A lung disease diagnosis algorithm based on 2D spectral features of ultrasound RF signals

Lung diseases are commonly diagnosed based on clinical pathological indications criteria and radiological imaging tools (e.g., X-rays and CT). During a pandemic like COVID-19, the use of ultrasound imaging devices has broadened for emergency examinations by taking their unique advantages such as portability, real-time detection, easy operation and no radiation. This provides a rapid, safe, and cost-effective imaging modality for screening lung diseases. However, the current pulmonary ultrasound diagnosis mainly relies on the subjective assessments of sonographers, which has high requirements for the operator's professional ability and clinical experience. In this study, we proposed an objective and quantifiable algorithm for the diagnosis of lung diseases that utilizes two-dimensional (2D) spectral features of ultrasound radiofrequency (RF) signals. The ultrasound data samples consisted of a set of RF signal frames, which were collected by professional sonographers. In each case, a region of interest of uniform size was delineated along the pleural line. The standard deviation curve of the 2D spatial spectrum was calculated and smoothed. A linear fit was applied to the high-frequency segment of the processed data curve, and the slope of the fitted line was defined as the frequency spectrum standard deviation slope (FSSDS). Based on the current data, the method exhibited a superior diagnostic sensitivity of 98% and an accuracy of 91% for the identification of lung diseases. The area under the curve obtained by the current method exceeded the results obtained that interpreted by professional sonographers, which indicated that the current method could provide strong support for the clinical ultrasound diagnosis of lung diseases.

Interrater reliability in assigning a lung ultrasound score

BACKGROUND AND PURPOSE

Lung ultrasound (LUS) for physiotherapists is an emerging bedside tool. The LUS score of aeration presents as a possible means of assessing and monitoring lung aeration associated with respiratory physiotherapy treatments. There are no studies to date that have assessed the interrater reliability (IRR) of physiotherapists assigning the LUS score of aeration. This study assessed the IRR of assigning the LUS score among adult, mechanically ventilated patients in an intensive care unit with a clinical suspicion of acute lobar atelectasis.

METHODS

A convenience sample of patients had an LUS performed by a physiotherapist, and images were independently reviewed by two physiotherapists. Each lung zone was assigned an LUS score between 0 and 3 (with 0 being normal aeration and 3 being complete consolidation, presence of effusion, or pneumothorax). IRR was assessed using the kappa statistic.

RESULTS

A total of 1032 LUS images were obtained. Assigning of the LUS across all lung zones demonstrated substantial agreement with kappa 0.685 (95% confidence interval: 0.650, 0.720). Right (0.702 [0.653, 0.751]) and left (0.670 [0.619, 0.721]) lung zones also demonstrated substantial agreement.

CONCLUSION

We found substantial IRR between physiotherapists in assigning the LUS score in a mechanically ventilated adult population in the intensive care unit.

AUSTRALIAN NEW ZEALAND CLINICAL TRIALS REGISTRATION NUMBER

ACTRN12619000783123.

B-Line Artifact as a Diagnostic Tool in Various Conditions at the Emergency Department

BACKGROUND: B-line artifacts (BLAs) play an important role in identifying lung pathology. They may indicate different diseases. However, the diagnostic study of BLA as applied to emergency patients has not been well studied. AIM: The aim of this study was to determine the diagnostic accuracy of BLA in various conditions. METHODS: This was a retrospective observational study of emergency patients who had received lung ultrasound at Srinagarind Hospital’s Emergency Department throughout January 2020–December 2020. Ultrasound artifacts were recorded. Ultrasonography findings were correlated with final diagnosis. Sensitivity and specificity were also calculated. RESULTS: A total of 105 patients were evaluated. The most prevalent condition which BLA found in this study was pulmonary edema (44.12%) with 88.24% sensitivity and 46.48% specificity. BLA also indicated pneumonia with 66.67% sensitivity and 35.71% specificity. Diffuse BLA indicated pulmonary edema with 70% sensitivity and 70.42% specificity. Focal BLA indicated pneumonia with 28.57% sensitivity and 76.19% specificity. CONCLUSIONS: The sensitivity of BLA for pulmonary edema and pneumonia diagnosis in this study was of moderate to good sensitivity, but low specificity. BLA may become crucial in the diagnosis of lung pathology in the emergency department.

