"Fluid color" sign: a useful indicator for discrimination between pleural thickening and pleural effusion

Lung ultrasound in a nutshell. Lines, signs, some applications, and misconceptions from a radiologist's point of view. Part 2

In recent years, lung ultrasound (LUS) has developed rapidly, and it is gaining growing popularity in various scenarios. There are constant attempts to introduce it to new fields. In addition, knowledge regarding lung and LUS has been augmented by the recent COVID-19 pandemics. In the first part of this review we discuss lines, signs and pheno-mena, profiles, some applications, and misconceptions. An aim of the second part of the review is mainly to discuss some advanced applications of LUS, including lung elastography, lung spectroscopy, colour and spectral Doppler, contrast-enhanced ultrasound of lung, speckled tracking of pleura, quantification of pulmonary oedema, predicting success of talc pleurodesis, asthma exacerbations, detecting chest wall invasion by tumours, lung biopsy, estimating pleural effusion volume, and predicting mechanical ventilatory weaning outcome. For this purpose, we reviewed literature concerning LUS.

Thoracic ultrasound use in hospitalized and ambulatory adult patients: a quantitative picture

INTRODUCTION AND OBJECTIVES

Thoracic ultrasound (TUS) has been established as a powerful diagnostic and monitoring tool in the Intensive Care Unit (ICU). However, studies outside the critical care setting are scarce. The aim of this study was to investigate the value of TUS for hospitalized or ambulatory community patients.

MATERIALS AND METHODS

This was a retrospective study conducted from 2016 to 2020 in the TUS clinic at Heraklion University Hospital. TUS examination was performed using a standard ultrasound machine (EUB HITACHI 8500), and a high-frequency microconvex probe (5-8 MHz). Patients had been referred by their primary physician to address a range of different questions. The various respiratory system entities were characterised according to internationally established criteria.

RESULTS

762 TUS studies were performed on 526 patients due to underlying malignancy (n = 376), unexplained symptoms/signs (n = 53), pregnancy related issues (n = 42), evaluation of abnormal findings in X-ray (n = 165), recent surgery/trauma (n = 23), recent onset respiratory failure (n = 12), acute respiratory infection (n = 66) and underlying non-malignant disease (n = 25). Pleural effusion was the commonest pathologic entity (n = 610), followed by consolidation (n = 269), diaphragmatic dysfunction/paradox (n = 174) and interstitial syndrome (n = 53). Discrepancies between chest X-ray and ultrasonographic findings were demonstrated in 96 cases. The TUS findings guided invasive therapeutic management in 448 cases and non-invasive management in 43 cases, while follow-up monitoring was decided in 271 cases.

CONCLUSIONS

This study showed that TUS can identify the most common respiratory pathologic entities encountered in hospitalized and community ambulatory patients, and is especially useful in guiding the decision making process in a diverse group of patients.

Considerations for Imaging of Malignant Pleural Mesothelioma: A Consensus Statement from the International Mesothelioma Interest Group

Malignant pleural mesothelioma (MPM) is an aggressive primary malignancy of the pleura that presents unique radiologic challenges with regard to accurate and reproducible assessment of disease extent at staging and follow-up imaging. By optimizing and harmonizing technical approaches to imaging MPM, the best quality imaging can be achieved for individual patient care, clinical trials, and imaging research. This consensus statement represents agreement on harmonized, standard practices for routine multimodality imaging of MPM, including radiography, computed tomography, ¹⁸F-2-deoxy-D-glucose positron emission tomography, and magnetic resonance imaging, by an international panel of experts in the field of pleural imaging assembled by the International Mesothelioma Interest Group. In addition, modality-specific technical considerations and future directions are discussed. A bulleted summary of all technical recommendations is provided.

Ultrasound for Pleural Disease. Beyond a Pocket of Pleural Fluid

The evolution of pleural disease imaging modalities through the years has helped the scientific community understand and treat various disease states. Ultrasound (US) has been an image modality that has reigned superior to those used in the past such as chest X-ray and computed tomographic scan in terms of cost effectiveness, portability, and reduction in unwarranted radiation exposure to patients. Here we provide a succinct review of US use in pleural disease including imaging techniques, identifying safe pleural space for access, and predicting pleural fluid volume and etiology along with specificities regarding trapped lung identification and pleural mass biopsy. We believe bedside chest US is an adjunct to the physical exam adding superior diagnostic abilities. Further research is warranted in more specific aspects of sonographic use such as in fibrinolytic therapy management, evaluation for trapped lung, and the utility of specific modes like the color flow Doppler.

