Sono-Elastography: An Ultrasound Quantitative Non-Invasive Measurement to Guide Bacterial Pneumonia Diagnosis in Children

Abstract

Lung ultrasound (LUS) is, at present, a standard technique for the diagnosis of acute lower respiratory tract infections (ALRTI) and other lung pathologies. Its protocolised use has replaced chest radiography and has led to a drastic reduction in radiation exposure in children. Despite its undeniable usefulness, there are situations in which certain quantitative measurements could provide additional data to differentiate the etiology of some pulmonary processes and thus adapt the treatment. Our research group hypothesises that several lung processes such pneumonia may lead to altered lung tissue stiffness, which could be quantified with new diagnostic tests such as lung sono-elastography (SE). An exhaustive review of the literature has been carried out, concluding that the role of SE for the study of pulmonary processes is currently scarce and poorly studied, particularly in pediatrics. The aim of this review is to provide an overview of the technical aspects of SE and to explore its potential usefulness as a non-invasive diagnostic technique for ALRTI in children by implementing an institutional image acquisition protocol.

Keywords: pneumonia; shear wave imaging; sono-elastography; strain imaging; ultrasound.

Figure 1

Ultrasound image corresponding to healthy lung tissue. The different structures and ultrasound artefacts can be seen: ribs (blue) causing a posterior acoustic shadow (yellow), pleural line (red), A-lines (green) and B-lines in normal amount (orange).

Figure 2

(a) BP seen by LUS: lung consolidation (yellow) with branching air bronchograms within it (red). (b) VP seen by LUS: coalescent B-lines (white) with small subpleural consolidations of less than 1 cm (blue), without bronchogram.

Figure 3

Atelectasis seen by LUS: lung consolidation (green) with parallel air bronchograms within it (orange).

Figure 4

SE methods classified by data processing according to strain imaging or shear wave imaging. Figure partially adapted from [29].

Figure 5

SWE applied on a healthy liver. The colour box in the ROI indicates the tissue is predominantly soft (blue), according to the device’s color chart.

Figure 6

Application of SWE to liver tissue. The colour map (left) and the wave propagation map (right) are offered simultaneously while the device records all measurements.

Figure 7

Application of SWE to pulmonary tissue. As in the liver, the colour map (left) and the wave propagation map (right) are offered simultaneously while the device records all measurements.