Lung ultrasound has greater accuracy than conventional respiratory assessment tools for the diagnosis of pleural effusion, lung consolidation and collapse: a systematic review

QUESTION

In mechanically ventilated adults in intensive care, what is the accuracy of lung ultrasound (LUS) for the diagnosis of pleural effusion, lung consolidation and lung collapse when compared with chest radiograph (CXR) and lung auscultation, with computed tomography (CT) as the reference standard?

DESIGN

Systematic review with meta-analysis of prospective cohort studies.

PARTICIPANTS

Adult patients admitted to intensive care, with diagnostic uncertainty at enrolment regarding pleural effusion, lung consolidation and/or collapse/atelectasis.

INDEX TEST

The diagnostic accuracy of LUS as the index test was estimated against CXR and/or lung auscultation as comparators, with thoracic CT scan as the reference standard.

OUTCOME MEASURES

Measures of diagnostic accuracy.

RESULTS

Seven eligible studies were identified, five of which (with 253 participants) were included in the meta-analysis. It was found that LUS had a pooled sensitivity of 92% and 91% in the diagnosis of consolidation and pleural effusion, respectively, and pooled specificity of 92% for both pathologies. CXR had a pooled sensitivity of 53% and 42% and a pooled specificity of 78% and 81% in the diagnosis of consolidation and pleural effusion, respectively. A meta-analysis for lung auscultation was not possible, although a single study reported a sensitivity and specificity of 8% and 100%, respectively, for diagnosing consolidation, and a sensitivity and specificity of 42% and 90%, respectively, for diagnosing pleural effusion.

CONCLUSION

This systematic review with meta-analysis demonstrated high sensitivity of LUS compared with CXR, with similar specificities when diagnosing pleural effusion and lung consolidation/collapse.

REGISTRATION

PROSPERO CRD42018095555.

Parasternal intercostal muscle ultrasound in chronic obstructive pulmonary disease correlates with spirometric severity

In chronic obstructive pulmonary disease (COPD), loss of computed tomography (CT)-measured intercostal mass correlates with spirometric severity. Intercostal muscle ultrasound offers a repeatable and radiation-free alternative, however requires validation. We aimed to determine the reliability of parasternal intercostal muscle ultrasound, and the concurrent validity of parasternal ultrasound with clinicometric parameters. Twenty stable COPD patients underwent ultrasound measurement of thickness and echogenicity of 2^nd and 3^rd parasternal intercostal muscles, dominant pectoralis major and quadriceps, and diaphragm thickness; spirometry; and chest CT. Intra-rater intraclass correlation (ICC) for ultrasound intercostal thickness was 0.87-0.97 depending on site, with echogenicity ICC 0.63-0.91. Inter-rater ICC was fair to excellent. Ultrasound intercostal thickness moderately correlated with FEV₁% predicted (r = 0.33) and quadriceps thickness (r = 0.31). Echogenicity correlated negatively with FEV₁% predicted (r = -0.32). CT-measured lateral intercostal mass correlate negatively with parasternal ultrasound intercostal thickness. These data confirm ultrasound of parasternal intercostal musculature is reproducible. Lower intercostal muscle quantity and quality reflects greater COPD spirometric severity. This novel tool may have biomarker potential for both the systemic effects of COPD on muscle as well as local disruption of respiratory mechanics. The negative correlation between CT and ultrasound measurements may reflect complex site-dependent interactions between respiratory muscles and the chest wall.

Diagnostic chest ultrasound for acute respiratory failure

Acute respiratory failure (ARF) is a common life-threatening medical condition, with multiple underlying aetiologies. Diagnostic chest ultrasound provides accurate diagnosis of conditions that commonly cause ARF, and may improve overall diagnostic accuracy in critical care settings as compared to standard diagnostic approaches. Respiratory physicians are becoming increasingly familiar with ultrasound as a part of routine clinical practice, although the majority of data to date has focused on the emergency and intensive care settings. This review will examine the evidence for the use of diagnostic chest ultrasound, focusing on different levels of imaging efficacy; specifically ultrasound test attributes, impacts on clinician behaviour and impact on health outcomes. The evidence behind use of multi-modality ultrasound examinations in ARF will be reviewed. It is hoped that readers will become familiar with the advantages and potential issues with chest ultrasound, as well as evidence gaps in the field.

