New method of Determination of Orbital Inflammation Activity in GPA

Relevance Orbital involvement is typical in granulomatosis with polyangiitis (GPA) [1–5]. Determining the activity of the inflammatory process in the orbit is key to planning treatment, the purpose of which is to maintain long-term remission. Objective To study the capabilities of ultrasound in determining the stage of orbital inflammation in patients with GPA. Material and methods The study included 24 patients with diffuse orbital involvement in GPA. Among them, there were 8 men (33.3%) and 16 women (66.7%). Local disease was observed in 58.3% (14/24) of patients, and systemic disease in 41.7% (10/24). Group 1 (active stage) included 9 patients, and Group 2 (inactive stage) included 18 patients. Results When conducting an ultrasound examination in the 1st group, we identified color maps of vascular flows in the pathological focus with an active process. When constructing two-dimensional histograms in the 1st group, low acoustic density was detected, on average in the group it was 54 ± 13.1 CU. In 4 patients, the vascularization index was assessed, its value was on average 9.2%. In the 2nd group, there was no color map of the vascular flow inside the foci. A densitometric study revealed low acoustic density, on average 61.7 ± 15.2 CU. The difference in this indicator between the groups is statistically significant (p < 0.05). The vascularization index was determined in 7 patients and on average amounted to 0.1%. Conclusion The ultrasound picture in orbital GPA differs depending on the stage of the inflammatory process, which allows using this non-invasive and accessible technique to assess the activity of the inflammatory process. Key words: granulomatosis with polyangiitis; orbital pseudotumor; inflammatory activity; ultrasound diagnostics