Detection of peripheral embolic consolidations using contrast-enhanced ultrasonography in patients with no evidence of pulmonary embolism on computed tomography: A pilot study

Comments and Illustrations of the European Federation of Societies for Ultrasound in Medicine (EFSUMB) Guidelines: Rare Malignant Pulmonal and Pleural Tumors: Primary Pulmonary Sarcoma and Mesothelioma, Imaging Features on Transthoracic Ultrasound

Primary pulmonary sarcoma and mesothelioma are rare malignancies. The review article discusses the appearance of these tumors in B-mode ultrasound (US), color Doppler ultrasound and contrast-enhanced ultrasound (CEUS). In particular, the article is intended to inspire the examination of thoracic wall tumors and pleural masses with the possibilities of ultrasonography and to obtain histologically evaluable material using US or CEUS-guided sampling.

Conventional and Contrast-enhanced US of the Lung: From Performance to Diagnosis

In recent years, lung US has evolved from a marginal tool to an integral component of diagnostic chest imaging. Contrast-enhanced US (CEUS) can improve routine gray-scale imaging of the lung and chest, particularly in diagnosis of peripheral lung diseases (PLDs). Although an underused tool in many centers, and despite inherent limitations in evaluation of central lung disease caused by high acoustic impedance between air and soft tissues, lung CEUS has emerged as a valuable tool in diagnosis of PLDs. Owing to the dual arterial supply to the lungs via pulmonary and bronchial (systemic) arteries, different enhancement patterns can be observed at lung CEUS, thereby enabling accurate differential diagnoses in various PLDs. Lung CEUS also assists in identifying patients who may benefit from complementary diagnostic tests, including image-guided percutaneous biopsy. Moreover, lung CEUS-guided percutaneous biopsy has shown feasibility in accessible subpleural lesions, enabling higher histopathologic performance without significantly increasing either imaging time or expenses compared with conventional US. The authors discuss the technique of and basic normal and pathologic findings at conventional lung US, followed by a more detailed discussion of lung CEUS applications, emphasizing specific aspects of pulmonary physiology, basic concepts in lung US enhancement, and the most commonly encountered enhancement patterns of different PLDs. Finally, they discuss the benefits of lung CEUS in planning and guidance of US-guided lung biopsy. ©RSNA, 2024 Supplemental material is available for this article.

Ultrasound of the lung

The CME review is intended to explain and discuss the clinical value of lung ultrasound but also to enable a pragmatically oriented approach by analyzing the clinical aspect. This includes knowledge of the pre-test probability, the acuteness of the disease, the current clinical situation, detection and/or characterization, initial diagnosis or follow up assessment and the peculiarities of exclusion diagnosis. Diseases of the pleura and lungs are described using these criteria with their direct and indirect sonographic signs and the specific clinical significance of ultrasound findings. The importance and criteria of conventional B-mode, color Doppler ultrasound with or without spectral analysis of the Doppler signal and contrast-enhanced ultrasound are discussed as well.

New International Guidelines and Consensus on the Use of Lung Ultrasound

Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.

Peripheral Pulmonary Lesions in Confirmed Pulmonary Arterial Embolism: Follow-up Study of B-Mode Ultrasound and of Perfusion Patterns Using Contrast-Enhanced Ultrasound (CEUS)

PURPOSE

This retrospective study aimed to describe the B-mode lung ultrasound (B-LUS) and contrast-enhanced ultrasound (CEUS) follow-up patterns of peripheral pulmonary lesions (PPLs) in patients with confirmed pulmonary embolism (PE).

PATIENTS AND METHODS

Data from 27 patients with a confirmed diagnosis of PE and PPLs over 5 mm from October 2009 to November 2018 were included retrospectively in the study. The inclusion criteria were performance of a baseline CEUS examination, a short-term B-LUS and CEUS follow-up, and a long-term B-LUS follow-up of PPLs. The homogeneity of enhancement of PPLs (homogeneous/inhomogeneous/absent) on CEUS and the presence and size of PPLs on B-LUS were evaluated.

