Contrast -Enhanced Ultrasound: State of the Art in North America

Diagnosis of Pediatric Appendicovesical Fistula by Contrast-enhanced Ultrasound: A Case Report

Appendicovesical fistula is a rare complication associated with appendicitis, Crohn's disease, or appendiceal tumors, posing significant diagnostic challenges. We reported a pediatric case of appendicovesical fistula that remained undiagnosed by non-contrast computed tomography, fluoroscopic voiding cystourethrography (VCUG). Although identified during cystoscopy, its connection to the fistula site could not be determined. However, the transvesical contrast-enhanced ultrasound clearly demonstrated the presence of fistula. Subsequently, laparoscopic appendectomy and bladder repair were performed successfully, leading to complete recovery in the patient. To our knowledge, this is the first reported diagnosis of appendicovesical fistula in children using contrast-enhanced ultrasound.

Contrast-Enhanced Ultrasound of the Chest in Children and Adolescents: A Pilot Study for Assessment of Added Diagnostic Value

OBJECTIVES

To determine the added diagnostic value of contrast-enhanced ultrasound (CEUS) in pediatric chest abnormalities by comparing interpretation of CEUS studies and confidence level to conventional US studies.

METHODS

CEUS studies in patients with a variety of clinically suspected chest abnormalities performed between 2016 and 2020 were reviewed and compared to same-day conventional US studies. Examinations were independently interpreted by 4 radiologists blinded to clinical and other imaging data. Rater confidence was classified as low, moderate, or high. Diagnostic accuracy was determined by comparing image interpretation to patient outcome as the ground truth. Interobserver agreement was also assessed.

RESULTS

Sixteen patients (10 male) with 18 CEUS studies were included. Median rater agreement with ground truth was significantly higher for CEUS (100%) than conventional US (50%; P = .004). Median rater confidence was high (3.0) for CEUS, and low-moderate (1.5) for conventional US (P < .001). CEUS sensitivity (54.6-81.8%) and specificity (63.4-100.0%) were greater than conventional US (45.5-72.7% and 12.5-63.5%, respectively). CEUS false positives (0-4) and false negatives (2-5) were fewer than conventional US (4-7 and 3-6, respectively). Except for one rater pair where agreement was substantial (κ = .78, P < .01), inter-rater agreement for CEUS for all other rater pairs was nonsignificant (κ = .25-0.51, P ≥ .07). Agreement for conventional US was moderate and statistically significant for 3 rater pairs (κ = .55-0.78) and nonsignificant for the remaining 3 rater pairs (P ≥ .06).

CONCLUSIONS

CEUS adds diagnostic value to the assessment of a variety of chest abnormalities. The data support further evaluation of the role of CEUS as a non-invasive, problem-solving technique in children.

The value of quantitative contrast-enhanced ultrasonography analysis in evaluating central retinal artery microcirculation in patients with diabetes mellitus: comparison with colour Doppler imaging

AIM

To compare the efficacy of quantitative contrast-enhanced ultrasonography (CEUS) analysis and colour Doppler ultrasound (CDU) in evaluating central retinal artery (CRA) microcirculation in patients with diabetes mellitus (DM).

MATERIALS AND METHODS

In this prospective study, a total of 55 patients (98 eyes) with DM were enrolled as the study group. They were compared to 46 age-matched healthy volunteers (92 eyes) who were selected as the control group. Each patient underwent CDU and subsequent CEUS examination. CDU and quantitative CEUS parameters were evaluated. The diagnostic efficiency of the diagnostic performance of CEUS and CDU was evaluated and compared, and the scale thresholds of predictive indicators for the diagnosis of proliferative diabetic retinopathy (PDR) were evaluated using receiver operating characteristics (ROC) curve analyses.

RESULTS

Group pairwise comparisons showed that the end diastolic velocity (EDV) and arrival time (AT) of CRA were significant predictors for PDR by CDU and by quantitative CEUS analysis, respectively (all p<0.05). The ROC curve analysis showed that the area under the curve value of AT was significantly higher than that of EDV (0.875 versus 0.634, p=0.0002). Accordingly, an AT cut-off value of 1.07 seconds resulted a sensitivity of 90.62 % and a specificity of 79.31 %.

CONCLUSION

Quantitative CEUS analysis can improve the accuracy of clinical staging of diabetic retinopathy for the patients with DM, and the AT showed the best diagnostic efficiency.

A narrative review on the applications of intracavitary contrast-enhanced ultrasonography in pediatric lower genitourinary anomalies

Purpose

We mainly aimed to perform a narrative review of clinical applications of the three intracavitary contrast-enhanced ultrasonography (CEUS) including contrast-enhanced voiding urosonography (ceVUS), contrast-enhanced retrograde urethrosonography (ceRUG), and contrast-enhanced genitosonography (ceGS) in pediatric lower genitourinary anomalies.

