Ventilation perfusion scintigraphy and lung function testing to assess metal stent efficacy

Stent implantation in malignant bronchial stenoses is a highly effective method of providing symptomatic relief by restoring bronchial patency. Whether an improvement in ventilatory conditions is paralleled by an increase in blood flow and gas exchange has not yet been determined. Methods: Fourteen patients with malignant, high-grade obstruction of bronchi who had metal stent implantation were investigated. Before the intervention and again 8 days afterward, both quantitative technegas ventilation and (99m)TC-MAA perfusion scans (V/Q scans) and lung function tests were performed. Results: Stent implantation was successful in all patients, with a significant reduction in the degree of bronchial stenosis (prestent: 93% ± 1.5%; poststent: 16% ± 3.5%). After stent implantation, ventilation scintigraphy revealed an improvement in tracer deposition by 65% (prestent: 37% ± 8%; poststent: 61% ± 6%; p<0.05) within the affected lung. A complementary increase of 71% by perfusion scintigraphy was obtained (prestent: 27% ± 4%; poststent: 46% ± 5%; p<0.01%). Based on scintigraphic criteria, stenting was successful in 93% (n = 13) of all patients. Lung function studies performed after the intervention showed significant improvement in vital capacity (VC, p<0.01), forced expiratory volume in 1 sec (FEV₁, p < 0.05), peak expiratory flow (PEF, p<0.05), arterial oxygen (PaO₂, p<0.05) and carbon dioxide (P(a)CO₂, p<0.05) tension, and oxygen saturation (p<0.05). Conclusion: Stenting of malignant high-grade bronchial obstructions leads to an increase in bronchial patency and in activity distribution of both ventilation and perfusion scintigraphy of the affected lung, accompanied by significant improvement in lung function parameters.