RESULTS

A total of n = 25/27 (92.6%) lesions showed absent or inhomogeneous enhancement during baseline examination or short-term follow-up, indicating impaired perfusion. On short-term CEUS follow-up, 9/27 cases (33.3%) showed a pattern shift. On B-LUS long-term follow-up, 26/27 lesions (96.3%) were detectable for an average of 10 weeks (range 3-32 weeks). The size of reference lesions was significantly reduced at the time of the final follow-up examination (P < .05).

CONCLUSION

B-LUS follow-up showed that, in patients with confirmed PE, PPLs had a delayed regression. On CEUS follow-up examination, various perfusion patterns of PPLs were observed, indicating the different ages and the variable reparative processes of pulmonary infarction. In PPLs independent of the underlying signs and symptoms, follow-up B-LUS and CEUS examinations may be helpful for a possible retrospective diagnosis of peripheral pulmonary infarction suggestive of PE.

Lung aeration, ventilation, and perfusion imaging

PURPOSE OF REVIEW

Lung imaging is a cornerstone of the management of patients admitted to the intensive care unit (ICU), providing anatomical and functional information on the respiratory system function. The aim of this review is to provide an overview of mechanisms and applications of conventional and emerging lung imaging techniques in critically ill patients.

RECENT FINDINGS

Chest radiographs provide information on lung structure and have several limitations in the ICU setting; however, scoring systems can be used to stratify patient severity and predict clinical outcomes. Computed tomography (CT) is the gold standard for assessment of lung aeration but requires moving the patients to the CT facility. Dual-energy CT has been recently applied to simultaneous study of lung aeration and perfusion in patients with respiratory failure. Lung ultrasound has an established role in the routine bedside assessment of ICU patients, but has poor spatial resolution and largely relies on the analysis of artifacts. Electrical impedance tomography is an emerging technique capable of depicting ventilation and perfusion at the bedside and at the regional level.

SUMMARY

Clinicians should be confident with the technical aspects, indications, and limitations of each lung imaging technique to improve patient care.

WFUMB Technological Review: How to Perform Contrast-Enhanced Ultrasound of the Lung

The use of ultrasound has revolutionized the evaluation of pulmonary complaints and pathology. Historically, most lung ultrasound uses described are limited to B-mode, M-mode and occasionally color Doppler. However, the use of contrast can significantly expand the diagnostic capabilities of lung ultrasound. Ultrasound contrast enables significant expansion of therapeutic and intervention capabilities. We provide a detailed description of contrast administration, phases and uses in lung ultrasound. Additionally provided are example contrast use cases and illustrative examples of contrast use in a wide range of lung ultrasound applications including pneumonia, atelectasis, pulmonary embolism and neoplasms. Clinical practice examples will help providers incorporate contrast use into their lung ultrasound practice.

Clinical Applications of Contrast-Enhanced Thoracic Ultrasound (CETUS) Compared to Standard Reference Tests: A Systematic Review

INTRODUCTION

 Contrast-enhanced ultrasound is utilized in an increasing array of medical fields, including thoracic medicine. However, the technique is still relatively new and only sporadically mentioned in current guidelines and recommendations. The aim of this systematic review is to provide a literature overview and to critically appraise the current clinical applications of contrast-enhanced thoracic ultrasound (CETUS).

MATERIALS AND METHODS

 A systematic literature search using major electronic databases and in accordance with PRISMA guidelines was performed. Studies with a primary focus on CETUS of thoracic disorders compared to a standard reference test were included. The QUADAS-2 tool was used for quality assessment of the studies.

RESULTS

 The search identified 43 articles: 1 randomized controlled study, 6 non-randomized controlled studies, 16 non-randomized non-controlled studies, 5 case series, 10 single case reports, and 5 animal studies. The overall risk of bias was judged to be high. Diagnostic accuracy measurements of noninvasive applications of CETUS were only reported in a few studies and they were too dissimilar for meta-analysis. Six studies compared CETUS-guided versus ultrasound-guided transthoracic needle biopsy of thoracic masses. They individually reported a significant increase in diagnostic accuracy in favor of CETUS guidance but were too heterogeneous for meta-analysis.

