High-frequency ultrasound (HFU) of the skin can help evaluate the progression and define disease activity in patients with systemic sclerosis (SSc), researchers suggest.
This noninvasive method was seen to have the potential to effectively and quantitatively measure skin thickness, representing an attractive strategy to objectively assess skin changes in patients with SSc.
The findings were reported in the study, “High-frequency ultrasound of the skin in systemic sclerosis: an exploratory study to examine correlation with disease activity and to define the minimally detectable difference.”
Skin tightening is a classic hallmark of SSc and is commonly used to classify subtypes of the disease.
Established in 1979, the modified Rodnan skin score (mRSS) is a validated and widely used tool to evaluate skin thickening in systemic sclerosis. It reflects changes in skin, and it helps predict long-term progression and outcomes in SSc patients.
Still, as the mRSS is based on the assessment of skin thickening by palpation, it is not an objective measure and it can fail to detect small degrees of skin change.
In recent years, the high-frequency ultrasound method has been proposed as an alternative diagnostic tool for SSc.
HFU can assess the different layers of skin — the epidermis, dermis, and subcutaneous layers — and so holds the potential to effectively measure small changes in skin thickness.
Now, in the study published in the journal Arthritis Research & Therapy, researchers in Hebei, China, and UCLA evaluated the potential of high-frequency ultrasound to determine skin involvement and predict disease activity in patients with systemic sclerosis.
The study enrolled 31 SSc patients and 31 age- and sex-matched healthy volunteers. All participants underwent HFU skin evaluation at five sites: the forearm, hand, phalanx, leg, and chest.
Results showed that evaluation of total skin thickness by both HFU and mRSS scores confirmed that SSc patients had significantly thicker skin than the healthy controls.
Interestingly, the team found that HFU measures could recognize increased skin thickness, compared to the controls, in patients who were classified as having a clinically normal skin score (an mRSS score of zero).
The researchers believe these results suggest that “skin involvement happened prior to being able to detect it clinically.”
This potential to recognized SSc skin involvement was also extended to patients who had mRSS scores of 1 and 2 (mild and moderate thickness).
HFU total skin thickness was able to effectively predict 85.71% of SSc cases. In fact, HFU skin values above 7.4 mm were found to be correlated to elevated mRSS and EUSTAR-DAI scores (European Scleroderma Trial and Research group Disease Activity Index), which suggests that “to some extent, skin thickness assessed by ultrasound could reflect disease activity,” the researchers wrote.
“HFU may be able to examine both skin thickness and interstitial edema [tissue swelling], which may mean this modality is able to better examine prognosis and determine drug response [in SSc patients],” the team concluded.