showed abnormal changes in three cases (33.33%). Two of them (22.22%) showed flocculent high-density shadow at the base of both lungs (especially in the right lung), while the other case showed ground-glass opacity with thickened interlobular septal in the left lower lobe, involving the pleura. There were no abnormalities on chest CT of the remaining six cases (66.67%). The two (22.22%) LUS-positive patients were in complete coincidence with CT-positive patients. This study showed that the coincidence rate of the two examination methods was 88.89%. Taking chest CT as golden standard, the sensitivity, specificity, positive predictive value, negative predictive value, and Kappa value of lung ultrasound in the diagnosis of COVID-19 were 66.67%, 100%, 100%, 85.71%, and 0.727, respectively.
Conclusion: LUS can evaluate lung lesions in asymptomatic patients with COVID-19. Compared with chest CT, the diagnostic coincidence rate and diagnostic consistency of LUS are relatively higher. For this asymptomatic type of patient, ultrasound can be used as a diagnosis method, which can avoid the risk of radiation exposure in a short period of time. As a rapid and dynamic assessment method, LUS can cooperate with remote consultation to provide timely and accurate guidance for clinical diagnosis and treatment when necessary.

Ultrasound is a commonly used imaging modality for breast cancer diagnosis and prognosis but suffers from false positives, false negatives and interobserver variability. Deep learning (DL), a subset of artificial intelligence, has the potential to improve the efficiency and accuracy of breast ultrasound. This article provides a comprehensive overview of DL applications for breast cancer diagnosis and treatment in ultrasound, including methodological descriptions of various DL models, and clinical applications on noise reduction, lesion localization, risk assessment, diagnosis, response evaluation and outcome prediction. Furthermore, the review highlights the importance of interpretability and small sample size learning of DL-based systems in clinical practice; specific recommendations for further expanding the clinical impact of DL-based systems are also provided.

An autonomous functioning thyroid nodule (AFTN) is a benign disease. It can autonomously secrete excessive thyroid hormones without the need for TSH stimulation. It is not subject to the hypothalamic-pituitary-thyroid axis and is rare during pregnancy. Here we report a case of a 36-year-old pregnant woman with hyperthyroidism detected in early pregnancy, According to ultrasound and laboratory results, she was diagnosed with an AFTN. Ultrasound-guided (US-guided) microwave ablation (MWA) was used to treat AFTN during the second trimester of pregnancy. Hyperthyroidism crisis and other complications did not occur due to MWA. Thyroid function was normal at 2, 3 and 4 months after MWA. The volume reduction rate (VRR) was 83.67% at 4 months after MWA. The patient gave birth normally at 40 weeks gestation. All indices of thyroid function were normal during postpartum and lactation. US-guided MWA is a feasible and safe method for the treatment of AFTN during pregnancy, specifically in the second trimester.

The purpose of this article is to review the use of lung ultrasonography (US) in the workup of COVID-19 pneumonia. The scanning protocol, normal US appearance of lung, major US features of COVID-19 pneumonia, diagnostic performance of lung US and potential pitfalls when explaining US results are descripted and discussed. Lung US is increasingly accepted as a useful tool in the workup of COVID-19 pneumonia. Certain US imaging features allow to confirm or rule out the diagnosis for clinical management; on other hand, most US findings are nonspecific with technical limitations. Thus, it is important to recognize these drawbacks since the ignorance of potential pitfalls of lung US may lead to over diagnosis or missed diagnosis.

Ultrasound imaging has attracted great interest of researchers due to their application in cancer diagnosis and treatment. Ultrasound contrast agents, microbubbles and nanobubbles are widely explored as a multifunctional platform, not only carrying other contrast agents for multimodal imaging to complement the disadvantages of each imaging modality, but also carrying drug/gene for cancer theragnostic. In this article, the characteristics and differences of microbubbles and nanobubbles are briefly introduced and reviewed. Besides, the microbubbles and nanobubbles driven multimodal imaging and theragnostic of cancer are summarized.

Objective: To explore the clinical value of ultrasonography for early detection and monitoring of angular pregnancy during the first-trimester.

