Contrast Enhanced Ultrasound in Pediatric Patients: A Real Challenge

Testicular torsion diagnosis and injury assessment using photoacoustic oxygenation imaging

Testicular torsion (TT) is a medical emergency that requires immediate diagnostic evaluation. Photoacoustic imaging (PAI) has the potential to provide spatially resolved oxygen saturation (sO₂), which can serve as a valuable marker in TT diagnosis. We investigated the potential of PAI as an alternative method for TT diagnosis and testicular injury assessment. We measured sO₂ levels in different degrees of TT models using PAI at various time points. Based on histopathological results, we found that the averaged sO₂ per pixel (sO2®) and reduction of sO2® (rsO₂) in twisted testicles had significant correlations with hypoxic conditions. Both sO2® and rsO₂ exhibited excellent diagnostic abilities in detecting TT and identifying ischemia/hypoxia injury following TT. Furthermore, PAI-measured sO₂ demonstrated favorable diagnostic capabilities in discriminating if the testicle had suffered irreversible injury. In summary, PAI presents a potentially promising novel approach in evaluating TT and warrants further clinical investigation.

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.

Differentiating malignant and benign focal liver lesions in children using CEUS LI-RADS combined with serum alpha-fetoprotein

BACKGROUND

Contrast-enhanced ultrasound (CEUS) can be used to diagnose focal liver lesions (FLLs) in children. The America College of Radiology developed the CEUS liver imaging reporting and data system (LI-RADS) for standardizing CEUS diagnosis of FLLs in adult patients. Until now, no similar consensus or guidelines have existed for pediatric patients to improve imaging interpretation as adults.

AIM

To evaluate the performance of CEUS LI-RADS combined with alpha-fetoprotein (AFP) in differentiating benign and malignant FLLs in pediatric patients.

METHODS

Between January 2011 and January 2021, patients ≤ 18 years old who underwent CEUS for FLLs were retrospectively evaluated. The following criteria for diagnosing malignancy were proposed: Criterion I considered LR-4, LR-5, or LR-M lesions as malignancies; criterion II regarded LR-4, LR-5 or LR-M lesions with simultaneously elevated AFP (≥ 20 ng/mL) as malignancies; criterion III took LR-4 Lesions with elevated AFP or LR-5 or LR-M lesions as malignancies. The sensitivity, specificity, accuracy and area under the receiver operating characteristic curve (AUC) were calculated to determine the diagnostic value of the aforementioned criteria.

RESULTS

The study included 63 nodules in 60 patients (mean age, 11.0 ± 5.2 years; 26 male). There were no statistically significant differences between the specificity, accuracy, or AUC of criterion II and criterion III (95.1% vs 80.5%, 84.1% vs 87.3%, and 0.794 vs 0.902; all P > 0.017). Notably, criterion III showed a higher diagnostic sensitivity than criterion II (100% vs 63.6%; P < 0.017). However, both the specificity and accuracy of criterion I was inferior to those of criterion II and criterion III (all P < 0.017). For pediatric patients more than 5 years old, the performance of the three criteria was overall similar when patients were subcategorized by age when compared to all patients in aggregate.

CONCLUSION

CEUS LI-RADS combined with AFP may be a powerful diagnostic tool in pediatric patients. LR-4 with elevated AFP, LR-5 or LR-M lesions is highly suggestive of malignant tumors.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB): An Update on the Pediatric CEUS Registry on Behalf of the "EFSUMB Pediatric CEUS Registry Working Group"

The European Federation of Ultrasound in Medicine and Biology (EFSUMB) created the "EFSUMB Pediatric Registry" (EFSUMB EPR) with the purpose of collecting data regarding the intravenous application of pediatric contrast-enhanced ultrasound (CEUS). The primary aim was to document the current clinical practice and usefulness of the technique and secondarily to assess CEUS safety in children. We issue the preliminary results of this database and examine the overall practice of CEUS in children in Europe.

