Ultrasound artifacts mimicking pleural sliding after pneumonectomy

Influence of intercostal muscles contraction on sonographic evaluation of lung sliding: a physiological study on healthy subjects

OBJECTIVES

To investigate the following: (a) effects of intercostal muscle contraction on sonographic assessment of lung sliding and (b) inter-rater and intra-observer agreement on sonographic detection of lung sliding and lung pulse.

METHODS

We used Valsalva and Muller maneuvers as experimental models in which closed glottis and clipped nose prevent air from entering the lungs, despite sustained intercostal muscles contraction. Twenty-one healthy volunteers underwent bilateral lung ultrasound during tidal breathing, apnea, hyperventilation, and Muller and Valsalva maneuvers. The same expert recorded 420 B-mode clips and 420 M-mode images, independently evaluated for the presence or absence of lung sliding and lung pulse by three raters unaware of the respiratory activity corresponding to each imaging.

RESULTS

During Muller and Valsalva maneuvers, lung sliding was certainly recognized in up to 73.0% and up to 68.7% of imaging, respectively, with a slight to fair inter-rater agreement for Muller maneuver and slight to moderate for Valsalva. Lung sliding was unrecognized in up to 42.0% of tidal breathing imaging, and up to 12.5% of hyperventilation imaging, with a slight to fair inter-rater agreement for both. During apnea, interpretation errors for sliding were irrelevant and inter-rater agreement moderate to perfect. Even if intra-observer agreement varied among raters and throughout respiratory patterns, we found it to be higher than inter-rater reliability.

CONCLUSIONS

Intercostal muscles contraction produces sonographic artifacts that may simulate lung sliding. Clinical studies are needed to confirm this hypothesis. We found slight to moderate inter-rater agreement and globally moderate to almost perfect intra-observer agreement for lung sliding and lung pulse.

TRIAL REGISTRATION

ClinicalTrials.gov registration number. NCT02386696.

Lung, Pleura, and Diaphragm Point-of-Care Ultrasound

Thoracic Ultrasonography involves the ultrasonographic examination of the lungs, pleura, and diaphragm. This provides a plethora of clinical information during the point of care assessment of patients. The air filled lungs create consistent artifacts and careful examination and understanding of these artefactual signs can provide useful information on underlying clinicopathologic states. This review aims to provide a review of the ultrasound signs and features that can be seen in horacic ultrasonography and summarize the clinical evidence to support its use.

The artificial count of artifacts for thoracic ultrasound: what is the clinical usefulness?

Many works in the literature have shown that the increase in the number of B lines is a nonspecific sign of underlying pulmonary disease. Actually these artifacts are the result of a physical effect of ultrasound between the chest wall and the pulmonary air. Nevertheless the intra- and inter-operator variability in B-lines counting does not only reside only in the count itself but depends also on the type and frequency of the probe used, as well as the ultrasound scan machine setting and the patient's chest shape. In our opinion, proposing a software algorithm to count lines B seems like an unproductive effort.

Transthoracic ultrasound sign in severe asthmatic patients: a lack of "gliding sign" mimic pneumothorax

Transthoracic ultrasound (TUS) is a validate complementary technique widely used in everyday medical practice. TUS is the gold-standard for studying pleural effusion and for echo-guided thoracentesis, moreover, it is employed in detection of pleural and pulmonary lesions adherent to pleural surface and their ccho-guided percutaneous needle biopsy (PTNB).¹ We used TUS technique to study severe asthma patients. We found that several patterns are constant in these patients. One of these patterns, i.e. lack of gliding sign, mimic pneumothorax (PNX). In this study, we attempted an echographic approach to asthma, trying to lay the first stone for the individuation of common ultrasound patterns in this disease.

Ultrasound and interstitial lung disease: use and limitations

The Connective Tissue Diseases (CTDs)-related Interstitial Lung Disease (ILD) early diagnosis by Transthoracic Ultrasound (TUS) still arises several issues. Gutierrez et al. clearly underlined the current role of ultrasound artifacts for ILD definition according to some Authors. In this Letter to the Editor, we would like to highlight the proper role of TUS and its pitfalls.

Speckle tracking quantification of lung sliding for the diagnosis of pneumothorax: a multicentric observational study

PURPOSE

Lung ultrasound is used for the diagnosis of pneumothorax, based on lung sliding abolition which is a qualitative and operator-dependent assessment. Speckle tracking allows the quantification of structure deformation over time by analysing acoustic markers. We aimed to test the ability of speckle tracking technology to quantify lung sliding in a selected cohort of patients and to observe how the technology may help the process of pneumothorax diagnosis.

METHODS

We performed retrospectively a pleural speckle tracking analysis on ultrasound loops from patients with pneumothorax. We compared the values measured by two observers from pneumothorax side with contralateral normal lung side. The receiver operating characteristic (ROC) curve was constructed to evaluate the performance of maximal pleural strain to detect the lung sliding abolition. Diagnosis performance and time to diagnosis between B-Mode and speckle tracking technology were compared from a third blinded observer.

RESULTS

We analysed 104 ultrasound loops from 52 patients. The area under the ROC curve of the maximal pleural strain value to identify lung sliding abolition was 1.00 [95%CI 1.00; 1.00]. Specificity was 100% [95%CI 93%; 100%] and sensitivity was 100% [95%CI 93%; 100%] with the best cut-off of 4%. Over 104 ultrasound loops, the blinded observer made two errors with B-Mode and none with speckle tracking. The median diagnosis time was 3 [2-5] seconds for B-Mode versus 2 [1-2] seconds for speckle tracking (p = 0.001).

CONCLUSION

Speckle tracking technology allows lung sliding quantification and detection of lung sliding abolition in case of pneumothorax on selected ultrasound loops.

Video-assisted thoracic surgery ultrasound (VATS-US) in the evaluation of subpleural disease: preliminary report of a systematic study

We provide a pictorial essay examining the preliminary data of an ongoing study whose primary aim is to assess the usefulness and safety of video-assisted thoracic surgery ultrasound (VATS-US) in the identification of different lung diseases. We studied 14 patients (five women and nine men with a mean age of 56.2 ± 8.4 SD years) with indication for VATS. All patients underwent pre-operative imaging of the chest using high-resolution computed-tomography, contrast-enhanced computed-tomography, and/or positron emission tomography and transthoracic ultrasound. VATS-US was performed under general anesthesia with single-lung ventilation through double-lumen endotracheal intubation in all patients, and the Esaote MyLab 25 laparoscope probe with flexible tip and a linear array transducer at frequencies 8.0-12.0 MHz was used. The final histological diagnoses in our cohort were cancer (three cases), usual interstitial pneumonia (five cases), nonspecific interstitial pneumonia (two cases), and hypersensitivity pneumonitis (one case). In patients with pulmonary fibrosis, the VATS-US showed a thick hyperechoic pleural line and no B-lines. Regarding cancer nodules, the VATS-US images showed a uniform hypoechogenic pattern with jagged margins. In patients with hamartochondroma and histocytosis X, VATS-US showed a mixed hyperechoic structure of the margins. In conclusion, we described the US semeiotics of various lung disorders assessed during VATS by reporting the preliminary data of the first study which applies the methodology systematically to all patients undergoing the surgery procedure. Final results from the study will further elucidate how the technique could be of use during the VATS procedure.