Methods: For this retrospective study, we enrolled 23 patients with asymptomatic angular pregnancy who were diagnosed by ultrasound at early pregnancy and who underwent ultrasound follow-up to determine its clinical outcome. An ultrasound unit E8 (GE Healthcare, Milwaukee, WI) associated with a 5-9 MHz convex array transvaginal probe was used to image the gestational sac by both two-dimensional and three-dimensional modes. Transvaginal sonographic observation included the location, size, and shape of the gestational sac, as well as the relationship between the gestational sac and the endometrium. When the gestational sac was located close to or at the corners of the uterus, the wall thickness of the corner was measured and documented for follow-up during the first-trimester.

Results: Angular pregnancy (n=23) was detected by first ultrasonography at 37-50 days of gestation. All patients then underwent dynamic sonographic monitoring and were closely followed every 5-10 days for 1-3 weeks. In 3 cases, ultrasound showed embryo demise at follow-up examination. Seven cases were converted to intrauterine pregnancies based on sonographic findings and carried to term. In 13 cases, ultrasonography showed the gestational sacs grew outward in the corner of the uterus where the wall was thinning and had asymmetrical corners. Based on the ultrasound results, thesepregnancies were terminated (by surgery [n=6] or medication [n=7]).

Conclusions: Sonography is a valuable clinical tool for early detection and monitoring of angular pregnancy. Follow-up ultrasound can provide useful information for observing the transformation of angular pregnancy to guide clinical management, including whether to continue or terminate pregnancy.

Objectives: The size of cardiovascular structures in fetuses with congenital heart disease (CHD) is variable, and current reference structures used for comparative purposes are suboptimal: There are no known cardiovascular structures that are reliably normal in size. We sought to evaluate whether the aortic diameter at the diaphragmatic hiatus (ADDH) is affected in CHD.
Methods: The ADDH was evaluated by sonography in both study subjects (CHD group, n = 506) and age-matched normal controls (normal group, n = 506). The CHD group was divided into different subgroups according to evident anomalies in the cardiovascular system. ADDH differences between CHD subgroups and their controls were calculated with a paired Student's t-test. Possible sex differences were determined by an unpaired Student's t-test on the whole group.
Results: There were no significant differences in the ADDH between all CHD subgroups and age-matched controls (p > 0.05). No difference was found in the ADDH between female and male fetuses (p > 0.05).
Conclusion: The ADDH in fetuses with CHD is similar to that in controls. Hence, ratios between size of involved cardiovascular structures and ADDH may be a useful parameter for monitoring fetuses with CHD .

Protective measures that are needed when treating patients with highly contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) add difficulty when performing interventional procedures in isolation wards. We describe two cases of ultrasonography-guided nasogastric tube placement in severe COVID-19 patients, both disabled elderly patients who were unconscious and had complicated underlying diseases. The first is an 83-year-old patient with Alzheimer's, hemiplegia, and epilepsy; the second is a 67-year-old patient with hemiplegia and thoracic deformity. Nasogastric tube indwelling for severe patients like this was essential but challenging. With the help of ultrasonography, intubation proceeded successfully and rapidly. Operator’s confidence of appropriate placement was established because of definite tube visualization. These cases demonstrated that bedside ultrasonography in isolation wards can not only facilitate diagnosis but also assist interventional operations.