Point-of-Care Ultrasound in the Intensive Care Unit

Spreading beyond the realm of tertiary academic medical centers, point-of-care ultrasound in the intensive care unit is an important diagnostic tool. The real-time feedback garnered can lead to critical and clinically relevant changes in management and decrease potential complications. Bedside ultrasound evaluation in the intensive care setting with a small, portable equipment is well-suited for placement of central lines, lumbar puncture, thoracentesis or other bedside ICU procedures and in the evaluation of cardiac activity, pleural and abdominal cavity and the overall fluid volume. Formalized curriculums centering on point-of-care ultrasound are emerging that will enhance its applicability and relevance.

New insights in the use of pleural ultrasonography for diagnosis and treatment of pleural disease

The use of transthoracic ultrasound (US) has acquired a wide consensus among respiratory physicians during the last few years. The development of portable devices promotes patient's bedside evaluation providing rapid, real-time and low-cost diagnostic information. The different acoustic impedance between different tissues and organs produces artifacts known as A lines, B lines, sliding sign, lung point, etc. The identification of such artifacts is essential to discriminate normal pleural appearance from the presence of pleural effusion, pneumothorax, thickenings and tumors. Ultrasounds are also a valuable tool during interventional procedures, such as thoracentesis, chest tube insertion and transcutaneous biopsy. Its use is recommended before medical thoracoscopy in order to assess the best site of trocar insertion according to presence, quantity and characteristics of pleural effusion. The aim of this review is to provide practical tips on chest ultrasound in clinical and interventional respiratory practice.

The efficacy of bedside chest ultrasound: from accuracy to outcomes

For many respiratory physicians, point-of-care chest ultrasound is now an integral part of clinical practice. The diagnostic accuracy of ultrasound to detect abnormalities of the pleura, the lung parenchyma and the thoracic musculoskeletal system is well described. However, the efficacy of a test extends beyond just diagnostic accuracy. The true value of a test depends on the degree to which diagnostic accuracy efficacy influences decision-making efficacy, and the subsequent extent to which this impacts health outcome efficacy. We therefore reviewed the demonstrable levels of test efficacy for bedside ultrasound of the pleura, lung parenchyma and thoracic musculoskeletal system.For bedside ultrasound of the pleura, there is evidence supporting diagnostic accuracy efficacy, decision-making efficacy and health outcome efficacy, predominantly in guiding pleural interventions. For the lung parenchyma, chest ultrasound has an impact on diagnostic accuracy and decision-making for patients presenting with acute respiratory failure or breathlessness, but there are no data as yet on actual health outcomes. For ultrasound of the thoracic musculoskeletal system, there is robust evidence only for diagnostic accuracy efficacy.We therefore outline avenues to further validate bedside chest ultrasound beyond diagnostic accuracy, with an emphasis on confirming enhanced health outcomes.

Ultrasound in the management of pleural disease

INTRODUCTION

Pleural disease encompasses a large range of conditions, is a common presentation to the acute medical take and often requires comprehensive investigation and treatment. Ultrasound is well recognised as a useful investigative tool in pleural disease especially in the field of pleural effusion, pleural thickening and interventional procedures. Thoracic ultrasound (TUS) has gained widespread use by physicians as evidence has shown a reduced rate of complications when performing pleural procedures with ultrasound guidance. Areas covered: This article will review studies assessing the role of TUS in the management of pleural disease and examine ongoing research into how TUS could advance our knowledge and understanding over the next decade. Expert commentary: Physician lead thoracic ultrasound has become commonplace over the last decade, and now represents a minimum standard of safety in conducting the majority of 'bedside' pleural procedures. The current evidence points to important diagnostic and procedural roles of the use of bedside thoracic ultrasound. In the future, research developments are likely to lead to the use of thoracic ultrasound in prognostication, targeted treatment and understanding pathogenesis in pleural disease.

Thoracic Ultrasound: What Non-radiologists Need to Know

Purpose of review

The aim of this review is to provide the theoretical and practical knowledge essential for non-radiologists to develop the skills necessary to apply thoracic ultrasound as an extension of clinical assessment and intervention.

Recent findings

Issues relating to training and competence are discussed and a library of thoracic ultrasound videos is provided to illustrate artefacts, pleural, parenchymal and pneumothorax pathology as well as important pitfalls to consider. Novel and future diagnostic applications of thoracic ultrasound in the setting of acute cardiorespiratory pathology including consolidation, acute interstitial syndromes and pulmonary embolism are explored.

Summary

Thoracic ultrasound requires an understanding of imaging artefact specific to lung and pleura and a working knowledge of machine knobology for image optimisation and interpretation. Ultrasound is a valuable tool for the practicing chest clinician providing diagnostic information for the assessment of pleural and parenchymal disease and increased safety and cost effectiveness of thoracic interventions.

