Contrast enhanced ultrasound: A review of radiology applications.

Ultrasound contrast agents have been used for decades in Europe and Asia for cardiac and abdominal imaging and are now being more commonly utilized in the United States for radiology applications. Our article reviews the basics of contrast-enhanced ultrasound including how the contrast agent works, advantages and disadvantages, as well as pearls and pitfalls to help the radiologist efficiently integrate this technology into day-to-day clinical practice. We also discuss the diagnosis of focal hepatic lesions as well as off-label applications such as evaluation of renal masses.

Author Correction: Tubular cell and keratinocyte single-cell transcriptomics applied to lupus nephritis reveal type I IFN and fibrosis relevant pathways.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Tubular cell and keratinocyte single-cell transcriptomics applied to lupus nephritis reveal type I IFN and fibrosis relevant pathways.

The molecular and cellular processes that lead to renal damage and to the heterogeneity of lupus nephritis (LN) are not well understood. We applied single-cell RNA sequencing (scRNA-seq) to renal biopsies from patients with LN and evaluated skin biopsies as a potential source of diagnostic and prognostic markers of renal disease. Type I interferon (IFN)-response signatures in tubular cells and keratinocytes distinguished patients with LN from healthy control subjects. Moreover, a high IFN-response signature and fibrotic signature in tubular cells were each associated with failure to respond to treatment. Analysis of tubular cells from patients with proliferative, membranous and mixed LN indicated pathways relevant to inflammation and fibrosis, which offer insight into their histologic differences. In summary, we applied scRNA-seq to LN to deconstruct its heterogeneity and identify novel targets for personalized approaches to therapy.

Design and Validation of a Peer-Teacher-Based Musculoskeletal Ultrasound Curriculum.

RATIONALE AND OBJECTIVES: To design and validate a peer-teacher based musculoskeletal ultrasound curriculum for radiology residents. MATERIALS AND METHODS: A musculoskeletal ultrasound curriculum with hands-on scanning workshops was designed for radiology residents. Prior to the workshops, several residents received 3 hours of hands-on training in ultrasound scanning technique which was overseen by an attending musculoskeletal radiologist; these "peer teachers" then led small-group hands-on scanning during the workshops. Participants performed diagnostic ultrasound examinations at the conclusion of the workshops to assess skill acquisition and 2 months following the workshops to quantify skill retention. Participants also completed surveys to determine confidence in performing musculoskeletal ultrasound examinations. Median scores and interquartile range (25-75%) were calculated, and t test was used to compare results. RESULTS: Thirty seven residents from all years of training and six senior resident or fellow peer teachers participated in four workshops. Diagnostic ultrasound images were obtained in 100% at the conclusion of the workshop and in 79% 2 months later. Prior to the workshops, residents reported low level of musculoskeletal ultrasound knowledge (median 2, interquartile ranges 1-2), and low confidence in performing (1, 1-2) and interpreting (1, 1-2) musculoskeletal ultrasound examinations. There was a significant increase in knowledge (3, 3-4) and confidence performing (3, 3-4) and interpreting (3, 3-4) studies following the workshops (p < 0.001 for all comparisons). CONCLUSION: Hands-on musculoskeletal ultrasound workshops, utilizing a peer teacher led small group format is an effective method of teaching scanning skills to residents. There was excellent skill acquisition, good skill retention, and significant increase in confidence performing and interpreting these studies following completion of the curriculum.

Applications of 3-Dimensional Ultrasonography in the Neck, Excluding the Thyroid.

Ultrasonography (US) of the neck is an accepted, useful imaging modality for many applications beyond its usefulness in thyroid disease. Two-dimensional US has been effectively used for evaluation of many types of neck conditions, and now, 3-dimensional US can be added to the imaging armamentaria. Three-dimensional US is useful in the evaluation of cervical lymph nodes, recurrent/residual thyroid neoplasia, parathyroid glands, parotid and submandibular glands, as well as thyroglossal duct cysts and other assorted palpable and visible abnormalities because of its unique capabilities, including multiplanar reconstruction, accessibility of the coronal view, volume calculation, and regularly spaced incremental slice evaluation.

