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Leukocyte scintigraphy with 99mTc-exametazime-labeled leukocytes is not useful for follow-up of systemic vasculitis.

BACKGROUND
The prognosis of systemic vasculitis, for instance Wegener's granulomatosis (WG), was greatly improved by the introduction of immunosuppressive treatment. However, relapses are frequent and predictors are scarce. 111In-leukocytes have been found to indicate unknown manifestations of WG and to predict later relapse. We prospectively investigated the value of 99mTc-Exametazime (99mTc-HMPAO)-labeled leukocytes with regard to specific patterns and for their usefulness in the follow-up of patients with WG.


METHODS
The vasculitis group consisted of 8 patients with WG and 2 with idiopathic necrotizing glomerulonephritis (ING). Seven patients with different inflammatory diseases served as controls. Leukocyte labeling with 99mTc-HMPAO was done using a slightly modified Hammersmith protocol. Cell viability after labeling was verified in vivo by the exclusion of early lung and splenic uptake and in vitro by means of propidium iodide and FACS analysis. Static gamma camera images from the head, chest, abdomen, and pelvis were obtained up to 18 hours after injection of approximately 300 MBq 99mTc-HMPAO-labeled leukocytes. Scintigrams were analyzed visually; for semiquantitative analysis ROIs were drawn over the nasal region, the right lung, kidneys, and liver.


RESULTS
Increased nasal leukocyte accumulation was found in 7/8 patients with WG and in 2/2 patients with ING. Of 2 patients who had a relapse 6 months later, one presented with, and one without nasal uptake. The kidney/liver ratio was higher in controls (0.24 +/- 0.07 vs. 0.37 +/- 0.11, p < 0.05). Distinct to moderate lung uptake was observed in 2 patients with WG and in one with ING. No correlation was found between scintigraphic results, medication, ANCA status or cretinine levels.


CONCLUSION
Nasal leukocyte accumulation is increased in systemic vasculitis, independent of the immunosuppressive treatment and later clinical course. However, this finding is not specific for vasculitis. 99mTc-HMPAO leukocyte scintigraphy failed to indicate or exclude a later relapse and is therefore not suitable as a diagnostic tool in the management of patients with systemic vasculitis.