Method

A literature search in the PubMed and Web of Science databases was conducted up to 1 July 2022 on all studies published in English using the search terms "contrast-enhanced voiding urosonography", "contrast-enhanced retrograde urethrosonography", and "contrast-enhanced genitosonography". Trials were limited to pediatric subjects (ages ≤18 years) with no time restrictions. The inclusion criteria were studies on ceVUS, ceRUG, and ceGS to evaluate pediatric lower genitourinary anomalies. Two independent authors summarized the included articles.

Results

Finally, a total of 48 original articles and 6 case reports or case series were included, of which 50 (93%) were only relevant to ceVUS, 3 (5%) articles involved ceGS, while only one (2%) article involved ceRUG, and 87% of the applications of ceVUS were focused on vesicoureteral reflux (VUR). We also searched 24 related reviews, of which 20 involved ceVUS in diagnosing VUR and 4 involved ceRUG and ceGS for other lower genitourinary anomalies.

Conclusion

Intracavitary CEUS including ceVUS, ceRUG, and ceGS in pediatrics has many advantages over other radiological examinations in diagnosing lower genitourinary anomalies. Although ceVUS is widely used in detecting VUR, ceRUG and ceGS have also become promising techniques for evaluating the urethral pathologies and urogenital sinus.

Increasing CEUS utilization in the USA: a call to action for the adult and pediatric body imaging community

Despite its well-established benefits and a powerful body of scientific literature supporting the efficacy of contrast-enhanced ultrasound (CEUS), it has faced challenges in being fully adopted as a diagnostic and problem-solving tool within the USA. This effort, written by experts in performance of and interpretation of CEUS, acts as a roadmap, for those interested in expanding CEUS within their facility. CEUS benefits from a Champion who is knowledgeable and passionate about its performance and who is capable of transferring evidence-based enthusiasm to others. They must be willing to do the legwork required for the successful implementation of a CEUS program, including increasing referrals, expanding applications, and encouraging the inclusion of CEUS into current and established guidelines. The ability of CEUS to resolve a wide range of indeterminate results which come from CT and MR scan represents one of the most compelling arguments for the use of CEUS, decreasing down-stream testing, and reducing time to diagnosis. As utilization grows, the benefits of CEUS will become apparent to other healthcare teams. However, the ultimate beneficiary of improved CEUS utilization will be the patients themselves, who will have greater access to a safe, speedy, cost effective, reliable, and radiation-free diagnostic imaging tool.

Blood Perfusion Characteristics of Renal Cell Carcinoma in the Process of Tumor Growth: Monitored With Multiple Sonographic Modalities

ABSTRACT

Tumor angiogenesis is an essential factor for tumor growth and antiangiogenic therapy. To simulate the blood perfusion characteristics of human renal cell carcinoma (RCC) longitudinally in the process of tumor growth, multimodal ultrasound examination was performed on 40 orthotopic xenograft RCC mouse models. According to tumor maximum diameter ( d ), tumor growth progress was divided into 3 steps: d ≤ 5 mm, 5 mm < d ≤ 10 mm, and d > 10 mm. Color Doppler flow imaging (CDFI), superb microvascular imaging (SMI), and contrast-enhanced ultrasound were administered to monitor tumor perfusion characteristics. The abundance of tumor vascularity on CDFI and SMI was divided into grades 0 to III in ascending order, and their distribution range was categorized into types I to IV. As a result, heterogeneous echogenicity and irregular shape were more common in tumors d > 10 mm than those d < 10 mm ( P < 0.001 for both). Tumor perfusion grade and type on both CDFI and SMI made statistic difference among different growth steps, with higher ratio of hypervascular characteristic in bigger ones (all P < 0.05). Tumor in the same growth step had a higher perfusion grade on SMI than that on CDFI ( P < 0.001). On contrast-enhanced ultrasound, heterogeneous enhancement was more common in those >10 mm ( P < 0.001). It can be concluded that the blood perfusion characteristics of RCC keep on changing during its growth process. In addition, SMI is more sensitive in evaluating tumor perfusion than CDFI.