Electronic supplementary material

The online version of this article (doi:10.1007/s13665-017-0164-1) contains supplementary material, which is available to authorized users.

Ultrasound in the diagnosis and management of pleural effusions

We review the literature on the use of point-of-care ultrasound to evaluate and manage pleural effusions. Point-of-care ultrasound is more sensitive than physical exam and chest radiography to detect pleural effusions, and avoids many negative aspects of computerized tomography. Additionally, point-of-care ultrasound can assess pleural fluid volume and character, revealing possible underlying pathologies and guiding management. Thoracentesis performed with ultrasound guidance has lower risk of pneumothorax and bleeding complications. Future research should focus on the clinical effectiveness of point-of-care ultrasound in the routine management of pleural effusions and how new technologies may expand its clinical utility.

Ultrasound of the pleurae and lungs

The value of ultrasound techniques in examination of the pleurae and lungs has been underestimated over recent decades. One explanation for this is the assumption that the ventilated lungs and the bones of the rib cage constitute impermeable obstacles to ultrasound. However, a variety of pathologies of the chest wall, pleurae and lungs result in altered tissue composition, providing substantially increased access and visibility for ultrasound examination. It is a great benefit that the pleurae and lungs can be non-invasively imaged repeatedly without discomfort or radiation exposure for the patient. Ultrasound is thus particularly valuable in follow-up of disease, differential diagnosis and detection of complications. Diagnostic and therapeutic interventions in patients with pathologic pleural and pulmonary findings can tolerably be performed under real-time ultrasound guidance. In this article, an updated overview is given presenting not only the benefits and indications, but also the limitations of pleural and pulmonary ultrasound.

Basic principles and current applications of lung ultrasonography in the intensive care unit

Until recently, the sonographic visualization of pulmonary and pleural diseases was considered a poorly accessible method, due to the inability of sound to penetrate air-filled lung. Despite its limitations, lung ultrasonography is becoming an important diagnostic tool in a growing number of pathological situations such as pneumonia, atelectasis, interstitial-alveolar syndrome, pulmonary embolism, pneumothorax and pleural effusion. The low sensitivity of CXR and the difficulties of performing CT make this technique invaluable for bedside use in the intensive care unit. Lung ultrasonography is an easily repeatable and radiation-free technique, and therefore, an attractive imaging tool for use on a daily basis, especially in the management of critically ill patients.

A systematic approach to the investigation and diagnosis of a unilateral pleural effusion

Fluid in the pleural space is a common sequela of a wide range of diseases which may be pulmonary, pleural or extrapulmonary. As the differential diagnosis is wide, a systematic approach to investigation and diagnosis is recommended. This review highlights the important features and recommendations for the investigation of a unilateral pleural effusion, a common condition encountered by the general physician. The aim of this study was to assist with a speedy diagnosis of the underlying pathology, using appropriate investigative techniques, while minimising the use of invasive procedures.

Pleural effusions in a series of 181 outpatients with sarcoidosis

OBJECTIVES

Pleural effusion (PE) is considered to be a rare manifestation of pulmonary sarcoidosis. We performed thoracic ultrasonography prospectively in consecutive outpatients with sarcoidosis to determine the frequency of PEs caused by sarcoidosis and to define their pleural fluid characteristics.

DESIGN

Consecutive outpatients aged >/= 18 years with biopsy-proven sarcoidosis underwent ultrasonography.

SETTING

University hospital, outpatient sarcoidosis clinic.

RESULTS

One hundred eighty-one outpatients were enrolled into the study. The subjects were predominately African-American and female. Most were between 30 and 60 years of age. The Scadding radiograph stages were fairly evenly distributed across all five stages (0 through 4). Five (2.8%) of 181 patients were found to have pleural fluid. Two patients had a unilateral left-sided PE, and three patients had bilateral PEs. Pleural fluid analysis (PFA) was performed in four patients. The PFA showed a lymphocyte-predominant exudate using protein criterion in only two patients, which is consistent with sarcoidosis-related PE; one patient underwent pleural biopsy, which was consistent with the diagnosis of sarcoidosis. A sarcoidosis-related PE was seen in 1 of 9 patients (11.1%) who had an exacerbation of pulmonary sarcoidosis compared to 1 of 172 patients (0.6%) who did not have an exacerbation (p < 0.4).

