SONOGRAPHIC ASSESSMENT OF INTERSTITIAL LUNG DISEASE IN SYSTEMIC SCLEROSIS PATIENTS

Background: Systemic sclerosis (SSc) is a connective tissue disease characterized by fibrosis of the tissue and organs (skin, heart, lungs, kidneys, and gastrointestinal tract). The most common manifestation of lung involvement is interstitial lung disease (ILD) which determine a negative prognosis. ILD is clinically significant in about 40 of patient with SSc 1 and it did not correlate with the cutaneous manifestations. For the high prevalence and on the prognostic value of ILD diagnosis, it is very important to identify and treat this form of lung involvement as soon as possible. However how to diagnose it in the early phase (where ILD is frequently pauci-symptomatic) is still under debate. HRCT is considered the gold standard in the assessment of ILD but it provide a high rate of radiations. More recently, ultrasound (US) has been used to investigate the lung and a specific finding has been recognized, the so–called US lung comets or B-line (ULCs), when interlobular septa are thickened (both for fibrosis or water) 2. They are defined as an echogenic, coherent, wedge-shaped signal with a narrow origin in the near field of the image 2. Objectives: To assess the validity of US lung examination in a greater population of SSc patients. Methods: Fifty-five in- or out-patients with SSc (according to ACR classification criteria), referring to the Rheumatology Unit of the University of Pisa, were enrolled in the study. Mean age was 52±8.9 years (F:M5:50). All the patients underwent to HRCT and US of the lungs, with both of the exams performed within a week by two independent and blind operators. Chest sonography was performed with a Toshiba Powervision 6000 machine, with a 6-12 MHz linear probe (used at 6 MHz). The scanning protocol was the same as previously reported 3. The sum of the number of ULCs from each intercostals space provide the total score of the US examination. HRCT examinations were performed on a spiral CT/I Highspeed GEMs (General Electrics Medical Systems) scanner and pulmonary involvement was evaluated using the Warrick's score. Results: ULCs were present in 40 out 55 patients, with a men number of ULCs of 5,3. ICC between US and HRCT was good (0.651) and the Jouden test indicate two different set of sensibility and specificity as the best, on the base of different ULCs cut-off used to discriminate between normal and pathologic subjects (84 and 61 respectively for ULCs>9 or 78 and 76 respectively for ULCs>12). Conclusions: ULCs, are often visualized in SSc and good correlation between the presence of ULCs and HRCT results have been demonstrated. US (a safe radiation-free imaging technique widely diffuse among the rheumatologists who could follow SSc patients more strictly) should not be considered as the gold standard for ILD examination in SSc patients. Nevertheless, we suggest that the usual follow-up could be performed routinely using US so, determining a decrease in the total radiation dose in the single patient, and a reduction in the costs related to the management of this disease.