Microvascular Flow Imaging: A State-of-the-Art Review of Clinical Use and Promise

Vascular imaging with color and power Doppler is a useful tool in the assessment of various disease processes. Assessment of blood flow, from infarction and ischemia to hyperemia, in organs, neoplasms, and vessels, is used in nearly every US investigation. Recent developments in this area are sensitive to small-vessel low velocity flow without use of intravenous contrast agents, known as microvascular flow imaging (MVFI). MVFI is more sensitive in detection of small vessels than color, power, and spectral Doppler, reducing the need for follow-up contrast-enhanced US (CEUS), CT, and MRI, except when arterial and venous wash-in and washout characteristics would be helpful in diagnosis. Varying clinical applications of MVFI are reviewed in adult and pediatric populations, including its technical underpinnings. MVFI shows promise in assessment of several conditions including benign and malignant lesions in the liver and kidney, acute pathologic abnormalities in the gallbladder and testes, and superficial lymph nodes. Future potential of MVFI in different conditions (eg, endovascular repair) is discussed. Finally, clinical cases in which MVFI correlated and potentially obviated additional CEUS, CT, or MRI are shown.

Contrast Enhanced Ultrasound Compared with MRI and CT in the Evaluation of Post-Renal Transplant Complications

Renal transplantation (RT) is the treatment of choice for end-stage renal disease, significantly improving patients’ survival and quality of life. However, approximately 3–23% of patients encounter post-operative complications, and radiology plays a major role for their early detection and treatment or follow-up planning. CT and MRI are excellent imaging modalities to evaluate renal transplant post-operative course; nevertheless, they are both associated with a high cost and low accessibility, as well as some contraindications, making them not feasible for all patients. In particular, gadolinium-based contrast can lead to the rare condition of nephrogenic systemic fibrosis, and iodine-based contrast can lead to contrast-induced nephropathy (CIN). CT also exposes the patients who may require multiple examinations to ionizing radiation. Therefore, considering the overall advantages and disadvantages, contrast-enhanced ultrasound (CEUS) is presently considered an effective first-line imaging modality for post-operative early and long-term follow-up in RT, reducing the need for biopsies and providing adequate guidance for drainage procedures. Hence, this paper aims to review the updated knowledge on CEUS compared with CT and MRI for the evaluation of RT renal transplant complications; advantages, limitations, and possible recommendations are provided.

Diagnosing Pancreatic Adenocarcinoma With Contrast-Enhanced Ultrasonography: A Literature Review of Research in Europe and Asia

The National Cancer Institute names pancreatic cancer the 11^th most common type of cancer in the United States. However, even with a somewhat low prevalence, in 2017, the American Cancer Society reported pancreatic cancer as the fourth leading cause of cancer-related death. With a lack of symptomology and a broad range of risk factors, pancreatic cancer is frequently diagnosed in a later phase than many other types of cancers, thus resulting in higher metastasis along with a poorer prognosis. This highlights the need for early detection and diagnosis. Currently, abdominal ultrasound or contrast-enhanced CT imaging of the abdomen are standard of care. A new technology: contrast-enhanced ultrasound (CEUS), which employs contrast agents to act as acoustic enhancers for ultrasound, has FDA approval for use in hepatic and renal lesions, but not pancreatic. By examining seven individual studies from Europe and Asia, this review aims to examine the diagnostic value of CEUS to initially diagnose pancreatic adenocarcinomas, potentially followed by a biopsy to confirm, when compared against modalities currently used such as conventional ultrasound and CT imaging. CEUS would potentially be more accurate when compared to conventional ultrasound due to the addition of contrast, and when compared against CT and MRI, CEUS would be advantageous in its low cost, similar sensitivities, and specificities, limited renal toxicity, lack of ionizing radiation, short half-life, and its safe use in both adult and pediatric patients. Due to this, additional research is warranted for further FDA approval and future clinical implementation.

Contrast-enhanced ultrasound of blunt abdominal trauma in children

Trauma is the leading cause of morbidity and mortality in children, and rapid identification of organ injury is essential for successful treatment. Contrast-enhanced ultrasound (CEUS) is an appealing alternative to contrast-enhanced CT in the evaluation of children with blunt abdominal trauma, mainly with respect to the potential reduction of population-level exposure to ionizing radiation. This is particularly important in children, who are more vulnerable to the hazards of ionizing radiation than adults. CEUS is useful in hemodynamically stable children with isolated blunt low- to moderate-energy abdominal trauma to rule out solid organ injuries. It can also be used to further evaluate uncertain contrast-enhanced CT findings, as well as in the follow-up of conservatively managed traumatic injuries. CEUS can be used to detect abnormalities that are not apparent by conventional US, including infarcts, pseudoaneurysms and active bleeding. In this article we present the current experience from the use of CEUS for the evaluation of pediatric blunt abdominal trauma, emphasizing the examination technique and interpretation of major abnormalities associated with injuries in the liver, spleen, kidneys, adrenal glands, pancreas and testes. We also discuss the limitations of the technique and offer a review of the major literature on this topic in children, including an extrapolation of experience from adults.