Objective: Preterm birth is still the leading cause of neonatal mortality. How to identify women who are at a higher risk of preterm birth continues to be one of the main problems in obstetrics. The aim of this study was to estimate the potential value of cervical strain in predicting the risk of preterm birth.
Methods: A total of 152 pregnant women who received prenatal examination in Beijing Obstetrics and Gynecology Hospital during January 2017 and October 2017. On the basis of the clinical diagnostic criteria for preterm birth, all of pregnant women were divided into two groups: There are 50 patients with the diagnosis of threatened premature or preterm labor in the study group and 102 patients without diagnosis of threatened premature or preterm labor in the control group. Measure cervical length by transvaginal ultrasound and obtain three cervical elasticity indexes by strain elastography: Closed internal cervical os strain rate, external cervical os strain rate and midpoint of the cervical canal strain rate. In the study group the pregnant women were divided into three teams: Length of cervix is 2 cm or less (10 cases) for T1, 2 to 3 cm (21 cases) for T2 and 3 cm or more (19 cases) for T3. Independent sample t-test was used to analyze the difference between the two groups. LSD-t test was used in the two groups. The receiver operating characteristic curve was used to analysis these four indicators. Statistical significance was defined as a p value < 0.05.
Results: Cervical length (CL) was lower and cervical os strain rate (CIS) was higher in the study group (2.67 ± 0.76 vs. 3.85 ± 0.65, p < 0.05; 0.53 ± 0.35 vs. 0.27 ± 0.24, p < 0.05). There was a significant difference with CIS in different cervical length team (p = 0.017) and the mean value of CIS in T1 was higher than the last two teams. The cutoff value of CL maximizing the accuracy of diagnosis was 3.2 cm; area under the curves (AUC), sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were 0.877, 73.3%, 87.0%, 82.2%, 73.5%, 86.4% respectively. Combining CL and CIS, the results of AUC, sensitivity, specificity, accuracy, PPV and NPV (0.891, 73.3%, 91.3%, 84.9%, 80.0%, 86.9%) increased in predicting the risk of spontaneous preterm birth, and the cutoff values of the CL and CIS were 3.1 cm and 0.35%.
Conclusion: The shortening of CL and the increasing CIS are closely related to the occurrence of premature birth and can be used as the indexes to predict the preterm labor. CIS can be used as an indicator to monitor early preterm changes. The combination of CL and CIS may have a role in assessing the risk of spontaneous preterm birth.

Application of thermal ablation therapy by using microwave or radiofrequency energy for benign thyroid nodules or/ and thyroid malignancies gets increased world-wide. Potential risks involved in the ablation procedure are not uncommon and could be catastrophic when out of control. Ablation for pharyngeal esophageal diverticulum’s (PED) being misdiagnosed as thyroid nodules constitutes the risks. In this case report, the authors presented another potential threat to such ablation treatment, which derived from a trachea diverticulum complicated with inflammatory hyperplastic tissue by misdiagnosis as thyroid nodules. The tracheal diverticulum (TD) reported in this study was interpreted as a calcified thyroid nodule on ultrasonography at first, then microwave ablation (MWA) was accordingly recommended as one of the therapeutic options. However, the first author, experienced with the ultrasonic features of PED, insisted the differential diagnosis should be made between nodule and PED. Subsequently, swallow contrast-enhanced ultrasonography (CEUS) and barium meal test were carried out successively, but neither of them reported the presence of PED. Percutaneous fine-needle aspiration (FNA) was hence operated to identify pathological characteristics of the “calcified thyroid nodule”, and cytological tests under microscopy indicated the nodule originated from trachea due to the presence of ciliated columnar epithelial cells with inflammatory exudates within the specimen. Cervical and thoracic X-ray CT examination was further conducted, and a TD was discovered. The case was finally concluded as a TD with inflammatory hyperplastic tissue. The value of this case lies in that once a TD was misdiagnosed as ablation-candidate thyroid nodule in conventional ultrasonography could cause the latent danger to thyroid thermal therapy. Rigorous and effective differential diagnosis prior to thermal ablation procedure could prevent misdiagnosis and mistreatment.

Objective: To evaluate the carotid viscoelasticity using ultrasound shear wave dispersion imaging (USWD) and determine its feasibility.

Methods: Forty-five volunteers were recruited and divided into the group1 (≥50 years old) and group 2 (<50 years old). The shear wave elastic modulus (SWE-A_R and SWE-P_R) and shear wave dispersion indexes (SWD-A_R and SWD-P_R), which located at the anterior and posterior walls of the common carotid artery (CCA), were obtained by USWD, and compared with pulse wave velocity (PWV). Pearson correlation analysis was applied to analyze the related factors of viscoelasticity.

Results: Before and after body mass index, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were adjusted, SWE-A_R, SWE-P_R, SWD-A_R and SWD-P_R were all higher in the group 2 than those of group 1 (all P < 0.05). In all subjects, SWE was negatively correlated with age, SBP, DBP and PWV, respectively (r = -0.282, -0.374, -0.321, -0.256 and all P < 0.05). The SWD was negatively correlated with PWV in the group 1, while positively correlated with SBP in the group 2 (r=-0.393 and r=0.366, all P < 0.05).

