Detection of pulmonary nodules with overlapping vs non-overlapping image reconstruction at spiral CT

The aim of this study was to analyze whether overlapping image reconstructi on increases number of pulmonary nodules detected at helical CT. Forty-eigh t helical CT scans (21 with a slice thickness of 10 mm; 27 with a slice thi ckness of 5 mm) of patients with known pulmonary nodules were reconstructed both with overlapping and non-overlapping image reconstruction. Two reader s recorded number and size of pulmonary nodules as well as diagnostic confi dence. With overlapping image reconstruction each reader diagnosed more pul monary nodules (slice thickness 10 mm; +9.5 and +11.9%, both not significan t) and more "definite" nodules (slice thickness 10 mm; +20.3%, p < 0.05, an d +30.8%, p < 0.005; slice thickness 5 mm; +18.0 and +17.0%, both p < 0.05) . Nodules diagnosed with overlapping image reconstruction only were almost exclusively smaller than the slice thickness. The increase in number of nod ules detected was not associated with a decrease in diagnostic confidence. Overlapping image reconstruction improves detection of pulmonary nodules sm aller than the slice thickness at spiral CT.