Assessment of Amniotic Fluid Volume in Pregnancy.

Amniotic fluid (AF) is an integral part of the fetal environment and is essential for fetal growth and development. Pathways of AF recirculation include the fetal lungs, swallowing, absorption through the fetal gastrointestinal tract, excretion through fetal urine production, and movement. In addition to being a marker for fetal health, adequate AF is necessary for fetal lung development, growth, and movement. The role of diagnostic imaging is to provide a detailed fetal survey, placental evaluation, and clinical correlation with maternal conditions to help identify causes of AF abnormalities and thereby enable specific therapy. Oligohydramnios prompts evaluation for fetal growth restriction as well as genitourinary issues, including renal agenesis, multicystic dysplastic kidneys, ureteropelvic junction obstruction, and bladder outlet obstruction. Premature preterm rupture of membranes should also be clinically excluded as a cause of oligohydramnios. Clinical trials evaluating amnioinfusion are underway as a potential intervention for renal causes of oligohydramnios. Most cases of polyhydramnios are idiopathic, with maternal diabetes being a common cause. Polyhydramnios prompts evaluation for fetal gastrointestinal obstruction and oropharyngeal or thoracic masses, as well as neurologic or musculoskeletal anomalies. Amnioreduction is performed only for maternal indications such as symptomatic polyhydramnios causing maternal respiratory distress. Polyhydramnios with fetal growth restriction is paradoxical and can occur with maternal diabetes and hypertension. When these maternal conditions are absent, this raises concern for aneuploidy. The authors describe the pathways of AF production and circulation, US and MRI assessment of AF, disease-specific disruption of AF pathways, and an algorithmic approach to AF abnormalities. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Cervical Lymph Node Features Predictive of Suboptimal Adequacy During Ultrasound-Guided Fine-Needle Aspiration in Thyroid Cancer Patients.

PURPOSE: To determine the rate of cytologic and diagnostic adequacy and identify features associated with suboptimal tissue sampling in ultrasound-guided fine-needle aspiration (US-FNA) of suspected nodal disease in thyroid cancer patients. METHODS: A single-institution pathology database was queried for lymph node FNA reports in thyroid cancer patients from 2014 to 2019. Charts were reviewed for demographics, body mass index (BMI), prior thyroidectomy, cancer type, and subsequent surgery. Ultrasound images were retrospectively reviewed for location, size, depth from skin, cystic components, macrocalcification, echogenic foci, and internal vascularity score. Pathology reports were categorized as cellular and diagnostic, hypocellular/acellular but diagnostic with abnormal cells or thyroglobulin levels, or hypocellular and nondiagnostic. Correlation and multivariate regression analyses were performed. RESULTS: Initial query yielded 552 lesions in 343 subjects. Following exclusion, 377 lesions in 255 subjects were included. Mean patient age was 48.5 years (14-90), BMI 28.5, and 66.7% female and 33.3% male. The majority (95.3%) had papillary thyroid carcinoma (PTC); and 65.5% had prior thyroidectomy. 17.7% of lesions were hypocellular/acellular (suboptimal), and 5.6% nondiagnostic. Patient factors had no association (P >.05). Right-sidedness and hypovascularity were associated with hypocellularity (P <.05). Higher long/short-axis ratio and cystic foci were weakly associated. On multivariate analysis, right-sidedness (odds ratio [OR] 1.99; confidence interval [CI] 1.10-3.57) and lower vascularity score (OR 0.54; CI 0.39-0.73) were predictive of suboptimal sampling. CONCLUSION: US-FNA has high diagnostic yield and cellular sample rate. Lesion size had no effect. Right-sidedness and lower vascularity scores were predictive of suboptimal tissue. Identifying these features and expected sample adequacy rates can inform management decisions for thyroid cancer patients with cervical lymphadenopathy.

Transvaginal Ultrasound-Guided Fine-Needle Aspiration Biopsy of Pelvic Lesions.

