Lesions in the lungs caused by ANCA-associated vasculitis (AAV) are variable among patients, but lung ultrasound appears to be as good as computed tomography (CT) scans at detecting them, a study found.
The study, “Utility of lung ultrasound in ANCA-associated vasculitis with lung involvement,” was published in the journal Plos One.
AAV most commonly affects the respiratory tract and kidneys. In fact, vasculitis (inflammation of small blood vessels) involving the airways of the lung is a common characteristic of AAV, affecting up to 90% of patients, and can predate the diagnosis by years.
However, many patients with lesions in the lung don’t present with any respiratory symptoms, and doctors frequently utilize imaging technologies to look for presence of lesions in the lungs.
“In as many as 30% of patients without clinical symptoms of lower respiratory tract involvement, abnormalities in chest imaging examinations can be found,” investigators said.
CT scans are commonly used to detect lesions in patients with AAV, but the need for repeat examinations exposes patients to cumulative doses of radiation. Limiting this exposure is especially important in AAV patients, who are twice as likely to develop cancer.
Lung ultrasound is a safe, portable, and inexpensive diagnostic approach that not only reduces this exposure but is also available in remote areas with limited access to CT scans. Its use is well- documented in many pulmonary diseases, such as pneumonia; however, only a few studies have investigated this methodology in other, less common diseases, such as AAV.
Therefore, researchers in Poland conducted a study to assess lesions detected by lung ultrasound in patients with AAV and compare them to abnormalities found by CT scans.
They examined clinical and imaging data from 38 patients — including 31 with granulomatosis with polyangiitis (GPA) and seven with microscopic polyangiitis (MPA) — diagnosed between January 2013 and October 2017. The patients’ median age was 52 years.
Researchers detected lung involvement in 29 patients, with the most common symptoms including shortness of breath, cough, and coughing up blood.
Lung ultrasound and chest CT scans were conducted in 21 patients, either with active disease or in remission. Some patients had repeated examinations.
According to ultrasound results, there were 17 patients with lung nodules (growth of abnormal tissue) and infiltrates with and without features of disintegration (immune cells that infiltrate the lung, some of which disintegrate).
Three patients experienced diffuse alveolar hemorrhage (bleeding in small vessels of the lung), and 11 patients had features of interstitial lung disease (ILD) with pulmonary fibrosis (scarring of the lungs).
Results from CT scans, on the other hand, showed that 12 patients had infiltrations with features of disintegration, eight patients had lesions typical of ILD and two patients had diffuse alveolar hemorrhage.
In two other patients, both ultrasound and CT scans were negative for lung lesions; in four cases, ultrasound was negative, despite a positive CT result.
“Both in CT and [lung ultrasound], images of pulmonary lesions were consistent though highly variable,” researchers concluded, adding that further studies on larger patient populations are needed “to assess the sensitivity and specificity of [lung ultrasound] in relation to chest CT.”