Conclusion: The viscoelasticity of arterial wall can be assessed by USWD. It provides a new way to describe arterial disease for clinical study.

The Coronavirus Disease 2019 (COVID-19) has spread rapidly throughout the world. COVID-19 is a highly contagious and potentially lethal infection, and as a result, individuals infected with it are treated in isolation units. Teleultrasound (TUS), particularly with the support of the fifth generation (5G) wireless transmission technology, can provide timely monitoring, fast clinical progress assessment, and help to guide interventional produces for patients with COVID-19 in isolation units. It can also reduce the risk of medical workers infection and save medical resources such as equipment and supplies. The purpose of this paper is to present an overview of operating procedures and ongoing planning with TUS for COVID-19 patients in China.

The current standard technique for diagnosing prostate cancer (PCa) in men at risk relies on a transrectal ultrasound (TRUS)-guided needle biopsy due to its real-time nature and simplicity to obtain systematic histological specimens of the prostate. Also several magnetic resonance imaging (MRI)-based techniques have been employed due to their high detection rate of clinically significant PCa (csPCa). MRI-TRUS fusion imaging contains both the information of MRI and TRUS images for prostate biopsies. This technique combines the strengths of these two techniques, including the superior sensitivity of MRI for targeting cancerous lesions the real time and practicality of TRUS. This review briefly introduces the development of TRUSguided biopsy, MRI-guided biopsy and MRI-TRUS fusion imaging techniques for prostate cancer.

Molecular ultrasound imaging or targeted contrast-enhanced ultrasound (CEUS) is a relatively new technique that has varied applications to augment both diagnostics and therapeutics. Ultrasound contrast agents are conjugated to ligands that bind with specific biomarkers in the areas of interest which can then be quantified using ultrasound technology. This technique has numerous clinical applications including studying pathophysiology of disease, improving diagnostic sensitivity and specificity, and improving localized drug delivery. This technology, most notably, has proven useful in numerous oncologic and cardiovascular applications. Given ultrasound’s advantages over other radiographic studies including its low cost, lack of ionizing radiation, portability, ability to provide real-time imaging, and non-invasiveness, recent investigations have expanded the utility of molecular ultrasound. In this review, we briefly review targeted ultrasound contrast agents and explore the current applications of molecular ultrasound as well as future applications based on the currently published literature.

Objectives: To investigate the clinical value of ultrasound in the diagnosis and treatment of reninoma.
Methods: We retrospectively analyzed the ultrasound findings of 9 patients with reninoma confirmed by pathology after surgical resection in our hospital between September 2012 and August 2019. All patients underwent conventional preoperative ultrasonography. Three underwent contrast-enhanced ultrasound (CEUS) and 3 with complete endogenetic tumor underwent intraoperative ultrasonography.
Results: Of the 9 patients with conventional ultrasound, 7 had renal space-occupying lesions and 2 had missed diagnosis. A hypoechoic or hyperechoic solid mass with regular morphology, clear boundary, capsule, weak echo halo around the mass, incomplete thin strip color blood flow signal around the mass were shown in 7 cases. Color Doppler displayed color flow signal of the incomplete thin strip around the mass and arterial blood supply with an internal thin branch. In 3 patients (including 2 with missing diagnosis by conventional ultrasound) who underwent preoperative contrast-enhanced ultrasound, the reninoma manifested as low enhancement, and the perfusion pattern showed as slow wash-in and slow wash-out compared with normal renal cortex. In 3 patients (including 2 cases of missed diagnosis by conventional ultrasound) with completely endogenic reninoma, intraoperative ultrasound clearly showed the tumor characteristics, and all successfully underwent laparoscopic ultrasound-guided partial nephrectomy.
Conclusions: Preoperative conventional ultrasound combined with CEUS, and clinical features, are helpful for the qualitative diagnosis of reninoma. Laparoscopic partial resection is the first-choice treatment for reninoma. Intraoperative ultrasound can provide real-time imaging, accurately evaluate the tumor status, and provide important information for surgeons.