OBJECTIVES: To assess adequacy of transvaginal ultrasound-guided fine-needle aspiration biopsy (TVUS-FNAB) for pathologic diagnosis of pelvic masses performed using onsite cytopathology consultation. METHODS: In this Institutional Review Board approved, Health Insurance Portability and Accountability Act (HIPAA) compliant study, radiology records were retrospectively queried to identify patients who underwent TVUS-FNAB of a pelvic mass over a 11-year duration. TVUS-FNAB adequacy was determined by correlating cytopathology results with transvaginal ultrasound-guided core-needle biopsy (TVUS-CNB) or surgical pathology results when available, and with clinical diagnostic confidence when additional pathology confirmation was not available. Secondary analysis included patient age, history of hysterectomy, or pelvic malignancy. Target-specific features analyzed included mass size, depth, location, and final pathologic diagnosis. RESULTS: Sixty patients underwent TVUS-FNAB of pelvic masses, 43 of which underwent FNAB only and 17 underwent both TVUS-FNAB and TVUS-CNB during the same procedure. TVUS-FNAB alone was adequate for diagnosis in 51 (85%) cases and addition of core-needle biopsy (CNB) achieved a diagnosis in additional 4 patients, increasing overall diagnostic accuracy to 92% (55/60). FNAB inadequacy had statistically significant association with increasing mass depth, occurrence of a minor intraprocedural complication, and decision to perform a CNB (P <.05). Number of FNAB passes, mass size, history of hysterectomy, and final diagnosis were not statistically significant predictors of FNAB adequacy. CONCLUSION: TVUS-FNAB has a high specimen adequacy rate when performed with an onsite cytopathologist and can be considered first-line approach for image-guided sampling of pelvic lesions with option to add CNB if preliminary cytopathologic review does not confirm sample adequacy.

US-guided Interventions to Diagnose and Treat Gynecologic and First-Trimester Disease.

US-guided procedures have an essential role in the diagnosis and treatment of multiple obstetric and gynecologic conditions, can be performed with either transvaginal or transabdominal approaches, and include biopsy of masses, aspiration of fluid collections, injection of therapeutic materials, and saline-infused sonohysterography and hysterosalpingo contrast-enhanced sonography. The full digital presentation is available online. ©RSNA, 2021.

O-RADS for Ultrasound: A User's Guide, From the AJR Special Series on Radiology Reporting and Data Systems.

The Ovarian-Adnexal Reporting and Data System (O-RADS) is a lexicon and risk stratification tool designed for the accurate characterization of adnexal lesions and is essential for optimal patient management. O-RADS is a recent addition to the American College of Radiology (ACR) reporting and data systems and consists of ultrasound (US) and MRI arms. Since most ovarian or adnexal lesions are first detected with US, O-RADS US is considered the primary assessment tool. Application of O-RADS US is recommended whenever a nonphysiologic lesion is encountered. Lesion characterization may be streamlined by use of an algorithmic approach focused on relevant features and an abbreviated version of the lexicon. Resources to expedite O-RADS US categorization and determination of a management recommendation include easy online access to the ACR color-coded risk stratification scorecards and an O-RADS US calculator that is available as a smartphone app. Reporting should be concise and include relevant features for risk stratification that adhere to lexicon terminology. Technical considerations include optimization of gray-scale and color Doppler technique and performance of problem-solving maneuvers to help avoid common pitfalls. This review provides a user-friendly summary of O-RADS US with practical tips for everyday clinical use.

Ultrasound Liver Imaging Reporting and Data System (US LI-RADS): An Overview with Technical and Practical Applications.

The Ultrasound Liver Imaging Reporting and Data System (US LI-RADS), introduced in 2017 by the American College of Radiology, standardizes the technique, interpretation, and reporting of screening and surveillance ultrasounds intended to detect hepatocellular carcinoma in high-risk patients. These include patients with cirrhosis of any cause as well as subsets of patients with chronic hepatitis B viral infection. The US LI-RADS scheme is composed of an ultrasound category and a visualization score: ultrasound categories define the exam as negative, subthreshold, or positive and direct next steps in management; visualization scores denote the expected sensitivity of the exam, based on adequacy of liver visualization with ultrasound. Since its introduction, multiple institutions across the United States have implemented US LI-RADS. This review includes a background of hepatocellular carcinoma and US LI-RADS, definition of screening/surveillance population, recommendations and tips for technique, interpretation, and reporting, and preliminary outcomes analysis.

Problem Solved: Integral Applications of Musculoskeletal Ultrasound.

Musculoskeletal ultrasound has grown substantially in use over the past several years as an indispensable companion to magnetic resonance imaging and other imaging modalities. This article reviews 10 integral applications of musculoskeletal ultrasound as a problem-solving tool with correlative case examples. These applications include the following: (1) accessibility and portability, (2) targeted imaging, (3) dynamic imaging, (4) contralateral comparison, (5) Doppler imaging, (6) increased spatial resolution, (7) solid versus cystic comparison, (8) posttraumatic imaging, (9) postsurgical imaging, and (10) treatment delivery and optimization. The review will help the radiologist recognize the complementary uses of musculoskeletal ultrasound with radiography, computed tomography, and magnetic resonance imaging.

US Evaluation of Twin Pregnancies: Importance of Chorionicity and Amnionicity.