Contrast-Enhanced Ultrasound (CEUS) in Non-Traumatic Abdominal Emergencies

Conventional ultrasound imaging (US) is the first-line investigation in acute non-traumatic abdominal emergencies, but sometimes it needs further examinations, such as computed tomography (CT), to reach a certain diagnosis. Contrast-enhanced ultrasound (CEUS), through injection of contrast medium, may provide the radiologist with additional information that could not be investigated with baseline US. It could help reach a diagnosis and rapidly determine the proper therapy in an emergency setting. The purpose of this review is to explain and illustrate the various possibilities and limitations of CEUS in acute non-traumatic abdominal diseases, in particular acute inflammation, parenchymal infarcts, and hemorrhages.

Additional value of superb microvascular imaging for assessing hepatic arterial blood flow after pediatric liver transplantation

BACKGROUND

The aim of this study was to explore the value of SMI compared with conventional ultrasonography for assessing hepatic arterial blood flow after pediatric liver transplantation.

METHODS

From March 2018 to November 2018, a total of 105 pediatric recipients with biliary atresia underwent liver transplantation in our hospital. Ultrasound examinations were performed at the bedside in the intensive care unit to check the patency of the blood flow in the hepatic allograft. CDI, PDI, cSMI, and mSMI were performed to assess the display, orientation, and distribution of the graft hepatic artery. Ultrasound examinations were performed by one radiologist, and the images were judged by two observers.

RESULTS

The median age, weight, and height of the recipients were 6.97 (5.92, 9.58) months, 6.50 (6.00, 7.80) kg, and 64.00 (62.00, 68.00) cm, respectively. The measure of kappa agreement was 0.902, 0.889, 0.882, and 0.882 for CDI, PDI, cSMI, and mSMI, respectively. HAT occurred in 7 pediatric recipients and was confirmed by CTA (computed tomography angiography) and surgery. The diagnostic performance of sensitivity, specificity, PPV (positive predictive value), NPV (negative predictive value), and accuracy were 100%, 92.86%, 50%, 100%, and 93.33% for CDI and 100%, 98.98%, 87.50%, 100%, and 99.05% for SMI.

CONCLUSIONS

As an additional method to CDI, SMI can clearly show the distribution of hepatic arterial blood flow and provide more details, thereby markedly improving the diagnostic performance of postoperative HAT.

Intracavitary contrast-enhanced ultrasonography in children: review with procedural recommendations and clinical applications from the European Society of Paediatric Radiology abdominal imaging task force

Contrast-enhanced ultrasonography (US) has become an important supplementary tool in many clinical applications in children. Contrast-enhanced voiding urosonography and intravenous US contrast agents have proved useful in routine clinical practice. Other applications of intracavitary contrast-enhanced US, particularly in children, have not been widely investigated but could serve as a practical and radiation-free problem-solver in several clinical settings. Intracavitary contrast-enhanced US is a real-time imaging modality similar to fluoroscopy with iodinated contrast agent. The US contrast agent solution is administered into physiological or non-physiological body cavities. There is no definitive list of established indications for intracavitary US contrast agent application. However, intracavitary contrast-enhanced US can be used for many clinical applications. It offers excellent real-time spatial resolution and allows for a more accurate delineation of the cavity anatomy, including the internal architecture of complex collections and possible communications within the cavity or with the surrounding structures through fistulous tracts. It can provide valuable information related to the insertion of catheters and tubes, and identify related complications such as confirming the position and patency of a catheter and identifying causes for drainage dysfunction or leakage. Patency of the ureter and biliary ducts can be evaluated, too. US contrast agent solution can be administered orally or a via nasogastric tube, or as an enema to evaluate the gastrointestinal tract. In this review we present potential clinical applications and procedural and dose recommendations regarding intracavitary contrast-enhanced ultrasonography.

A rare case of accessory spleen torsion in a child diagnosed by ultrasound (US) and contrast-enhanced ultrasound (CEUS)

INTRODUCTION

Accessory spleen, also known as supernumerary spleen or splenunculum, is a congenital anomaly of the spleen due to a fusion defect during the embryogenesis. Usually it is detected casually during an ultrasound (US) examination of the abdomen and it is asymptomatic.

