Agreement between chest ultrasonography and chest X-ray in patients who have undergone thoracic surgery: preliminary results

Lung Ultrasound Signs: The Beginning. Part 3-An Accademia di Ecografia Toracica Comprehensive Review on Ultrasonographic Signs and Real Needs

Over the last 20 years, scientific literature and interest on chest/lung ultrasound (LUS) have exponentially increased. Interpreting mixed-anatomical and artifactual-pictures determined the need of a proposal of a new nomenclature of artifacts and signs to simplify learning, spread, and implementation of this technique. The aim of this review is to collect and analyze different signs and artifacts reported in the history of chest ultrasound regarding normal lung, pleural pathologies, and lung consolidations. By reviewing the possible physical and anatomical interpretation of these artifacts and signs reported in the literature, this work aims to present the AdET (Accademia di Ecografia Toracica) proposal of nomenclature and to bring order between published studies.

Chest X-rays and Lung Ultrasound Are Not Interchangeable in Intensive Care Practice

PURPOSE

Data comparing lung ultrasound (LUS) and chest X-rays (CXRs) have increased over the past years. However, there still is a lack of knowledge as to how these modalities compare with one another in the critical care setting, and several factors, including artificial study conditions, limit the generalizability of most published studies. Our study aimed to analyze the performance of LUS in comparison with CXRs in real-world critical care practice.

MATERIALS AND METHODS

This study presents new data from the prospective FASP-ICU trial. A total of 209 corresponding datasets of LUS and CXR results from 111 consecutive surgical ICU patients were subanalyzed, and categorial findings were compared. Statistical analysis was performed on the rates of agreement between the different imaging modalities.

RESULTS

A total of 1162 lung abnormalities were detected by LUS in ICU patients compared with 1228 detected by CXR, a non-significant difference (p = 0.276; 95% CI -0.886 to 0.254). However, the agreement rates varied between the observed abnormalities: the rate of agreement for the presence of interstitial syndrome ranged from 0 to 15%, consolidation from 0 to 56%, basal atelectasis from 33.9 to 49.34%, pleural effusion from 40.65 to 50%, and compression atelectasis from 14.29 to 19.3%. The rate of agreement was 0% for pneumothorax and 20.95% for hypervolemia.

CONCLUSIONS

LUS does not detect more lung abnormalities in real-world critical care practice than CXRs, although a higher sensitivity of LUS has been reported in previous studies. Overall, low agreement rates between LUS and CXRs suggest that these diagnostic techniques are not equivalent but instead are complementary and should be used alongside each other.

Lung Ultrasound Reduces Chest X-rays in Postoperative Care after Thoracic Surgery: Is There a Role for Artificial Intelligence?-Systematic Review

BACKGROUND

Chest X-ray (CXR) remains the standard imaging modality in postoperative care after non-cardiac thoracic surgery. Lung ultrasound (LUS) showed promising results in CXR reduction. The aim of this review was to identify areas where the evaluation of LUS videos by artificial intelligence could improve the implementation of LUS in thoracic surgery.

METHODS

A literature review of the replacement of the CXR by LUS after thoracic surgery and the evaluation of LUS videos by artificial intelligence after thoracic surgery was conducted in Medline.

RESULTS

Here, eight out of 10 reviewed studies evaluating LUS in CXR reduction showed that LUS can reduce CXR without a negative impact on patient outcome after thoracic surgery. No studies on the evaluation of LUS signs by artificial intelligence after thoracic surgery were found.

CONCLUSION

LUS can reduce CXR after thoracic surgery. We presume that artificial intelligence could help increase the LUS accuracy, objectify the LUS findings, shorten the learning curve, and decrease the number of inconclusive results. To confirm this assumption, clinical trials are necessary. This research is funded by the Slovak Research and Development Agency, grant number APVV 20-0232.

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.

State of the Art in Lung Ultrasound, Shifting from Qualitative to Quantitative Analyses

Lung ultrasound (LUS) has been increasingly expanding since the 1990s, when the clinical relevance of vertical artifacts was first reported. However, the massive spread of LUS is only recent and is associated with the coronavirus disease 2019 (COVID-19) pandemic, during which semi-quantitative computer-aided techniques were proposed to automatically classify LUS data. In this review, we discuss the state of the art in LUS, from semi-quantitative image analysis approaches to quantitative techniques involving the analysis of radiofrequency data. We also discuss recent in vitro and in silico studies, as well as research on LUS safety. Finally, conclusions are drawn highlighting the potential future of LUS.