Sensitivity of 3-Dimensional Sonography in Preoperative Evaluation of Parathyroid Glands in Patients With Primary Hyperparathyroidism.

OBJECTIVES: Preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism facilitates targeted surgery. We assessed the sensitivity of 3-dimensional (3D) sonography for preoperative localization of abnormal parathyroid glands. METHODS: We conducted a retrospective review of patients who underwent parathyroidectomy for primary hyperparathyroidism at a single site at our institution. We compared preoperative 2-dimensional (2D) sonography, 3D sonography, and sestamibi scans with final gland localization at surgery. Two readers reviewed the sonograms to assess inter-reader variability. RESULTS: From January 2010 through April 2015, 52 patients underwent parathyroidectomy after preoperative 2D sonography, 3D sonography, and sestamibi scans. Three-dimensional sonography had sensitivity of 88-92% compared with 69-71% for 2D sonography for gland localization. In patients in whom sonography and sestamibi scans localized abnormalities to the same side, the sensitivities were 100% (43 of 43) for 3D sonography and 96% (48 of 50) for 2D sonography. Three-dimensional sonography had significantly higher sensitivity for localization of glands smaller than 500 mg compared with 2D sonography (88% versus 58%; P = .012). There was better inter-reader agreement between the radiologists when using 3D sonography (κ = 0.65) compared with 2D sonography (κ = 0.41). CONCLUSIONS: We found a significantly higher sensitivity and better inter-reader agreement for 3D sonography compared with 2D sonography for preoperative identification of abnormal parathyroid glands, especially among smaller glands.

New Dimensions in Renal Transplant Sonography: Applications of 3-Dimensional Ultrasound.

BACKGROUND: The aim of this study is to demonstrate the usefulness of adding 3-dimensional (3D) ultrasound in evaluation of renal transplant vasculature compared to 2-dimensional (2D) Duplex ultrasound. METHODS: One hundred thirteen consecutive renal transplant 2D and 3D ultrasound examinations were performed and retrospectively reviewed by 2 board-certified radiologists and a radiology resident individually; each reviewed 2D and then 3D images, including color and spectral Doppler. They recorded ability to visualize the surgical anastomosis and rated visualization on a subjective scale. Interobserver agreement was evaluated. Variant anastomosis anatomy was recorded. Tortuosity or stenosis was evaluated if localized Doppler velocity elevation was present. RESULTS: The reviewers directly visualized the anastomosis more often with 3D ultrasound ((Equation is included in full-text article.)=97.5%) compared with 2D ((Equation is included in full-text article.)=54.5%) [difference in means (DM) = 43% (95% confidence interval (CI) = 36%-50%) (P < 0.001)]. The reviewers visualized the anastomosis more clearly with 3D ultrasound (P < 0.001) [difference in medians = 0.5, 1.0, and 1.0, (95% CI = 0.5-1.0, 0.5-1.0, and 1.0-1.5)]. Detection of variant anatomy improved with 3D ultrasound by 2 reviewers [DM = 7.1% and 8.9% (95% CI = 1%-13% and 4%-14%, respectively) (P < 0.05)]. There was high interobserver agreement [(Equation is included in full-text article.)= 95.3%, (95% CI = 91.9%-98.7%) regarding anastomosis visualization among reviewers with wide-ranging experience. CONCLUSIONS: Direct visualization of the entire anastomosis was improved with 3D ultrasound. Three-dimensional evaluation improved detection of anatomic variants and identified tortuosity as the likely cause of borderline localized elevation in Doppler velocity. The data added by 3D ultrasound may obviate confirmatory testing with magnetic resonance angiography or computed tomographic angiography after equivocal 2D ultrasound results.

Radiology-Pathology Conference: Reviving the Art of Oral Case Presentation in Residency.