Hepatic angiomyolipoma (AML) is a rare benign tumor with heterogeneous components composed of vascular, fat, and smooth muscle elements which is often misdiagnosed as other neoplasms such as hepatocellular carcinoma due to nonspecific clinical and image features. A typical case of hepatic AML located in liver with overall clinic and ultrasonography information was analyzed and relative references were reviewed in this article.

Objective: The aims of the current study were to describe the serial CT characteristics of patients infected with COVID-19. In addition, in the light of the CT findings, we tried to determine whether virulence weakens during the transmission with quarantine management.
Methods: Demographics, comorbidity, clinical findings, CT scanning, and scores of the affected lung parenchyma were compared for 131 patients with abnormality on CT images classified as COVID-19 pneumonia and the patients were divided between an imported group (n = 83) and indigenous group (n = 48), according to infected location. Two reviewers scored chest CT examinations for segmental involvement, ground glass opacities, consolidation, and honeycombing opacities. The 55 patients with peak CT "severity score" were selected o make a comparative analysis.
Results: Patients’ demographics and comorbidities and clinical findings did not differ significantly between the two groups. The CT scores distribution trendline of the third CT scanning was lower than the former CT scanning. The peak CT scores trendline of the 55 selected COVID-19 patients in the indigenous group was lower than the imported group. The ROC analysis revealed an area under curve of 0.714 for the CT scanning with an optimal cutoff scores of 2.55 for prediction of contact history, a sensitivity of 76.3%, and a specificity of 52.9%.The peak CT scores of the imported cases were higher than of the indigenous cases and the lung consolidation predominance on CT findings was remarkable in the imported patients (P < 0.05).
Conclusions: CT scanning not only monitored the progression of patients with COVID-19 but also reflected their exposure status to some extent. We suggest that a follow-up CT scanning interval of more than 5 days might be cost effective. The pathogenicity of novel coronavirus may be weakened through transmission under adequate quarantine measures, since indigenous cases have much better progression than imported cases.

Objective: To evaluate the reliability of ultrasonographic (US) elastography of the sternocleidomastoid (SCM) muscle and to define normal strain ratio and shear wave velocity (SWV) values in healthy infants.
Methods: Two hundred healthy infants (mean age ± standard deviation, 1.64±1.78 month; 113 boys and 87 girls) were included in this prospective study. The thickness of bilateral SCM muscles was measured by B-mode ultrasonography, and the stiffness of SCM muscles was measured in both the longitudinal and transverse sections, symmetrical and extensional supine position, by using strain and shear wave elastography. The correlation between thickness and elastic values of the SCM muscle and the following possible influential factors were evaluated: sex, different sides of SCM muscle, different ultrasonic sections and different infant positions.
Results: Both sex and the side of SCM muscle did not show significant correlation with the thickness or stiffness of the SCM muscle (P > 0.05). The stiffness of SCM muscle in the longitudinal section was significantly greater than in the transverse section (P < 0.05). The measurements of the SCM muscle in the stretching position were significantly greater than those in the symmetrical position (P < 0.05).
Conclusion: The stiffness of SCM measured by US elastography is affected by relative positions of the infants. Therefore, the factor should be taken into account when measuring the stiffness of SCM by US elastography. US elastography can evaluate the stiffness of SCM, which is helpful for clinical diagnosis and treatment of children with torticollis.

Objectives: To determine the efficacy of Doppler-based renal resistive index (RRI) in the prediction of acute kidney injury (AKI) in critically ill patients.
Methods: A systematic review and meta-analysis of cohort studies was conducted. Relevant studies were identified in PubMed, Embase and Cochrane Library from inception to November 1, 2020, and reference lists of identified primary studies. Prospective studies that examined the diagnostic accuracy of RRI in AKI were included.
Results: Among the 126 articles identified, 18 were included, with a total of 1656 patients. Bivariate analysis yielded pooled sensitivity and specificity of 0.81 (95% CI 0.74-0.86) and 0.75 (95% CI 0.65-0.83), respectively. The summary positive likelihood ratio was 3.2 (95% CI 2.2-4.6), and negative likelihood ratio was 0.26 (95% CI 0.19-0.36).
Conclusion: Elevated RRI may be an early predictor of AKI in critically ill patients. Further large-scale prospective studies are needed to confirm the predictive efficacy and determine the performance and optimal cutoff value of RRI among the included studies.