CONCLUSION

PEs are rare in outpatients with sarcoidosis, even when a sensitive technique, such as ultrasonography, is used. The frequency of PEs was 2.8% (5 of 181 patients) with only 2 of the 181 PEs (1.1%) caused by sarcoid pleural involvement. PE in patients with sarcoidosis should not be assumed to be related to sarcoidosis. Discordance between levels of pleural fluid total protein and lactate dehydrogenase may be a characteristic finding in patients with sarcoid PE. An exacerbation of pulmonary sarcoidosis was not an independent risk factor for the development of sarcoid-related PE.

Ultrasound-guided thoracentesis

Pleural effusions are an extremely common problem affecting approximately 1.5 million people in the United States each year. Over the last several years, the use of portable ultrasound machines has greatly enhanced the evaluation and management of patients with pleural disease. This article will review the relevant literature supporting the use of ultrasound for the evaluation of patients with pleural disease and address some practical practice management issues regarding ultrasonography.

Pediatric chest ultrasound

Ultrasound examination of the thorax can be quite rewarding in children, because their unique thoracic anatomy provides many acoustic windows into the chest. With only a modest effort, chest ultrasonography can provide many clinically relevant answers, without the radiation exposure from CT, or the need for sedation sometimes required for CT and MR imaging.

Radiology in pleural disease: State of the art

Diseases of the pleura and pleural space are common and present a significant contribution to the workload of the chest radiologist. The radiology department plays a crucial role in the imaging and management of pleural disease. This review aims to describe and illustrate the appearances of common pleural pathologies on various radiological modalities including plain film, ultrasound, CT, magnetic resonance imaging and positron emission tomography. The review will also address the state-of-the-art techniques used to image pleural disease and discuss image-guided intervention in the management of pleural disease.

Surgeon-performed ultrasound in the ICU setting

Evaluation of critically ill patients is often challenging due to altered sensorium, underlying disease, and the presence of multiple drains or monitoring devices. In such circumstances, the ability of physicians to perform ultrasound examinations in the intensive care unit provides a useful diagnostic and therapeutic adjunct. In this article,we review the application of surgeon-performed ultrasonography in the evaluation and management of critically ill patients.

Ultrasound in the diagnosis and management of pleural disease

The authors summarize the current applications of chest ultrasonography in the diagnosis and management of various pleural diseases. Ultrasound has been proved to be valuable for the evaluation of a wide variety of chest diseases, particularly when the pleural cavity is involved. Chest ultrasound can supplement other imaging modalities of the chest and guides a variety of diagnostic and therapeutic procedures. Pleural effusion, pleural thickening, pleural tumors, tumor extension into the pleura and even the chest wall, pleuritis, and pneumothorax can be detected easily and accurately with chest ultrasound. Many ultrasound features and signs of these diseases have been well characterized and widely applied in clinical practice. Under real-time ultrasound guidance the success rates of invasive procedures on pleural diseases increase significantly whereas the risks are greatly reduced. The advantages of low-cost, bedside availability and no radiation exposure have made ultrasound an indispensable diagnostic tool in modern pulmonary medicine.

Chest sonography versus lateral decubitus radiography in the diagnosis of small pleural effusions

PURPOSE

The aim of this prospective study was to assess the value of chest sonography in the radiologic diagnosis of small pleural effusions (relative to expiratory lateral decubitus radiography) and to suggest gray-scale sonographic criteria for detecting the presence of small pleural effusions.

METHODS

Patients referred for abdominal or chest sonographic evaluation for various reasons were also examined for sonographic features of pleural effusion from May 1, 1997, until January 31, 2000. Patients who had evidence of small pleural effusions were included. Patients with no such evidence served as a control group. Subsequently, all patients underwent erect posteroanterior and expiratory lateral decubitus chest radiography.

RESULTS

On chest sonography, 52 patients were found to have small pleural effusions. The control group consisted of 17 patients. The mean thickness of the pleural effusion was 9.2 mm on sonography and 7.6 mm on expiratory lateral decubitus radiography (p < 0.01). Compared with radiologic examination, chest sonography had a positive predictive value of 92% in the diagnosis of small pleural effusions in our study population.

CONCLUSIONS

Chest sonography showed a high degree of accuracy relative to that of lateral decubitus chest radiography in the diagnosis of small pleural effusions, which appeared as thin (usually 15 mm thick or less) anechoic areas that changed shape with the phases of respiration.