CASE REPORT

RESULTS: We present a case of a 12 years old male patient, with 2-days history of left abdominal pain, without fever, gastrointestinal or genitourinary symptoms. The day before our observation, the patient had gone to another hospital, from where he had been discharged with medical analgesic therapy, without any benefit. Blood tests were normal, the Ultrasound abdominal examination showed normal aspect of abdominal organs, but the presence in the left side of a small round parenchymal structure surrounded by hyperechogenic mesenteric fat. We interpreted this image as an accessory spleen, complicated by torsion. As the torsion of accessory spleen is a quite rare occurrence, we carried out a contrast enhanced ultrasound (CEUS) to get more information. CEUS showed the absence of enhancement of the nodular formation, suggestive for a complete lack of vascularization; the spleen was normally enhanced. While the management in case of accessory spleen torsion is non-operative, in this case the patient underwent surgical exploration, due to the persistence of abdominal pain despite the medical therapy, with clinical signs of peritoneal reaction, mimicking an acute abdomen. Surgery confirmed the diagnosis of accessory spleen torsion.

DISCUSSION AND CONCLUSIONS

In conclusion, US is the first diagnostic tool in pediatric abdominal pain and allows to direct the diagnosis; the use of CEUS helps to clarify the US reports, without leaving doubts about the parenchymal vascularization of the abdominal organ involved.

Contrast enhanced ultrasound (CEUS) imaging of solid benign focal liver lesions

Ultrasound is well accepted worldwide for imaging of the liver. Absences of radiation exposure, low cost and large diffusion are some of the advantages that make this technique the first to be used in the assessment of focal liver lesions (FLL). Areas covered: Contrast enhanced ultrasound (CEUS) has been introduced more than twenty years ago, and its detection rate is comparable to that of contrast enhanced magnetic resonance imaging (CEMRI) and contrast enhanced computed tomography (CECT). In this narrative review, we discuss the main CEUS features of benign liver lesions and controversies in published results including the gold standard chosen and the quality and knowledge of the preferred techniques. Expert commentary: CEUS is safe and allows an immediate evaluation of the nature of FLL. CEUS permits differentiation between malignant and benign FLL in healthy liver parenchyma by analysing the arterial, portal venous and late phases. CEMRI and CECT are reliable to characterize FLL but higher costs, radiation exposure, nephrotoxicity (in particular for CECT) and absence of real time imaging limit the appropriate evaluation of FLL. Therefore CEUS can be preferred in most clinical situations, and when results are unclear or suggestive for malignant FLL, biopsy and histological examination can be directly initiated avoiding unnecessary additional imaging.

Novel ultrasound-based methods to assess liver disease: The game has just begun

In the last 10 years the availability of ultrasound elastography allowed to diagnose and stage liver fibrosis in a non-invasive way and changed the clinical practice of hepatology. Newer ultrasound-based techniques to evaluate properties of the liver tissue other than fibrosis are emerging and will lead to a more complete characterization of the full spectrum of diffuse and focal liver disease. Since these methods are currently undergoing validation and go beyond elastography for liver tissue evaluation, they were not included in the recent guidelines regarding elastography issued by the European Federation of Societies in Ultrasound in Medicine and Biology. In this review paper, we outline the major advances in the field of ultrasound for liver applications, with special emphasis on techniques that could soon be part of the future armamentarium of ultrasound specialists devoted to the assessment of liver disease. Specifically, we discuss current and future ultrasound assessment of steatosis, spleen stiffness for portal hypertension, and elastography for the evaluation of focal liver lesions; we also provide a short glimpse into the next generation of ultrasound diagnostic methods.

How to perform Contrast-Enhanced Ultrasound (CEUS)

"How to perform contrast-enhanced ultrasound (CEUS)" provides general advice on the use of ultrasound contrast agents (UCAs) for clinical decision-making and reviews technical parameters for optimal CEUS performance. CEUS techniques vary between centers, therefore, experts from EFSUMB, WFUMB and from the CEUS LI-RADS working group created a discussion forum to standardize the CEUS examination technique according to published evidence and best personal experience. The goal is to standardise the use and administration of UCAs to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.

