Usefulness of lung ultrasound B-lines in connective tissue disease-associated interstitial lung disease: a literature review

Abstract

Interstitial lung disease (ILD) is a major pulmonary manifestation of connective tissue disease (CTD), leading to significant morbidity and mortality. Chest high-resolution computed tomography (HRCT) is presently considered the diagnostic gold standard for pulmonary fibrosis diagnosis and quantification in the clinical arena. However, not negligible doses of ionizing radiation limit the use of HRCT, especially for serial follow-up in younger female patients. In the past decade, lung ultrasound (LUS) has been proposed to assess ILD by detecting and quantifying sonographic B-lines. Previous studies demonstrate that B-lines have a good diagnostic accuracy, especially high sensitivity, and correlate well with HRCT findings, suggesting LUS as a novel, non-invasive, and non-ionizing imaging method to be used in patients with CTD-ILD. Although preliminary data are promising, challenges and controversies still remain. For example, the mechanisms of B-line generation are not fully understood; the diagnostic accuracy and performance characteristics of LUS partially depend on the scanning scheme and scoring system used; and up-to-date B-lines cannot discriminate the early cellular inflammation from the chronic fibrotic phase in CTD-ILD. Therefore it is important for clinicians to understand the strengths and limitations of LUS in CTD-ILD patients, to maximize its value.

Possible Role of Chest Ultrasonography for the Evaluation of Peripheral Fibrotic Pulmonary Changes in Patients Affected by Idiopathic Pulmonary Fibrosis—Pilot Case Series

“…On the other hand, weaknesses of this paper compared with previous works [18,23,[32][33][34] are the lack of information about basal posterior areas, usually the more involved and more informative in the case of IPF patients, the lack of data about respiratory function tests [32], and the lack of ultrasound evaluations of the pleural line performed with linear probes.…”

“…An acoustic map of the peripheral lung is already possible based on these considerations. Echographic scans with a pattern of SIS displaying vertical artifacts prevailing on horizontal phenomena and altered pleural line is in fact indicative of important fibrotic alterations in the peripheral parenchyma [22,23]. Moreover, if, in correspondence of a specific landmark, a LUS pattern 1 changes towards a LUS pattern 3 in a subsequent evaluation over time, this could be indicative of a progression of the diseases in that specific point, and guide the timing of HRCT scan re-evaluation.…”

Interstitial Lung Disease in Rheumatoid Arthritis Remains a Challenge for Clinicians

“…Lung ultrasonography findings have a high sensitivity (89%-97%) but varying specificity (50%-97%) compared to HRCT in patients with RA-ILD [52,53]. However, the etiology of the B lines may be difficult to establish in clinical practice, and differentiation between inflammatory and fibrotic changes is not possible using LUS [54].…”

Imaging and serum biomarkers in connective tissue disease–associated interstitial lung diseases: correlation between lung ultrasound B-lines and KL-6 levels

“…B-Lines are a new sonographic hallmark of connective tissue disease–associated interstitial lung diseases (CTD-ILDs). Promising data have shown that B-lines are associated with high-resolution CT (HRCT), pulmonary function test and some clinical variables, expanding the armamentarium for screening of ILDs 1. Krebs von den Lungen-6 (KL-6) antigen is a mucin-like, high molecular weight glycoprotein expressed on the surface membrane of alveolar epithelial cells Ⅱ and bronchiolar epithelial cells, and increases following cellular injury and/or regeneration 2.…”