Transthoracic US of the chest: clinical uses and applications

Transthoracic ultrasound (US) of the chest is useful in the evaluation of a wide range of peripheral parenchymal, pleural, and chest wall diseases. Furthermore, it is increasingly used to guide interventional procedures of the chest and pleural space. The technique lends itself to bedside use in the intensive care unit, where suboptimal radiography may mask or mimic clinically significant abnormalities. The authors discuss the uses, techniques and applications of US of the chest. The sonographic appearances of pleural diseases (pleural effusion, pneumothorax, pleural mass, and mesothelioma), parenchymal diseases (pneumonia, neoplasms, heart failure, infarct, and rounded atelectasis), chest wall abnormalities (chest wall tumor and rib fracture), and diaphragmatic paralysis are discussed. The use of US in guiding biopsy, thoracocentesis, and other interventional procedures of the lung, pleural space, and mediastinum are also reviewed.

US in the diagnosis of pediatric chest diseases

Most pediatric chest diseases are adequately evaluated with chest radiography. However, when chest radiography does not allow identification of the location and nature of an area of increased opacity, ultrasonography (US) can help establish the diagnosis. US may be helpful in evaluation of persistent or unusual areas of increased opacity in the peripheral lung, pleural abnormalities, and mediastinal widening; US is particularly useful in patients with complete opacification of a hemithorax at radiography. In cases of pulmonary parenchymal lesions, identification of air or fluid bronchograms at US and of pulmonary vessels at color flow imaging is useful for differentiating pulmonary consolidation or atelectasis from lung masses and pleural lesions. US allows characterization of pleural fluid collections as simple, complicated, or fibroadhesive, which is important information for planning thoracentesis or thoracotomy. Computed tomography and magnetic resonance imaging are superior to US in evaluation of the mediastinum, but US is a reasonable alternative in certain situations (eg, to avoid unnecessary investigation of a normal thymus simulating a mediastinal mass). In cases of chest wall lesions, US may enable localization of the site of origin to soft tissues or an extrapleural intrathoracic location. Osseous involvement, particularly rib involvement, is easily evaluated with US.

Applications of colour Doppler ultrasound in the diagnosis of chest diseases

Colour Doppler ultrasound (US) or colour Doppler imaging is a new imaging modality that can simultaneously display blood flow information and Doppler spectral analysis. This new technique provides an opportunity to assess pulmonary blood flow and perfusion non-invasively. Colour Doppler US has many potential applications in diseases of the chest. Colour Doppler imaging is useful in assisting the diagnosis of pulmonary arteriovenous malformation and pulmonary sequestration. The 'fluid colour sign' can be used to detect minimal effusion amenable to thoracentesis. Colour Doppler US can be used to assess the angiogenesis of a lung tumour and may be helpful in differentiating a malignant tumour from a benign one. Colour Doppler US can be used to guide a transthoracic needle biopsy and improve the safety of this invasive procedure. Colour Doppler US can demonstrate the vascular patterns and assess the regional haemodynamic changes of a pulmonary consolidation. The information of spectral wave analysis is helpful for understanding the haemodynamic changes of a pulmonary consolidation. Colour Doppler US is useful in assessing perfusion and reperfusion status of a pulmonary infarction. The recent advent of amplitude US angiography further improved the sensitivity of colour Doppler US in detecting blood flow signal without angle restriction. The potential application of these new techniques in chest diseases may need further exploration.

Thoracic sonography for diagnosis and intervention

Many physicians believe that ultrasound has limited usefulness in chest disease. Our clinical experiences and a review of the literature in preparation for this monograph have convinced us that sonography can be a very useful and versatile tool for thoracic diagnosis and intervention. Although there are some limitations caused by interposed ribs and air-containing lung, almost all of the compartments of the chest can be evaluated with ultrasound, which gives unique and clinically useful information. Ultrasound guidance for biopsy and drainage does take some time to learn, but we feel that the effort is very worthwhile. The same advantages ultrasound enjoys for other body regions make it a modality that will see increased use in the chest as well. We hope that this monograph will stimulate our colleagues to explore and expand upon the techniques described.

Thoraxsonography--Part I: Chest wall and pleura

The fact that ultrasound (US) waves are reflected completely by the bony thorax and are erased from the aerated lung to a large extent led to the mistaken notion that sonography is not a very useful diagnostic tool for use in this region. On the other hand, since the beginning of US imaging, reports have been published regularly on pleuropulmonary sonographic diagnostic and therapeutic procedures. Rib fractures could be detected about twice as often by US than x-ray. With regard to determining the nodal status in neoplastic disease of the axilla and supraclavicular fossa, US is superior to palpation. In imaging pleural effusions, US is more accurate than chest film and is useful in determining the nature of the pleural effusion. Sonographic evidence of pleural nodules is a specific finding in patients with a malignant effusion. Chest sonography is a useful diagnostic tool for critically ill patients with chest diseases. Performed at the bedside, this technique can be particularly helpful when computed tomography is not available or when critically ill patients cannot be moved.