Contrast-enhanced ultrasound using sulfur hexafluoride is safe in the pediatric setting

Background

Contrast-enhanced ultrasound (CEUS) by using sulfur hexafluoride microbubbles is not licensed for use in children, but its off-label use is widespread.

Purpose

To outline our experience with the off-label use of CEUS in children, specifically with regards to safety.

Material and Methods

We retrieved all records of 10681 patients aged under 18 years who underwent abdominal ultrasound (US) January 2004 to December 2014. We then identified those who underwent an abdominal CEUS using sulfur hexafluoride microbubbles. Electronic patient charts were used to verify the indication for contrast agent, dose, possible adverse effects as well as information on patient height, weight, and age.

Results

We identified 173 patients (mean age, 11 years; range, 0.1–18 years) who underwent a total of 287 CEUS exams. Of all exams, 46% were performed on the native liver, 31% on a transplanted liver, and 23% on other organs. The indications were “circulatory status?” (40%), “characterization of lesion?” (40%), and miscellaneous (20%). Mean contrast dose was 2.3 mL (range, 0.1–8.1 mL). No immediate adverse effects were recorded. One patient experienced itching the day after, but this was considered to be a reaction to concomitantly administered fentanyl.

Conclusion

The use of intravenous ultrasound contrast seems safe in patients aged under 18 years and our results do not support the current practice to restrict the use of CEUS in children.

Role of contrast-enhanced endoscopic ultrasound in lymph nodes

Diagnosing unclear lymph node (LN) enlargements in the mediastinum and abdomen is the most important indication of endoscopic ultrasound (EUS)-fine needle aspiration (FNA) after the diagnosis and treatment of pancreatic diseases. Investigating LNs in these areas can happen in different clinical settings. Mostly, it is the first modality in general LN diseases without any peripheral LN enlargements. On the other hand, it can be the question of LN involvement in a known or suspected primary tumor. Due to EUS-FNA cytology, those questions can be answered highly, accurately. However, a primary discrimination of LNs might be helpful to increase the diagnostic value of the FNA cytology, especially in cases with multiple LN enlargements and hard to reach enlarged LNs for example by vessel interposition. Because of the unreliability of B-mode criteria, further diagnostic improvements such as elastography and contrast-enhanced EUS are investigated to increase the accuracy of the initial diagnosis.

Dynamic contrast-enhanced ultrasound of the bowel wall with quantitative assessment of Crohn's disease activity in childhood

Background

Contrast-enhanced ultrasound (CEUS) has become an established non-invasive, patient-friendly imaging technique which improves the characterization of lesions. In addition, dynamic contrast-enhanced ultrasound (DCE-US) provides valuable information concerning perfusion of examined organs. This review addresses current applications of CEUS in children, focused on DCE-US of the bowel wall in patients with Crohn disease, which enables realtime assessment of the bowel wall vascularity with semi-quantitative and quantitative assessment of disease activity and response to medical treatment.

Conclusions

Crohn’s disease is a chronic inflammatory relapsing disease. Frequent imaging re-evaluation is necessary. Therefore, imaging should be as little invasive as possible, children friendly with high diagnostic accuracy. US with wide varieties of techniques, including CEUS/DCE-US, can provide an important contribution for diagnosing and monitoring a disease activity. Even if the use of US contrast agent is off-label in children, it is welcome and widely accepted for intravesical use, and a little less for intravenous use, manly in evaluation of parenchymal lesions. To our knowledge this is the first time that the use of DCE-US in the evaluation of activity of small bowel Crohn disease with quantitative assessment of kinetic parameters is being described in children. Even if the results of the value and accuracy of different quantitative kinetic parameters in published studies in adult population often contradict one another there is a great potential of DCE-US to become a part of the entire sonographic evaluation not only in adults, but also in children. Further control studies should be performed.

Contrast-Enhanced Ultrasound in Focal Liver Lesions: Where Do We Stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in sonography, and it is being increasingly used for the evaluation of focal liver lesions (FLLs). Currently, CEUS is included as a part of the suggested diagnostic workup of FLLs, resulting in a better patient management and delivering cost-effective therapy. After a brief technical note, contrast-enhancement patterns of different types of benign and malignant FLLs, along with hepatic pseudolesions, are described and discussed based on our experience and literature data. At the same time, the most recent concepts and the use of CEUS in different clinical settings are presented.