CONCLUSION

 The current literature on CETUS is overall heterogeneous with a few high evidence level studies, small study populations and a high risk of bias. CETUS-guided biopsy is the most frequent clinical application and increases diagnostic accuracy compared to ultrasound guidance by an average of 14.6 percentage points.

[Standardized contrast-enhanced ultrasound (CEUS) in clinical acute and emergency medicine and critical care (CEUS Acute) : Consensus statement of DGIIN, DIVI, DGINA, DGAI, DGK, ÖGUM, SGUM and DEGUM]

The present document describes the possible applications of contrast-enhanced ultrasound (CEUS) in emergency examinations. Guidelines on contrast medium ultrasound in acute and emergency care and intensive care medicine have not yet been published. Evidence-based CEUS guidelines were first provided by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) and the World Federation for Ultrasound in Medicine and Biology (WFUMB). The presented recommendations describe the possible applications and protocols of CEUS in acute care.

Perfusion Patterns of Peripheral Pulmonary Lesions in COVID-19 Patients Using Contrast-Enhanced Ultrasound (CEUS): A Case Series

PURPOSE

To describe perfusion patterns of peripheral pulmonary lesions (PPLs) in COVID-19 patients using contrast-enhanced ultrasound (CEUS).

PATIENTS AND METHODS

From April 2020 until July 2020, 11 consecutive patients with RT-PCR-confirmed COVID-19 and PPLs sized over 5 mm were investigated by B-mode ultrasound (B-US) and CEUS. The homogeneity of enhancement (homogeneous and inhomogeneous) was examined retrospectively using CEUS. An inhomogeneous enhancement was defined as a perfused lesion with coexisting non-perfused areas (NPA).

RESULTS

On B-US, all 11 patients showed an interstitial syndrome (B-lines) with PPLs between 0.5 and 6 cm. On CEUS, all cases showed peripheral NPA during the complete CEUS examination. One patient underwent a partial lung resection with subsequent histopathological examination. The histological examination showed vasculitis, microthrombus in the alveolar capillary, and small obliterated vessels.

CONCLUSION

In our case series, PPLs in patients with RT-PCR-confirmed COVID-19 infection presented a CEUS pattern with NPA during the complete CEUS examination. Our findings suggest a peripheral pulmonary perfusion disturbance in patients with COVID-19 infection. In 1 case, the histopathological correlation with the perfusion disturbance in the PPL was proven.

Perfusion Patterns of Peripheral Organizing Pneumonia (POP) Using Contrast-Enhanced Ultrasound (CEUS) and Their Correlation with Immunohistochemically Detected Vascularization Patterns

Purpose: To describe the perfusion patterns of peripheral organizing pneumonia (POP) by contrast-enhanced ultrasound (CEUS) and their correlation with vascularization patterns (VPs) represented by immunohistochemical CD34 endothelial staining. Methods: From October 2006 until December 2020, 38 consecutive patients with histologically confirmed POPs were standardized-examined by CEUS. The time to enhancement (TE; classified as an early pulmonary-arterial [PA] pattern of enhancement vs. delayed bronchial-arterial [BA] pattern of enhancement), the extent of enhancement (EE; classified as marked or reduced), the homogeneity of enhancement (HE; classified as homogeneous or inhomogeneous), and the decrease of enhancement (DE; classified as rapid washout [<120s] or late washout [≥120s]) were evaluated retrospectively. Furthermore, tissue samples from the study patients were immunohistochemically stained with CD34 antibody. The presence of avascular areas (AAs) and the VPs were evaluated in all tissue samples. Results: The majority of POPs showed a BA pattern of enhancement (71.1%), an isoechoic marked enhancement (76.3%), and an inhomogeneous enhancement (81.6%). A rapid DE was observed in 50.0% of cases. On CD34 staining, all POPs had a chaotic VP, indicating BA neoangiogenesis. AAs (abscess, necrosis, hemorrhage) were identified in (41.9%) cases with an inhomogeneous enhancement on CEUS. Conclusion: On CEUS, POPs predominantly revealed a marked inhomogeneous BA pattern of enhancement with a rapid washout in 50% of cases. Furthermore, we demonstrated that the presence of a PA pattern of enhancement, found in 28.9% of POPs, did not exclude a BA neoangiogenesis as an important feature of chronic inflammatory and malignant processes.