The twin birth rate is increasing in the United States. Twin pregnancies can be dichorionic or monochorionic (MC). MC twins account for 20% of twin pregnancies but 30% of all-cause pregnancy-related complications. This article describes the imaging findings that establish chorionicity and amnionicity. Ideally, these are established in the first trimester when accuracy is high, but they can also be determined later in pregnancy. Complications unique to MC twin pregnancy include twin-twin transfusion syndrome, twin anemia polycythemia sequence, twin reversed arterial perfusion sequence, and selective fetal growth restriction. The US features, staging systems, and management of these complications are reviewed, and the consequences of MC twin demise are illustrated. Ongoing surveillance for these conditions starts at 16 weeks gestation. Monoamniotic (MA) twins are a small subset of MC twins. In addition to all of the MC complications, specific MA complications include cord entanglement and conjoined twinning. Radiologists must be able to determine chorionicity and amnionicity and should be aware of potential complications so that patients may be referred to appropriate regional specialized centers. A proposed algorithm for referral to specialized fetal treatment centers is outlined. Online supplemental material is available for this article. ©RSNA, 2019.

Role of US LI-RADS in the LI-RADS Algorithm.

The US Liver Imaging Reporting and Data System (LI-RADS) was released in 2017 and is the newest of the four American College of Radiology (ACR) LI-RADS algorithms. US LI-RADS provides standardized terminology, technical recommendations, and a reporting framework for US examinations performed for screening or surveillance in patients at risk for developing hepatocellular carcinoma (HCC). The appropriate patient population for screening and surveillance includes individuals who are at risk for developing HCC but do not have known or suspected cancer. This includes patients with cirrhosis from any cause and subsets of patients with chronic hepatitis B virus infection in the absence of cirrhosis. In an HCC screening or surveillance study, US LI-RADS recommends assigning two scores that apply to the entire study: the US category, which determines follow-up, and a visualization score, which communicates the expected level of sensitivity of the examination but does not affect management. Three US categories are possible: US-1 negative, a study with no evidence of HCC; US-2 subthreshold, a study in which an observation less than 10 mm is depicted that is not definitely benign; and US-3 positive, a study in which an observation greater than or equal to 10 mm or a new thrombus in vein is identified, for which diagnostic contrast material-enhanced imaging is recommended. Three visualization scores are possible: A (no or minimal limitations), B (moderate limitations), and C (severe limitations). ©RSNA, 2019.

Placenta accreta spectrum: value of placental bulge as a sign of myometrial invasion on MR imaging.

PURPOSE: To evaluate correlation of "placental bulge sign" with myometrial invasion in placenta accreta spectrum (PAS) disorders. Placental bulge is defined as deviation of external uterine contour from expected plane caused by abnormal outward bulge of placental tissue. MATERIALS AND METHODS: In this IRB-approved, retrospective study, all patients undergoing MRI for PAS disorders between March 2014 and 2018 were included. Patients who delivered elsewhere were excluded. Imaging was reviewed by 2 independent readers. Surgical pathology from Cesarean hysterectomy or pathology of the delivered placenta was used as reference standard. Fisher's exact and kappa tests were used for statistical analysis. RESULTS: Sixty-one patients underwent MRI for PAS disorders. Two excluded patients delivered elsewhere. Placental bulge was present in 32 of 34 cases with myometrial invasion [True positive 32/34 = 94% (95% CI 0.80-0.99)]. Placental bulge was absent in 24 of 25 cases of normal placenta or placenta accreta without myometrial invasion [True negative = 24/25, 96% (95% CI 80-99.8%)]. Positive and negative predictive values were 97% and 96%, respectively. Placental bulge in conjunction with other findings of PAS disorder was 100% indicative of myometrial invasion (p < 0.01). Kappa value of 0.87 signified excellent inter-reader concordance. In 1 false positive, placenta itself was normal but the bulge was present. Surgical pathology revealed markedly thinned, fibrotic myometrium without accreta. One false-negative case was imaged at 16 weeks and may have been imaged too early. CONCLUSIONS: Placental bulge in conjunction with other findings of invasive placenta is 100% predictive of myometrial invasion. Using the bulge alone without other signs can lead to false-positive results.

Advanced ultrasound applications in the assessment of renal transplants: contrast-enhanced ultrasound, elastography, and B-flow.