RATIONALE AND OBJECTIVES: To improve resident oral case communication and preparatory skills by providing residents an opportunity to prepare for and conduct a new interdisciplinary Radiology-Pathology (Rad-Path) conference series. MATERIALS AND METHODS: To assess whether conference goals were being achieved, we surveyed trainees and attendings in the radiology and pathology departments. Percentages were examined for each variable. Mann-Whitney U test for ordinal variable significance was applied to determine statistical significance between radiology trainee and attending survey responses. RESULTS: Most surveyed radiology trainees (57.1%) strongly agreed or agreed with: "I wish I felt more comfortable with oral presentations." Sixty-five percent of radiology attendings (34 of 52) either agreed or strongly agreed that the residents should be more comfortable with oral case presentations. Of resident Rad-Path conference presenters, 69% (9 of 13) either agreed or strongly agreed that the conference improved their confidence and/or ability to present case information orally. Of responders who attended at least one Rad-Path conference in person, 83% of residents (19/23) and 61% (17/28) of attendings agreed or strongly agreed that the conference improved their ability to formulate a differential diagnosis. Using the Mann-Whitney U test, no significant difference was found between radiology trainees and attendings' responses. CONCLUSIONS: Our Rad-Path correlation conference was specifically designed and structured to provide residents with focused experience in formal oral case preparation and presentation. We consider our conference a success, with 69% of resident presenters reporting that the Rad-Path conference improved their confidence and/or ability to present case information orally.

Survey of current trends in postgraduate musculoskeletal ultrasound education in the United States.

OBJECTIVE: To determine current trends in postgraduate musculoskeletal ultrasound education across various medical specialties in the United States. MATERIALS AND METHODS: A survey regarding musculoskeletal ultrasound education was sent to all program directors for diagnostic radiology and physical medicine rehabilitation residency programs, as well as adult rheumatology and sports medicine fellowship programs in the United States. The survey, sent in July 2015, queried the presence of formal musculoskeletal ultrasound training, the components of such training and case volume for trainees. RESULTS: Response rates were 23, 25, 28 and 33% for physical medicine and rehabilitation, radiology, rheumatology and sports medicine programs, respectively. Among respondents, musculoskeletal ultrasound training was present in 65% of radiology programs, 88% of sports medicine programs, 90% of rheumatology programs, and 100% of physical medicine and rehabilitation programs. Most programs utilized didactic lectures, followed by hands-on scanning. The majority of programs without current training intend to implement such training within 5 years, although radiology programs reported the lowest likelihood of this happening. Most program directors believed that musculoskeletal ultrasound education is important for their trainees, and is of greater importance than it was 10 years ago. Case volume was lowest for radiology trainees and highest for sports medicine trainees. CONCLUSION: Among respondents, the majority of diagnostic radiology programs offer musculoskeletal ultrasound training. However, this experience is even more widespread in other medical specialties, and hands-on training and experience tend to be greater in other specialties than in radiology.

What Is the Appropriate Use of Renal Sonography in an Inner-City Population With New-Onset Acute Kidney Injury?

OBJECTIVES: We aimed to determine the prevalence of hydronephrosis in patients who underwent renal sonography for new-onset acute kidney injury (AKI) and to identify clinical factors predictive of hydronephrosis. In patients with hydronephrosis, we sought to investigate how routine renal sonography affects patient treatment, including performance of interventional procedures. METHODS: A retrospective chart review identified 274 adults with AKI who underwent renal sonography at an urban teaching hospital from January through July 2011. The prevalence of hydronephrosis was determined. Electronic medical records were reviewed for comorbidities, including risk factors for hydronephrosis such as a pelvic mass, prior renal or pelvic surgery, and neurogenic bladder, and for subsequent interventions and outcomes. RESULTS: Sonography showed hydronephrosis in 28 patients (10%); 5 (18%) had subsequent interventions. In a multivariable logistic regression model with the outcome being hydronephrosis, all considered risk factors (pelvic mass, prior renal or pelvic surgery, and neurogenic bladder) were significantly associated with hydronephrosis (odds ratio, 6.4; 95% confidence interval, 2.7-15.4; P < .001) when adjusting for age and diabetes mellitus. Diabetes had a negative predictive value for hydronephrosis. No diabetic patients younger than 85 years and without clinical risk factors had hydronephrosis. CONCLUSIONS: Hydronephrosis is infrequently seen on sonograms in hospitalized patients with AKI who lack risk factors for urinary tract obstruction. Deferral of sonography pending a trial of medical treatment is safe and will reduce medical costs. Adoption of clinical guidelines to assess patients' risk levels for hydronephrosis is critical to avoid unnecessary imaging.

