Diffuse interstitial lung disease (PID) is the leading cause of death in systemic scleroderma (SSc). Major progress has recently been made in its therapeutic management. Early diagnosis is essential to optimize this management. Current diagnostic techniques are based on high-resolution computed tomography on the thorax (HRCT) and pulmonary functional tests (PFT). However, these explorations have their limitations. Thus, there is a need for new techniques for a very early diagnosis of PID-SSc.

Thoracic ultrasound (TUS) is an innovative, easily accessible, non-irradiating, inexpensive and painless tool. It is an emerging technique for the diagnosis of PID and has already proven its sensitivity for the detection of interstitial damage, as defined by HRCT.

The main objective of the PRECOSS study is to describe the prevalence of an ultrasound interstitial syndrome in patients with SSc, free of PID-SSc (defined by the Goh criteria) detectable by HRCT.

Inclusion Criteria:

• Age ≥ 18 years old
• Diagnosis of systemic scleroderma according to EULAR/ACR 2013 criteria
• Absence of diffuse interstitial lung disease proven by scanner on the day of inclusion
• Forced vital capacity ≥ 80% of the value predicted on the last respiratory function test performed.
• Carbon monoxide diffusion capacity corrected for hemoglobinemia ≥ 70% of the value predicted on the last respiratory function test performed.
• Patient capable of performing functional exploration during the year
• Affiliation to a social security system
• Patient who has given free and informed consent

Exclusion Criteria:

• Any other connectivity associated to systemic sleroderma
• Any chronic pathologies, co-morbidities, history judged by the investigator as being likely to lead to complications for the patient and/or which may impact the results of functional exploration during exercise.
• All known fibrotic and/or obstructive respiratory pathologies.
• Presence of echocardiographic signs of pulmonary arterial hypertension according to 2015 criteria
• Diagnosis of left heart disease
• Cumulative smoking > 10 packs.years
• Infectious pneumonia within 90 days prior to inclusion
• Acute respiratory illness requiring hospitalization within one year prior to inclusion
• Pregnant or breastfeeding woman
• Refusal to participate in the study
• Refusal to use the data
• Adults under legal protection (temporary protection measure, curatorship, guardianship)