Ultrasound is routinely used as the first imaging exam for evaluation of renal transplants and can identify most major surgical complications and evaluate vascularity with color Doppler. Ultrasound is limited, however, in the detection of parenchymal disease processes and Doppler evaluation is also prone to technical errors. Multiple new ultrasound applications have been developed and are under ongoing investigation which could add additional diagnostic capability to the routine ultrasound exam with minimal additional time, cost, and patient risk. Contrast-enhanced ultrasound (CEUS) can be used off-label in the transplant kidney, and can assist in detection of infection, trauma, and vascular complications. CEUS also can demonstrate perfusion of the transplant assessed quantitatively with generation of time-intensity curves. Future directions of CEUS include monitoring treatment response and microbubble targeted medication delivery. Elastography is an ultrasound application that can detect changes in tissue elasticity, which is useful to diagnose diffuse parenchymal disease, such as fibrosis, otherwise unrecognizable with ultrasound. Elastography has been successfully applied in other organs including the liver, thyroid, and breast; however, it is still under development for use in the transplant kidney. Unique properties of the transplant kidney including its heterogeneity, anatomic location, and other technical factors present challenges in the development of reference standard measurements. Lastly, B-flow imaging is a flow application derived from B-mode. This application can show the true lumen size of a vessel which is useful to depict vascular anatomy and bypasses some of the pitfalls of color Doppler such as demonstration of slow flow.

US LI-RADS: ultrasound liver imaging reporting and data system for screening and surveillance of hepatocellular carcinoma.

Ultrasound is the most widely used imaging tool for hepatocellular carcinoma (HCC) screening and surveillance. Until now, this method has lacked standardized guidelines for interpretation, reporting, and management recommendations [1-5]. To address this need, the American College of Radiology (ACR) has developed the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) algorithm. The proposed algorithm has two components: detection scores and visualization scores. The detection score guides management and has three categories: US-1 Negative, US-2 Subthreshold, and US-3 Positive. The visualization score informs the expected sensitivity of the ultrasound examination and also has three categories: Visualization A: No or minimal limitations; Visualization B: Moderate limitations; and Visualization C: Severe limitations. Standardization in ultrasound utilization, reporting, and management in high-risk individuals has the capacity to improve communication with patients and referring physicians, unify screening and surveillance algorithms, impact outcomes, and supply quantitative data for future research.

Evidence Supporting LI-RADS Major Features for CT- and MR Imaging-based Diagnosis of Hepatocellular Carcinoma: A Systematic Review.

The Liver Imaging Reporting and Data System (LI-RADS) standardizes the interpretation, reporting, and data collection for imaging examinations in patients at risk for hepatocellular carcinoma (HCC). It assigns category codes reflecting relative probability of HCC to imaging-detected liver observations based on major and ancillary imaging features. LI-RADS also includes imaging features suggesting malignancy other than HCC. Supported and endorsed by the American College of Radiology (ACR), the system has been developed by a committee of radiologists, hepatologists, pathologists, surgeons, lexicon experts, and ACR staff, with input from the American Association for the Study of Liver Diseases and the Organ Procurement Transplantation Network/United Network for Organ Sharing. Development of LI-RADS has been based on literature review, expert opinion, rounds of testing and iteration, and feedback from users. This article summarizes and assesses the quality of evidence supporting each LI-RADS major feature for diagnosis of HCC, as well as of the LI-RADS imaging features suggesting malignancy other than HCC. Based on the evidence, recommendations are provided for or against their continued inclusion in LI-RADS. © RSNA, 2017 Online supplemental material is available for this article.

Distal Forearm Fracture Open Reduction-Internal Fixation: Sonographic Detection of Hardware Malalignment and Associated Tendon Injuries Missed by Radiography.

Tendon injury is a known complication of distal radius fracture plate and screw fixation. Targeted musculoskeletal sonography is uniquely capable of assessing both tendon integrity and hardware abnormalities not recognized on radiographs. Each of the 3 patients described presented with pain after an open reduction-internal fixation following a distal forearm fracture. In each patient, radiographic findings, specifically the hardware position, were interpreted as normal. Important radiographically occult observations were subsequently made with sonography, including 3 proud screws and tendon injuries, all of which required surgical treatment. This case series demonstrates the clinical utility of musculoskeletal sonography in symptomatic patients after distal radius open reduction-internal fixation with negative radiographic findings. In our practice, sonography has been the most useful modality for precluding missing or delaying the diagnosis and treatment of these hardware complications. We advocate its use as an adjunct in any department performing musculoskeletal imaging.

Fetal stomach and gallbladder in contact with the bladder wall is a common ultrasound sign of stomach-down left congenital diaphragmatic hernia.