Pearls and pitfalls in first-trimester obstetric sonography.

Ultrasound is the primary imaging modality used in the evaluation of first-trimester vaginal bleeding and pelvic pain. This article will summarize the ultrasound findings in normal first-trimester pregnancy, failed pregnancy, ectopic pregnancy, subchorionic hemorrhage, retained products of conception, and gestational trophoblastic disease. Mastery of the spectrum of sonographic findings in the normal and abnormal first-trimester pregnancy allows the radiologist to make accurate diagnoses and helps to appropriately guide patient management.

Three-dimensional sonography in the evaluation of primary hyperparathyroidism.

Three-dimensional sonography is useful in the preoperative evaluation of patients with primary hyperparathyroidism. In this pictorial essay, we review the characteristic spectrum of grayscale and Doppler appearances of parathyroid glands on 2-dimensional sonography and demonstrate the additional benefits of 3-dimensional scanning.

Multimodality imaging of normal hepatic transplant vasculature and graft vascular complications.

Orthotopic liver transplantation is an important treatment option for patients with end-stage liver disease. Advances in surgical technique, along with improvements in organ preservation and immunosuppression have improved patient outcomes. Post-operative complications, however, can limit this success. Ultrasound is the primary imaging modality for evaluation of hepatic transplants, providing real-time information about vascular flow in the graft. Graft vascular complications are not uncommon, and their prompt recognition is crucial to allow for timely graft salvage. A multimodality approach including CT angiography, MRI, or conventional angiography may be necessary in cases of complex transplant vascular anatomy or when sonography and Doppler are inconclusive to diagnose the etiologies of these complications. The purpose of this article is to familiarize radiologists with the normal post-transplant vascular anatomy and the imaging appearances of the major vascular complications that may occur within the hepatic artery, portal vein, and venous outflow tract, with an emphasis on ultrasound.

Understanding the spectral Doppler waveform of the hepatic veins in health and disease.

Duplex Doppler sonography is a fundamental component of the complete ultrasonographic examination of the liver. Accurate interpretation of the spectral Doppler tracing from the hepatic veins is valuable, as it reflects important cardiac and hepatic physiology. Normally, there are four phases: A, S, V, and D; the S and D waves indicate flow in the antegrade direction toward the heart. In hepatic and cardiac disease, these normal waves may be absent, a finding indicative of flow in a nonphysiologic manner. In addition, transient patient factors such as phase of the respiratory cycle may influence the appearance of the spectral tracing. Familiarity with the normal and abnormal spectral Doppler waveforms from the hepatic veins and knowledge of their respective physiology and pathophysiology provide valuable insights. Systematic analysis of the direction, regularity, and phasicity of the spectral tracing and the ratio of the amplitudes of the S and D waves allows one to arrive at the correct differential diagnosis in most situations.

Gray-scale and color Doppler sonographic features of the vaginal cuff and cervical remnant after hysterectomy.