Sensitivity of chest ultrasound for postoperative pneumothorax in comparison to chest X-ray after lung resecting surgery

OBJECTIVES

Thoracic ultrasound is superior to chest X-ray for the detection of a pneumothorax in trauma and intensive care medicine. Data regarding its use in non-cardiac thoracic surgery are scarce and contradictory. Previous studies are heterogeneous regarding sonographic methodology and patient selection. This study aimed to evaluate the accuracy of thoracic ultrasound for pneumothorax assessment after lung resecting surgery in unselected patients.

METHODS

SONOR (SONOgraphy vs x-Ray) is a prospective observational trial (registry-ID DRKS00014557). A total of 123 consecutive patients with lung resecting surgery received a standardized thoracic ultrasound the same day and in addition to routine chest X-rays in erect position after removal of the chest tube. The sonographer was blinded to radiological findings and vice versa.

RESULTS

Sensitivity, specificity, positive and negative predictive values of ultrasound after removing the chest tube were 0.32, 0.85, 0.54, 0.69 for any pneumothorax and 1.0, 0.82, 0.19, 1.0 for pneumothorax ≥3 cm. No clinically relevant pneumothorax was missed. The agreement between sonography- and routine-based therapeutic decisions was 97%. Lung pulse was the most frequently detected sign to sonographically rule out a pneumothorax.

CONCLUSIONS

Postoperative thoracic ultrasound in unselected patients has a low overall sensitivity to detect a residual pneumothorax; however, its sensitivity and negative predictive values regarding clinically relevant pneumothorax are high. Test quality depends on the distinct sonographic methodology and patient selection. Anatomic differences in postsurgical and medical patients may be responsible for the contradictory results of previous trials. Studies with a larger population size are required to validate the accuracy of relevant pneumothoraces and identify appropriate selection criteria.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS-German Clinical Trials Register, www.drks.de, registry-ID DRKS00014557.

Most patient conditions do not a priori debilitate the sensitivity of thoracic ultrasound in thoracic surgery-a prospective comparative study

Background

The few existing studies on the accuracy of lung ultrasound in the detection of a postoperative pneumothorax after thoracic surgery differ in the sonographic technique and the inclusion criteria. Several conditions are considered unfavourable in the sonographic examination of the lung. We aim to test these conditions for their impact on the diagnostic accuracy of lung ultrasound.

Methods

We compared lung ultrasound and chest roentgenograms for the detection of a pneumothorax after lung-resecting surgery in two prospective trials (register ID DRKS00014557 and DRKS00020216). The ultrasound examiners and radiologists were blinded towards the corresponding findings. We performed posthoc subgroup analyses to determine the influence of various patient or surgery related conditions on the sensitivity and specificity of ultrasound in the detection of pneumothorax.

Results

We performed 340 examinations in 208 patients. The covariates were age, gender, body mass index, smoking status, severity of chronic obstructive pulmonary disease, previous ipsilateral operation or irradiation, thoracotomy, postoperative skin emphysema, indwelling chest tube and X-ray in supine position. In univariate analysis, an indwelling chest-tube was associated with a higher sensitivity (58%, p = 0.04), and a postoperative subcutaneous emphysema with a lower specificity (73% vs. 88%, p = 0.02). None of the other subgroups differed in sensitivity or specificity from the total population .

Conclusions

Most of the patient- or surgery related conditions usually considered unfavourable for lung ultrasound did not impair the sensitivity or specificity of lung ultrasound. Further studies should not excluce patients with these conditions, but test the accuracy under routine conditions.

Trial registration

DRKS, DRKS00014557, registered 06/09/2018, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00014557 and DRKS00020216, registered 03/12/2019, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00020216

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01454-6.

Chest Ultrasound Can Reduce the Use of Roentgenograms in Postoperative Care After Thoracic Surgery

BACKGROUND

Roentgenography remains the standard imaging modality after thoracic surgery. Trials from intensive medicine proved a high accuracy of ultrasound examination in the diagnosis of various conditions. The assumption was that ultrasound examination could reduce the number of roentgenograms after thoracic surgery.

METHODS

This prospective study compared ultrasound examinations performed by thoracic surgeons with roentgenograms in the diagnosis of pneumothorax and pleural effusion after noncardiac thoracic surgery. Patients received 2 ultrasound scans, the first on the day of surgery and the second before chest tube removal.