PURPOSE: The aim of this study was to identify sonographic (US) findings that can assist in prenatal diagnosis of stomach-down left congenital diaphragmatic hernia (CDH), specifically related to positioning of the abdominal contents including the stomach, bladder, and gallbladder. METHODS: All US examinations with a postnatally confirmed diagnosis of stomach-down left CDH over a 13-year period were retrospectively reviewed for abnormal position of the abdominal contents, including whether the fetal stomach was in contact with the urinary bladder. Normal fetuses that underwent comprehensive US surveys were similarly evaluated for comparison in a 2:1 ratio. RESULTS: Twenty-two fetuses with stomach-down left CDH were identified in a cohort of 278 fetuses with left CDH. In 15/22 (68.2%) cases of stomach-down left CDH, the bladder and stomach walls were in contact. Contact of the fetal gallbladder with the fetal bladder wall was also observed and was present even more commonly (17/22 cases [77.3%]). There was no case of either the stomach or gallbladder in contact with the bladder wall in the normal fetal cohort (n = 44). CONCLUSIONS: Recognition of the fetal stomach and/or gallbladder in contact with the bladder wall can help in the detection of stomach-down left CDH. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:8-13, 2017.

Transvaginal Ultrasound-Guided Biopsy of Deep Pelvic Masses: How We Do It.

The purpose of this review is to discuss the rationale and indications for transvaginal ultrasound-guided biopsy. Transvaginal ultrasound-guided biopsy can be a helpful tool for diagnosis and treatment planning in the evaluation of pelvic masses, particularly when the anatomy precludes a transabdominal or posterior transgluteal percutaneous biopsy approach. A step-by-step summary of the technique with preprocedure and postprocedure considerations is included.

A Benign Anomalous Umbilical Vein: Not All Umbilical Veins That Wander Are Lost.

A rare case of an anomalous umbilical vein with a previously unreported outcome is described. Most reported cases of anomalous umbilical veins are associated with significant concurrent fetal anomalies and poor outcomes. Fetal magnetic resonance imaging was used in this case to confirm normal portal and hepatic venous vasculature. No other fetal anomalies were identified on ultrasound. The infant was delivered at term and is healthy at the age of 8 months. Parental anxiety regarding the diagnosis was the only adverse consequence of this incidental finding.

US Findings in Patients at Risk for Pancreas Transplant Failure.

Purpose To determine if ultrasonographic (US) findings, including Doppler US findings, are associated with subsequent pancreas transplant failure. Materials and Methods A cohort of adult patients who underwent pancreas transplantation at a tertiary institution over the course of 10 years (from 2003 to 2012) was retrospectively evaluated for failure, which was defined as return to insulin therapy or surgical graft removal. The institutional review board provided a waiver of informed consent. All US images obtained within the 1st postoperative year were reviewed for three findings: arterial flow (presence or absence of intraparenchymal forward diastole flow), splenic vein thrombus, and edema. These findings were correlated with pancreas graft failure within 1-year after surgery by using Cox proportional hazards models and hazard ratios. Results A total of 228 transplants were included (mean patient age, 41.6 years; range, 19-57 years; 122 men, 106 women). Absent or reversed arterial diastolic flow was identified in nine of 20 failed transplants (sensitivity, 45%; 95% confidence interval [CI]: 23, 68) and in 15 of 208 transplants that survived (specificity, 93% [193 of 208]; 95% CI: 89, 96). The Cox proportional hazard ratio was 6.2 (95% CI: 3.1, 12.4). Splenic vein thrombus was identified in 10 of 20 failed transplants (sensitivity, 50%; 95% CI: 27, 73) and in 25 of 208 transplants that survived (specificity, 88% [183 of 208]; 95% CI: 83, 92). The Cox proportional hazard ratio was 4.2 (95% CI: 2.4, 7.4). Edema had the lowest specificity (Cox proportional hazard ratio, 2.0; 95% CI: 1.3, 2.9). In the multivariate analysis, only absent or reversed arterial diastolic flow remained significantly associated with transplant failure (adjusted hazard ratio, 3.6; 95% CI: 1.0, 12.8; P = .045). Conclusion Absent or reversed diastolic arterial Doppler flow has a stronger association with transplant failure than does splenic vein thrombus or edema. (©) RSNA, 2016.

In Utero Diagnosis of Unilateral Bronchial Atresia: One Pathologically Proven and 2 Presumed Cases With Similar Sonographic Findings at Presentation.

Unilateral bronchial atresia is a rare prenatal diagnosis that can be confused with other congenital lung abnormalities, particularly congenital pulmonary airway malformation. Accurate distinction between these entities is important for appropriate clinical care and prognosis. Familiarity of the key imaging and clinical features of unilateral bronchial atresia in comparison to other fetal lung abnormalities should increase the likelihood of achieving a timely and accurate diagnosis.