Mediastinal Masses in Contrast-Enhanced Ultrasound - Retrospective Analysis of 58 Cases

OBJECTIVES

To determine contrast enhancing features of mediastinal masses (ML) using transcutaneous contrast-enhanced ultrasound (CEUS).

METHODS

Retrospective analysis of n = 58 patients with histologically confirmed ML, which were examined in the period from October 2005 to February 2018 using transcutaneous B-mode ultrasound and CEUS. In n = 29 (50%) histological confirmation was performed by ultrasound guided core-needle biopsy. The lesions were evaluated using CEUS in regard to the enhancement pattern (hyper-, iso-, hypoenhancement, non-enhancement, homogenous, inhomogenous) compared to enhancement of the spleen as an in vivo reference.

RESULTS

N = 53 (91.4%) of ML were malignant (m) (lymphoma n = 36, metastasis n = 11, thymoma n = 2, teratoma n = 1, sarcoma n = 2, seminoma n = 1). In n = 5 (8.6%) cases there was a benign (b) histology (thyroid tissue n = 2, thymus residue n = 1, ganglioneurinoma n = 1, scar tissue: n = 1). In ultrasound, n = 53 (91.4%; (48 = m, 5 = b)) were hypoechoic, n = 5 (8.6%, (5 = m,0 = b)) hyperechoic. In CEUS, n = 35 lesions presented an arterial isoenhancement (60.3%; 33 = m, 2 = b). An arterial hypoenhancement had n = 21 (36.2%, (20 = m,1 = b)), and no enhancement showed n = 2 (3.5%, (0 = m, 2 = b) of the ML. A parenchymal isoenhancement was observed in n = 1 (1.7%, (1 = m, 0 = b)), a hypoenhancement in n = 54 (93.1%; 51 = m, 3 = b) of the patients and almost no enhancement in n = 3 ML (5.2%, (1 = m, 2 = b).) The enhancement was homogeneous in n = 26 (44.8%, (25 = m,1 = b)) cases, in n = 31 (53.5%, (28 = m,3 = b)) inhomogeneous and n = 1 (1.7%) benign lesion was exclusively cystic.

CONCLUSION

In CEUS, mediastinal tumor formations showed variable arterial enhancement, followed by parenchymal hypoenhancement (wash-out).

Future developments in the imaging of the gastrointestinal tract: the role of ultrasound

PURPOSE OF REVIEW

The purpose of this review is to summarize the utilization and most recent developments with regard to the use of ultrasound when imaging the abdomen and gastrointestinal tract.

RECENT FINDINGS

Although the use of ultrasound to assess the anatomy of the various abdominal organs is well established within radiology and critical care, its use as part of functional and physiological assessment is still evolving. Recent developments have extended the use of ultrasound beyond standard B-mode/2D imaging techniques to incorporate more functional and haemodynamic assessment. These include the use of contrast-enhanced ultrasound (CEUS), elastography, and colour Doppler techniques.

SUMMARY

Whilst Doppler techniques are reasonably well established within critical care ultrasound (CCUS), especially in echocardiography, CEUS and elastography are less well known. CEUS utilizes a purely intravascular contrast agent whilst elastography measures the degree of deformation or stiffness in various organs. Whilst their use individually may be limited; they may play a role in a multiparametric assessment. Mirroring the overall trends in critical care ultrasound development, abdominal ultrasound assessment is best integrated in a holistic approach and adapted to the individual patient.