A prospective cohort study of thoracic ultrasound in acute respiratory failure: the C3PO protocol

OBJECTIVES

This study was performed to assess the clinical utility of a standardised thoracic ultrasound examination when added to standard care in patients with acute respiratory failure admitted to an intermediate care unit. This study aimed to assess the impact on clinical diagnosis, clinician confidence and management. Ultrasound has been shown to have utility in patients admitted to intensive care and emergency; however, utility in a ward setting is unknown.

DESIGN

Prospective cohort study.

SETTING

Tertiary hospital in Melbourne, Australia.

PARTICIPANTS

50 patients with acute respiratory failure requiring admission to an intermediate care unit.

MAIN OUTCOME MEASURES

(1) Change in clinical diagnosis or additional clinical diagnosis following thoracic ultrasound. (2) Change in diagnostic confidence following thoracic ultrasound. (3) Change to management following thoracic ultrasound.

RESULTS

In 34% of patients, ultrasound detected unexpected findings that changed or added to the clinical diagnosis. Diagnostic confidence was increased in 44%, and the treating clinician altered the management plan in 30% as a result of the ultrasound. Ultrasound was particularly useful in clarifying the diagnosis in patients with multiple initial diagnoses, reducing to a single diagnosis in 69%.

CONCLUSIONS

Thoracic ultrasound has clinical utility in non-intubated adults with acute respiratory failure managed outside intensive care settings. It changed aetiological diagnosis, increases diagnostic confidence and altered clinical management in one out of three patients scanned. Our results suggest extended utility of thoracic ultrasound in acute respiratory failure to a broader context outside the intensive care unit population.

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.

Learner Improvement From a Simulation-Enhanced Ultrasonography Curriculum for First-Year Medical Students

OBJECTIVES

We describe a simulation-enhanced ultrasonography (US) curriculum for first-year medical students as part of a comprehensive curricular integration of US skills. Our goal was to assess student knowledge and performance of US and determine their satisfaction with the integrated curriculum.

METHODS

A committee of basic science, clinical, and interinstitutional faculty developed 7 educational US modules integrated into existing anatomy and physiology courses. First-year students in years 2012 through 2014 were administered a demographic survey and a knowledge-based pretest at the outset of the US program and assessed with a posttest, satisfaction survey, and their image acquisition abilities in an objective structured clinical examination with standardized patients on completion of the program.

RESULTS

Data from 390 students showed a significant increase in knowledge from the pretest to the posttest [t₍₃₈₉₎  = 58.027; P < .0001]. Students with higher spatial abilities or some previous US experience performed better on the posttest. The objective structured clinical examination results showed that about 83% of the students were able to capture acceptable or marginally acceptable images. Ninety-five percent of students indicated that the US educational experience enhanced their medical education.

CONCLUSIONS

Initial results show that we were able to successfully develop, implement, and evaluate performance of first-year medical students on their fundamental knowledge and performance of basic US using a model that emphasized hands-on simulation-enhanced training. Furthermore, most students found the experience to be a beneficial component of their education and indicated a desire for more US training in the medical curricula.

Accuracy and safety of ward based pleural ultrasound in the Australian healthcare system

BACKGROUND AND OBJECTIVE

Ultrasound has been shown to improve the accuracy and safety of pleural procedures. Studies to date have been performed in large, specialized units, where pleural procedures are performed by a small number of highly specialized physicians. There are no studies examining the safety and accuracy of ultrasound in the Australian healthcare system where procedures are performed by junior doctors with a high staff turnover.

METHODS

We performed a retrospective review of the ultrasound database in the Respiratory Department at the Royal Melbourne Hospital to determine accuracy and complications associated pleural procedures.

RESULTS

A total of 357 ultrasounds were performed between October 2010 and June 2013. Accuracy of pleural procedures was 350 of 356 (98.3%). Aspiration of pleural fluid was successful in 121 of 126 (96%) of patients. Two (0.9%) patients required chest tube insertion for management of pneumothorax. There were no recorded pleural infections, haemorrhage or viscera puncture.

CONCLUSION

Ward-based ultrasound for pleural procedures is safe and accurate when performed by appropriately trained and supported junior medical officers. Our findings support this model of pleural service care in the Australian healthcare system.

