Management of systemic vasculitis: contribution of scintigraphic imaging to evaluation of disease activity and classification.

The use of radio-isotope-labelled leucocyte scans has become established as a non-invasive and accurate means of diagnosing a variety of inflammatory conditions. We report a retrospective study on leucocyte imaging in the management of 50 patients with systemic vasculitis. Leucocyte imaging was useful for detecting unsuspected sites of disease and monitoring disease activity. Scintigraphy was superior to conventional radiography or CT scanning for detecting and monitoring vasculitic involvement of the respiratory tract. The scans were useful for differentiating between Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA). There was a close and statistically significant relationship between the clinical diagnosis of WG and nasal uptake on leucocyte scans (p < 0.01), whereas in patients with MPA it was rare. Anti-proteinase 3 autoantibody specificity correlated significantly with nasal uptake of labelled leucocytes (p < 0.03). Leucocyte imaging is a useful non-invasive investigation in patients with systemic vasculitis.