Combining lung ultrasound and Wells score for diagnosing pulmonary embolism in critically ill COVID-19 patients

Subpleural consolidations have been found in lung ultrasound in patients with COVID-19, possibly deriving from pulmonary embolism (PE). The diagnostic utility of impact of lung ultrasound in critical-ill patients with COVID-19 for PE diagnostics however is unclear. We retrospectively evaluated all SARS-CoV2-associated ARDS patients admitted to our ICU between March 8th and May 31th 2020. They were enrolled in this study, when a lung ultrasound and a computed tomography pulmonary angiography (CTPA) were documented. In addition, wells score was calculated to estimate the probability of PE. The CTPA was used as the gold standard for the detection of PE. Twenty out of 25 patients met the inclusion criteria. In 12/20 patients (60%) (sub-) segmental PE were detected by CT-angiography. Lung ultrasound found subpleural consolidations in 90% of patients. PE-typical large supleural consolidations with a size ≥ 1 cm were detectable in 65% of patients and were significant more frequent in patients with PE compared to those without (p = 0.035). Large consolidations predicted PE with a sensitivity of 77% and a specificity of 71%. The Wells score was significantly higher in patients with PE compared to those without (2.7 ± 0.8 and 1.7 ± 0.5, respectively, p = 0.042) and predicted PE with an AUC of 0.81. When combining the two modalities, comparing patients with considered/probable PE using LUS plus a Wells score ≥ 2 to patients with possible/unlikely PE in LUS plus a Wells score < 2, PE could be predicted with a sensitivity of 100% and a specificity of 80%. Large consolidations detected in lung ultrasound were found frequently in COVID-19 ARDS patients with pulmonary embolism. In combination with a Wells score > 2, this might indicate a high-risk for PE in COVID-19.

Contrast enhanced ultrasound (CEUS) to assess pleural pulmonal changes in severe COVID-19 infection: First results

AIM:

Use of contrast enhanced ultrasound (CEUS) in severe cases of COVID-19 infection to assess pulmonary changes near the pleura.

MATERIAL AND METHODS:

Bedside examinations by an experienced intensive care unit examiner using a multi-frequency probe (C1-6 MHz) with B-mode and CEUS to assess pleural-near changes in severe cases of COVID-19 infection with respiratory failure. CEUS with bolus delivery via a central venous catheter of 2.4 ml Sulphur hexafluoride microbubbles from the arterial phase (10–15 s) to the late phase of 5 min. Digital storage of cine sequences of the lung sound with abdomen for independent assessment with the subsequently performed contrast-enhanced dual-source CT.

RESULTS:

In 11 intubated and ventilated patients (arithmetic mean 62 years, 48 to 78 years, 3 women) with confirmed severe COVID-19 infections, a peripherally accentuated consolidation with irregular hyperemia was found in the CEUS and also in the CT examination. Of the 5 cases with pulmonary arterial embolisms, signs of right ventricular failure were found. In all cases, using CEUS low perfused areas of the pleura with adjacent hyperemia could be detected, while, with CT segmental contrast medium, gaps with subpleural compressions were found. Interstitial changes near the pleura led to B-lines and to ground glass opacities in the CT. Near the diaphragm a delayed arterial contrast of the liver was observed. In addition, in 2 cases partial atelectasis, in 3 cases marginal pleural effusions were found.

CONCLUSION:

CEUS opens up new possibilities for bedside monitoring of pleural reactive inflammatory or peripheral thrombus embolism in severe cases of COVID-19 infection.

Application of quantitative contrast-enhanced ultrasound for evaluation and guiding biopsy of peripheral pulmonary lesions: a preliminary study

AIM

To evaluate the usefulness of contrast-enhanced ultrasonography (CEUS) in differentiating malignant from benign peripheral pulmonary lesions, and to evaluate the feasibility, accuracy, and utility of CEUS-guided biopsy for peripheral pulmonary lesions.