The diagnostic accuracy of chest ultrasound for CT-detected radiographic consolidation in hospitalised adults with acute respiratory failure: a systematic review

OBJECTIVES

(1) Summarise chest ultrasound accuracy to diagnose radiological consolidation, referenced to chest CT in patients with acute respiratory failure (ARF). (2) Directly compared ultrasound with chest X-ray.

SETTING

Hospitalised patients.

PARTICIPANTS

Studies were eligible if adult participants in respiratory failure underwent chest ultrasound to diagnose consolidation referenced to CT. Exclusion: (1) not primary study, (2) not respiratory failure, (3) not chest ultrasound, (4) not consolidation, (5) translation unobtainable, (6) unable to extract data, (7) unable to obtain paper. 4 studies comprising 224 participants met inclusion.

OUTCOME MEASURES

As planned, paired forest plots display 95% CIs of sensitivity and specificity for ultrasound and chest X-ray. Sensitivity and specificity from each study are plotted in receiver operator characteristics space. Meta-analysis was planned if studies were sufficiently homogeneous and numerous (≥4). Although this numerical requirement was met, meta-analysis was prevented by heterogeneous units of analysis between studies.

RESULTS

All studies were in intensive care, with either a high risk of selection bias or high applicability concerns. Studies had unclear or high risk of bias related to use of ultrasound. Only 1 study clearly performed ultrasound within 24 h of respiratory failure diagnosis. Ultrasound sensitivity ranged from 0.91 (95% CI 0.81 to 0.97) to 1.00 (95% CI 0.95 to 1.00). Specificity ranged from 0.78 (95% CI 0.52 to 0.94) to 1.00 (0.99 to 1.00). In two studies, chest X-ray had lower sensitivity than ultrasound, but there were insufficient patients to compare specificity.

CONCLUSIONS

Four small studies suggest ultrasound is highly sensitive and specific for consolidation in ARF, but high risk of bias and concerns about applicability in all studies may have inflated diagnostic accuracy. Further robustly designed studies are needed to define the role of ultrasound in this setting.

TRIAL REGISTRATION NUMBER

http://www.crd.york.ac.uk/PROSPERO/ (CRD42013006472).

Direct ultrasound localisation for pleural aspiration: translating evidence into action

BACKGROUND

There is strong evidence that direct ultrasound localisation for pleural aspiration reduces complications, but this practice is not universal in Australia and New Zealand.

AIMS

To describe the current utilisation and logistical barriers to the use of direct ultrasound localisation for pleural aspiration by respiratory physicians from Australia and New Zealand, and to determine the cost benefits of procuring equipment and training resources in chest ultrasound.

METHODS

We surveyed all adult respiratory physician members of the Thoracic Society of Australia and New Zealand regarding their use of direct ultrasound localisation for pleural aspiration. We performed a cost-benefit analysis for acquiring bedside ultrasound equipment and estimated the capacity of available ultrasound training.

RESULTS

One hundred and forty-six of 275 respiratory physicians responded (53% response). One-third (33.6%) of respondents do not undertake direct ultrasound localisation. Lack of training/expertise (44.6%) and lack of access to ultrasound equipment (41%) were the most frequently reported barriers to performing direct ultrasound localisation. An average delay of 2 or more days to obtain an ultrasound performed in radiology was reported in 42.7% of respondents. Decision-tree analysis demonstrated that clinician-performed direct ultrasound localisation for pleural aspiration is cost-beneficial, with recovery of initial capital expenditure within 6 months. Ultrasound training infrastructure is already available to up-skill all respiratory physicians within 2 years and is cost-neutral.

CONCLUSION

Many respiratory physicians have not adopted direct ultrasound localisation for pleural aspiration because they lack equipment and expertise. However, purchase of ultrasound equipment is cost-beneficial, and there is already sufficient capacity to deliver accredited ultrasound training through existing services.

Rare pleural tumors

Primary pleural tumors other than mesothelioma account for fewer than 1% of all lung cancers, and consequently they pose diagnostic and management challenges. Their treatment must be targeted toward the specific tumor type and is often quite different from the treatment for mesothelioma or metastases. Despite the best efforts at diagnosing and treating these tumors, the prognosis associated with some of the benign and many of the malignant variants of these tumors remains poor. In this review, we describe the radiologic and pathologic features of the less common primary pleural tumors and propose a diagnostic approach to their evaluation.