Ultrasonographic Presentation and Anatomic Distribution of Lung Involvement in Patients with Rheumatoid Arthritis

Abstract

Background: Rheumatoid arthritis (RA) is a chronic auto-immune disease, typically affecting the joints, which can also present with lung involvement (pleuritis, interstitial lung disease, pulmonary nodules, etc.). Lung ultrasound (LUS) is an upcoming tool in the detection of these pulmonary manifestations.

Methods: We performed a 72-window LUS in 75 patients presenting to the outpatient rheumatology clinic and describe the abnormalities (presence of B-lines (vertical comet-tail artefacts), pleural abnormalities, pleural effusions, and subpleural nodules) on lung ultrasound. We created a topological mapping of the number of B-lines per intercostal zone.

Results: We observed pleural effusions, pleural abnormalities, and pleural nodules in, respectively, 1.3%, 45.3%, and 14% of patients. There were 35 (46.7%) patients who had less than 5 B-lines, 15 (20%) patients who had between 5 and 10 B-lines, 11 (14.6%) between 10 and 20, 10 (13.3%) between 20 and 50, 1 (1.3%) between 50 and 100, and 3 (4%) of patients who had more than 100 B-lines.

Conclusions: LUS in patients with RA shows an array of abnormalities ranging from interstitial syndromes to pleural abnormalities, subpleural nodules, and pleural effusions. Hotspots for the presence of B-lines are situated bilaterally in the posterior subscapular regions, as well as the anterior right mid-clavicular region.

Keywords: extra-articular manifestations of rheumatoid arthritis; lung ultrasound; rheumatoid-arthritis-associated interstitial lung disease.

Figure 1

Bar chart showing the number of patients per number of B-lines, categorized.

Figure 2

Abnormal sonographic findings from 4 patients with RA. (A) LUS image showing 2 B-lines. (B) LUS image showing pleural interruptions and a subpleural nodule. (C) LUS image showing pleural line thickening and 1 B-line. (D) LUS image showing a large pleural effusion with atelectasis of the right lower lobe with multiple inlying B-lines.

Figure 3

Heatmaps. (A) Anatomical (72-zone) heatmap based on the cumulative absolute number of B-lines (50 patients). (B) Schematic (72-zone) heatmap based on the cumulative absolute number of B-lines (50 patients). Every rectangle corresponds to one intercostal space localization. (C) Anatomical (72-zone) heatmap based on the number of patients that scored positive (>1 B-line) per intercostal space (50 patients). (D) Schematic (72-zone) heatmap based on the number of patients that scored positive (>1 B-line) per intercostal space (50 patients). Every rectangle corresponds to one intercostal space localization.