RESULTS

A total of 297 patients underwent 545 examinations; 336 ultrasound scans (61.6%) showed neither pneumothorax nor pleural effusion. Pneumothorax was detected on 69 roentgenograms and 51 ultrasound scans. Both modalities showed positive results in 32 cases and negative results in 395 cases (Cohen's κ, 53.4%). Ultrasound missed 37 clinically irrelevant pneumothoraces. Roentgenograms missed 19 pneumothoraces; 15 of them were clinically irrelevant. Sensitivity and specificity were 59.4% and 95.9% in the first examination and 50.0% and 94.8% in the second examination, respectively. Pleural effusion was detected on 169 roentgenograms and 117 ultrasound scans. Both modalities showed positive results in 88 cases and negative results in 336 cases (Cohen's κ, 49.6%). Ultrasound scans missed 81 pleural effusions; except for 5 cases, the clinical decisions would not have changed. Roentgenograms missed 29 clinically irrelevant pleural effusions. Sensitivity and specificity were 44.4% and 92.6% in the first examination and 60.9% and 91.3% in the second examination, respectively.

CONCLUSIONS

Given high specificities, a large share of results without pneumothorax and pleural effusion, and mismatch analysis, we could reduce the number of roentgenograms by 61.6% by using ultrasound as a primary imaging modality.

The role of point of care ultrasound in radiology department: update and prospective. A statement of Italian college ultrasound

Ultrasound, in its new point-of-care conception, has been called the stethoscope of the future. Goal-directed bedside ultrasound examination, performed by a healthcare provider to answer a specific diagnostic question or guide an invasive procedure, is currently revolutionizing medical practice. It is used by various specialties in multiple clinical contexts for procedural, diagnostic, and screening applications. Point-of-care ultrasound is also a strategic technique in clinical radiology; it brings the radiologist closer to the patient (in interaction and understanding) like interventional and angiography procedures and, as an integrative imaging modality, is a vital radiological tool for decision-making in many situations. In this commentary, we present our observations on the use of ultrasound, in a sincere appeal to refrain from omitting ultrasound as a diagnostic technique in this era of deep professional change, in which radiologists must return to being a true clinical semiologist.

Sensitivity of lung ultrasound for the detection of pneumothorax one day after pulmonary resection—a prospective observational study

Background

Chest X‑ray (CXR) after thoracic surgery contributes to patient discomfort and costs and is of limited therapeutic value. Lung ultrasound (LU) for pneumothorax may be an alternative to CXR, but diagnostic accuracy data are heterogeneous and biased by insufficient sonographic technique and patient selection. Reported sensitivities range from 0.21 to 1.0. We evaluated the sensitivity of LU on the first day after thoracic surgery under routine conditions.

Methods

We performed a prospective observational study (trial-ID DRKS00014557). Consecutive patients undergoing lung resection received standardized LU in addition to routine CXR on the first postoperative day. Ultrasound examiner and radiologist were blinded to corresponding X‑ray and ultrasound findings. CXR was used as reference to determine diagnostic test performance of ultrasound. The conformity of sonography- and routine-based therapeutic decisions was evaluated.

Results

A total of 68 patients were examined. The mean duration of ultrasound was 145 ± 64 s. CXR identified 23 patients with pneumothorax with a mean apex-to-cupola size of 1.5 ± 1.0 cm. Ultrasound detected 18 patients with pneumothorax. The computed sensitivity of LU was 0.48 (95% confidence interval [0.36; 0.60]). Specificity was between 0.81 and 1.0, the negative predictive value 0.76 [0.66; 0.86]. The sensitivity of CXR was 0.56 [0.44; 0.68]. Air leakage via chest tube correlated weakly with CXR (spearman’s rho = 0.26) and moderately with LU (rho = 0.43). The conformity between sonographically based recommendations and the actual therapy based on routine diagnostics was 96%.

Conclusions

Sensitivity of ultrasound for pneumothorax detection nearly reached CXR and resulted in equally safe patient management. Our data can serve as a pilot study for upcoming larger-scaled controlled trials.

Artifactual Lung Ultrasonography: It Is a Matter of Traps, Order, and Disorder

When inspecting the lung with standard ultrasound B-mode imaging, numerous artifacts can be visualized. These artifacts are useful to recognize and evaluate several pathological conditions in Emergency and Intensive Care Medicine. More recently, the interest of the Pulmonologists has turned to the echographic study of the interstitial pathology of the lung. In fact, all lung pathologies which increase the density of the tissue, and do not consolidate the organ, are characterized by the presence of ultrasound artifacts. Many studies of the past have only assessed the number of vertical artifacts (generally known as B-Lines) as a sign of disease severity. However, recent observations suggest that the appearance of the individual artifacts, their variability, and their internal structure, may play a role for a non-invasive characterization of the surface of the lungs, directing the diagnoses and identifying groups of diseases. In this review, we discuss the meaning of lung ultrasound artifacts, and introduce hypothesis on the correlation between their presence and the structural variation of the sub-pleural tissue in light of current knowledge of the acoustic properties of the pleural plane.