OBJECTIVE: The purpose of this study was to define the sonographic characteristics of the vaginal cuff and cervical remnant after hysterectomy and to establish normal measurements of each after each type of surgery. MATERIALS AND METHODS: One hundred twenty-one women who had undergone hysterectomy (mean age, 51 years; range, 31-80 years) were studied using transabdominal or transvaginal sonography. Seventy-six patients were acquired retrospectively and 45 prospectively. Hysterectomy types included abdominal, 52% (63/121); supracervical, 17% (20/121); vaginal, 17% (20/121); and unknown, 15% (18/121). Two reviewers, who were blinded to clinical information, evaluated each cuff or remnant in consensus. Transabdominal anteroposterior, transvaginal anteroposterior, and transvaginal length measurements before and after transducer compression, and amount of color Doppler flow as shown by percentage of color pixels (n = 36 patients) were correlated with hysterectomy type and patient age. RESULTS: Supracervical cuffs were larger (p < 0.01) than abdominal and vaginal hysterectomy cuffs (transabdominal sonography anteroposterior, 2.8 vs 1.5 and 1.6 cm; transvaginal sonography anteroposterior, 3.3 vs 1.8 and 1.7 cm; and transvaginal length, 3.0 vs 2.1 and 1.9 cm). Anteroposterior measurements, but not length, decreased significantly with advancing age. Transvaginal length decreased with compression (mean, 0.84 cm; p < 0.0001). Color Doppler flow scores (minimum, 56% [20/36]; mild, 28% [10/36]; moderate, 14% [5/36]; and absent, 3% [1/36]) did not vary with age, time since surgery, or type of surgery. CONCLUSION: The remnant is larger in every dimension after supracervical hysterectomy compared with both abdominal and vaginal hysterectomy and commonly shows some color Doppler flow.

Sonographic comparison of the tubal ring of ectopic pregnancy with the corpus luteum.

OBJECTIVE: Pregnant patients without a sonographically visible intrauterine pregnancy and with a thick-walled cystic adnexal structure present a dilemma. This study compared the utility of various sonographic features in differentiating between the tubal ring of ectopic pregnancy and the corpus luteum. METHODS: Retrospective review of first-trimester transvaginal sonograms revealed a cystic adnexal structure in 79 women. Each structure was evaluated for 6 specific sonographic characteristics: echogenicity of its wall compared with that of the ovary and endometrium, wall thickness in 2 planes, color Doppler flow distribution and percentage of wall circumference, and internal texture. RESULTS: Forty-one (52%) of the 79 women had ectopic pregnancies, and 38 (48%) had corpora lutea. Eleven (32%) of 35 ectopic walls were more echogenic than the endometrium, compared with none of the corpora lutea. A cyst wall less echogenic than the endometrium was more likely in corpora lutea (84% versus 31%; P < .0001). More than twice as many ectopic rinds were more echogenic than ovarian tissue compared with corpora lutea (76% versus 34%; P < .0001). The only predictive internal texture feature was a clear pattern, which was more common in the corpora lutea (P < .01, Fisher exact test). There was no significant difference in mural flow distribution or extent between the 2 groups. CONCLUSIONS: Ancillary sonographic signs to distinguish between an ectopic pregnancy and a corpus luteum include decreased wall echogenicity compared with the endometrium and an anechoic texture, which suggests a corpus luteum.

Aortic coarctation diagnosed in a hypertensive child undergoing Doppler sonography for suspected renal artery stenosis.

A 5-year-old girl presented with hypertension, with no perceived blood pressure differential between the lower and upper extremities. Doppler ultrasound revealed a tardus-parvus pattern with diminished systolic acceleration and peak systolic velocities in the abdominal aorta and both main renal arteries. Doppler interrogation of the suprasternal aorta showed a normal waveform, suggesting a partial obstruction distally. Echocardiography and aortography confirmed severe discrete aortic coarctation with transverse arch hypoplasia. Because classic findings of aortic coarctation may not be present, especially in the older child, the radiologist must be aware that a tardus-parvus Doppler waveform in the abdominal aorta and bilateral renal arteries is suggestive of proximal aortic stenosis, which may be localized by spectral Doppler of the aortic arch.