Specialized MRI scans may catch early lung damage in scleroderma
Study: They're effective even when standard tests show only mild disease
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A specialized MRI technique may help detect early lung abnormalities in people with systemic sclerosis (SSc), even when standard tests show only mild lung disease, a new U.S. study suggests.
Using Xenon MRI, or Xe-MRI, which tracks how gases move through the lungs, researchers found that women with SSc showed abnormalities in measurements related to how gases move from the lung into red blood cells. According to researchers, these findings may indicate early damage to the lungs’ blood vessels.
These findings suggest that “Xe-MRI is a promising technique for identifying subclinical vascular impairment in SSc lung disease,” researchers wrote.
The study, “Characterization of Pulmonary Functional Abnormalities in Systemic Sclerosis Using Xenon MRI,” was published in the Journal of Magnetic Resonance Imaging.
Xe-MRI increasingly used to evaluate lung disease in ILD, PH patients
SSc, also known as scleroderma, occurs when the immune system mistakenly attacks healthy tissues, leading to inflammation, blood vessel damage, and excess scar tissue buildup in the skin and internal organs. When the lungs are affected, this can lead to interstitial lung disease (ILD), in which the lung tissue becomes scarred and stiff, or to pulmonary hypertension (PH), in which the blood pressure in the lung’s blood vessels becomes abnormally high.
Current approaches for assessing abnormalities in lung structure and function in SSc, including CT scans and pulmonary function tests, can detect advanced disease but are less effective at identifying early functional abnormalities or determining whether damage stems primarily from the lung tissue or blood vessels.
“As a result, there remains a critical unmet need for non-invasive imaging biomarkers capable of detecting early pulmonary dysfunction and monitoring the development of disease in these patients,” the researchers wrote.
Xe-MRI is an emerging imaging technique increasingly used to evaluate lung disease in people with ILD and PH. During the scan, patients inhale hyperpolarized xenon-129 gas, a form of xenon gas that can be tracked on MRI scans, and hold their breath briefly while images are taken. The technique generates three-dimensional images showing airflow and gas exchange in the lungs.
“As such, Xe-MRI may be suited to interrogate lung function impairment in SSc,” the researchers wrote.
Imaging technique revealed clear abnormalities in gas exchange
To better understand how Xe-MRI findings appear in people with SSc and how these measurements compare with standard measures of lung structure and function, a team of researchers in the U.S. conducted a prospective study involving 18 women with SSc and 13 healthy women, along with three men in each group. Because few men were enrolled, their data were presented descriptively but excluded from the main analyses.
Age, body mass index (a measure of body fat based on height and weight), and smoking status were similar between the two groups. Still, participants with SSc had significantly lower forced vital capacity (FVC) values than healthy volunteers. FVC measures the maximum amount of air a person can forcibly exhale after taking a deep breath and is commonly used to assess lung function.
Among people with SSc, half had interstitial abnormalities visible on CT scans, while the other half had normal CT findings. Similarly, about half had reduced FVC values and about half had reduced diffusing capacity for carbon monoxide (DLCO), a measure of how effectively gases move from the lungs into the bloodstream. Five participants had CT evidence of PH, and five had a clinical diagnosis of PH.
Follow-up pulmonary function tests performed one year after MRI showed only small average changes in FVC and DLCO measurements, suggesting that lung disease remained generally stable during that period, the researchers noted.
These findings support that SSc lung disease has a primarily vascular origin and suggest Xe-MRI is a promising technique for identifying subclinical vascular impairment in SSc lung disease.
Despite a mild, stable disease profile, Xe-MRI revealed clear abnormalities in gas exchange. Compared with healthy volunteers, women with SSc had significantly lower red blood cell (RBC) transfer and RBC/membrane ratio, suggesting gases moved less efficiently from the lungs into the blood. They also had significantly higher RBC defect percentages, indicating larger regions of impaired gas exchange within the lungs.
According to the researchers, reduced RBC transfer may indicate damage to the lungs’ blood vessels, which is thought to play an important role in SSc-associated lung disease.
By contrast, membrane uptake — a measure of how gas moves into lung tissue and is often elevated in people with ILD — did not differ significantly between women with SSc and healthy women. This pattern suggests that vascular impairment, rather than extensive lung scarring, may play a key role in early SSc-associated lung disease, the researchers noted.
Further supporting this idea, the researchers found that RBC-related Xe-MRI abnormalities were associated with changes in the FVC/DLCO ratio, a measure often used to identify blood vessel-related lung involvement.
In a smaller subgroup of six participants whose CT scans were suitable for detailed blood vessels analysis, reduced RBC transfer on Xe-MRI was strongly associated with changes in small and large blood vessel volumes. However, the researchers cautioned that the sample size was too small to draw firm conclusions.
“These findings support that SSc lung disease has a primarily vascular origin and suggest Xe-MRI is a promising technique for identifying subclinical vascular impairment in SSc lung disease,” the researchers wrote.
