Speckle tracking quantification of lung sliding for the diagnosis of pneumothorax: a multicentric observational study
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.
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.
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).
Speckle tracking technology allows lung sliding quantification and detection of lung sliding abolition in case of pneumothorax on selected ultrasound loops.
KeywordsPoint-of-care lung ultrasound Pneumothorax Speckle tracking Lung sliding
Authors warmly thank WINFOCUS-France group for its contribution to this work.
Compliance with ethical standard
Conflicts of interest
XB and LZ declare a competing interest as an ultrasound teacher for GE (GE MEDICAL SYSTEMS ULTRASOUND) customers. ML declares a competing interest with Amomed, Aguettant, MSD, 3 M, Pfizer, Aspen, Orion.
Supplementary material 2 (AVI 7296 kb). Video clip of region of interest positioning for speckle tracking analysis of the lung sliding. The region of interest presents 3 segments (yellow, blue, green)
Supplementary material 3 (AVI 2103 kb). Video clip of multimodal analysis result of speckle tracking applied on lung sliding. Left upper side (a): video clip showing visual pleural lung sliding tracking with region of interest deformation. Right upper side (b): graphic showing curves traducing strain over time of each segment. White squares correspond to maximal longitudinal strain values. The strain values vary during time due to pleural sliding induced by spontaneous breathing. Left bottom side (c): maximal longitudinal pleural strain value of each segment of the region of interest. Right bottom side (d): color diagram presenting variation of strain values over time for each segment (yellow, blue, green) from up to down. Red symbolize negative values of strain, blue symbolize positive values of strain. Absolute value is coded from pale (low) to dark (high). Colors vary over time in term of side and intensity (from pale to dark)
Supplementary material 4 (AVI 996 kb). Video clip of multimodal analysis result of speckle tracking applied on lung sliding abolition. Left upper side (a): video clip showing no visual pleural lung sliding tracking with no region of interest deformation despite spontaneous breathing and thoracic movements. Right upper side (b): graphic showing curves traducing strain over time of each segment. White squares correspond to maximal longitudinal strain values. Curves remain linear despite spontaneous breathing and thoracic movements traducing low strain values. Left downside (c): maximal longitudinal pleural strain value of each segment of the region of interest. The strain values remain low overtime despite spontaneous breathing and thoracic movements. Right bottom side (d): color diagram presenting variation of strain values over time for each segment (yellow, blue, green) from up to down. Red symbolizes negative values of strain, blue symbolizes positive values of strain. Absolute value is coded from pale (low) to dark (high). Colors do not vary and remain in pale tones
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