MATERIALS AND METHODS

Thirty-three patients with histopathologically confirmed peripheral pulmonary lesions (22 malignant, 11 benign) were enrolled in this retrospective study. Conventional ultrasound (US) was first performed and then CEUS with a contrast-specific mode and sulfur hexafluoride-filled microbubble contrast agent. CEUS indices-time of enhancement (TE), time to peak (TP), extent of peak (EP), mean transit time (MTT), area under curve (AUC), and slope-were recorded and compared between the groups. The ability of CEUS and US to detect necrotic areas within lesions was also compared and the accuracy of CEUS-guided biopsy was calculated.

RESULTS

On CEUS, TE was significantly shorter in acute pneumonia lesions than in other types of lesions (p=0.03). Other indices were not significantly different between benign and malignant lesions. Detection of necrosis within lesions was significantly higher with CEUS than with US (51.5% versus 27.3%; p=0.04). The accuracy of CEUS-guided biopsy was 96.9% (32/33).

CONCLUSION

The study findings suggest that CEUS can identify necrotic areas within lesions, and thereby, play a useful role in imaging-guided biopsy. The present pilot study indicates that CEUS may help to identify acute pneumonia lesions from other types of pulmonary lesions. CEUS might be a useful additional technique for the diagnosis of lung lesions.

Histological validation of pulmonary infarction detected with contrast-enhanced ultrasound in patients with negative computed tomography pulmonary angiogram: A case series

OBJECTIVE

The purpose of this case series is to evaluate the diagnostic potential of contrast-enhanced ultrasound (CEUS) in patients with clinically suspected pulmonary embolism (PE), suspicious pleural lesions, and negative computed tomography pulmonary angiogram (CTPA).

PATIENTS/METHODS

Between January 2017 and January 2018, we examined patients with an intermediate or a high-risk Wells score and a negative CTPA with lung B-mode ultrasound (LUS). In a total of six patients, pleural defects were identified and further examined by CEUS. Nonenhancing lesions or those with inhomogeneous enhancement were considered to be suspicious for an embolic event and biopsied for histological validation. The data analysis was retrospective.

RESULTS

In LUS, the lesions had an average size of 2.4 cm (range 2-3 cm). Five were hypoechoic and one was complex. The shape was wedge shaped (n = 5) or round (n = 1), and the number was solitary (n = 4) or multiple (n = 2) with dorsobasal localization (n = 6). Three lesions were nonenhancing, and three had an inhomogeneous enhancement with areas with complete absence of enhancement. The histological examination showed pulmonary infarction in all six cases, and in one patient also cells of a lung carcinoma.

CONCLUSION

Our case series demonstrates the diagnostic potential of CEUS for detecting peripheral pulmonary infarction in patients with clinically suspected PE and negative CTPA scan regarding PE. A histological validation or a narrow follow-up might be warranted in some cases.

Emergency and critical care applications for contrast-enhanced ultrasound

INTRODUCTION

Contrast-enhanced ultrasound (CEUS) using intravascular microbubbles has potential to revolutionize point-of-care ultrasonography by expanding the use of ultrasonography into clinical scenarios previously reserved for computed tomography (CT), magnetic resonance imaging, or angiography.

METHODS

We performed a literature search and report clinical experience to provide an introduction to CEUS and describe its current applications for point-of-care indications.

RESULTS

The uses of CEUS include several applications highly relevant for emergency medicine, such as solid-organ injuries, actively bleeding hematomas, or abdominal aortic aneurysms. Compared with CT as the preeminent advanced imaging modality in the emergency department, CEUS is low cost, radiation sparing, repeatable, and readily available. It does not require sedation, preprocedural laboratory assessment, or transportation to the radiology suite.

CONCLUSIONS

CEUS is a promising imaging technique for point-of-care applications in pediatric and adult patients and can be applied for patients with allergy to CT contrast medium or with impaired renal function. More high-quality CEUS research focusing on accuracy, patient safety, health care costs, and throughput times is needed to validate its use in emergency and critical care settings.