Enhancing the role of paediatric ultrasound with microbubbles: a review of intravenous applications

Contrast-enhanced ultrasound (CEUS) represents a complementary technique to greyscale and colour Doppler ultrasonography which allows for real-time visualization and characterization of tissue perfusion. Its inherent advantages in the child makes ultrasonography an ideal imaging modality; repeatability and good tolerance along with the avoidance of CT, a source of ionizing radiation, renders ultrasonography imaging desirable. Although currently paediatric CEUS is principally used in an "off-label" manner, ultrasonography contrast agents have received regulatory approval for assessment of paediatric focal liver lesions (FLL) in the USA. The safety of ultrasound contrast-agents is well documented in adults, as safe as or even surpassing the safety profile of CT and MR contrast agents. Except for the established intracavitary use of CEUS in voiding urosonography, i.v. paediatric applications have been introduced with promising results in the abdominal trauma initial diagnosis and follow-up, characterization and differential diagnosis of FLL and characterization of lung, pleura, renal and splenic pathology. CEUS has also been used to detect complications after paediatric transplantation, evaluate inflammatory bowel disease activity and assess tumour response to antiangiogenic therapy. The purpose of this review was to present these novel i.v. paediatric applications of CEUS and discuss their value.

Particularities of Crohn's disease in pediatric patients: current status and perspectives regarding imaging modalities

A consensus on the best imaging modality evaluating inflammatory bowel disease in the pediatric population is lacking and it is often unclear which modality to choose in specific clinical circumstances. Children with inflammatory bowel disease are exposed to ionizing radiation from multiple imaging studies performed at initial diagnosis, throughout treatment and during the follow-up period. This paper discusses the value of different imaging techniques in pediatric patients with inflammatory bowel disease and gives a review of the literature. In addition, particular features of inflammatory bowel disease in children including the predilection of affected segments in the gastrointestinal tract are highlighted. Based on current literature knowledge, we encourage an integrative approach to the interpretation of clinical and imaging data for diagnosis and follow-up in daily clinical settings.

International guidelines for contrast-enhanced ultrasonography: ultrasound imaging in the new millennium

The intent of this review is to discuss and comment on common clinical scenarios in which contrast-enhanced ultrasonography (CEUS) may play a decisive role and to illustrate important points with typical cases. With the advent of CEUS, the scope of indications for ultrasonography has been dramatically extended, and now includes functional imaging and tissue characterization, which in many cases enable tumor diagnosis without a biopsy. It is virtually impossible to imagine the practice of modern medicine as we know it in high-income countries without the use of imaging, and yet, an estimated two thirds of the global population may receive no such care. Ultrasound imaging with CEUS has the potential to correct this inequity.

Use of contrast media in diagnostic imaging: medico-legal considerations

Contrast media (CM) are used in imaging techniques to enhance the differences between body tissues on images. The ideal contrast medium should achieve very high concentration in the tissues without producing any adverse effects. Unfortunately, this has not been possible so far and all CM have adverse effects. The increasing use of CM is likely to give rise to a wide range of pitfalls, including compliance with and appropriateness of indications for the use of CM themselves, the choice of the ‘best’ contrast agent, off-label use, evaluation of special populations of patients, and competence to tackle emergency scenarios following the administration of CM. Even more prominent, and potentially more important, is the issue of informed consent which brings with it a duty to inform patients awaiting the administration of CM with regard to the nature of the procedure, the existence of alternative procedures, the extent of the risks relating to the use of CM and, finally, the risks relating to refusal of the procedure. All these issues may give rise to concerns about liability for failure to offer adequate information to patients or to carefully evaluate and balance the potential risks and benefits of the procedure or, finally, for being unprepared in the event of adverse reactions to CM, especially when these are severe and life-threatening. Educational and training programmes for radiologists are likely to shape change in the medical liability environment in the coming years.