Overview of two years of clinical experience of chest tomosynthesis at Sahlgrenska University Hospital.

Since December 2006, approximately 3800 clinical chest tomosynthesis examinations have been performed at our department at Sahlgrenska University Hospital. A subset of the examinations has been included in studies of the detectability of pulmonary nodules, using computed tomography (CT) as the gold standard. Visibility studies, in which chest tomosynthesis and CT have been compared side-by side, have been used to determine the depiction potential of chest tomosynthesis. Comparisons with conventional chest radiography have been made. In the clinical setting, chest tomosynthesis has mostly been used as an additional examination. The most frequent indication for chest tomosynthesis has been suspicion of a nodule or tumour. In visibility studies, tomosynthesis has depicted over 90 % of the nodules seen on the CT scan. The corresponding figure for chest radiography has been <30 %. In the detection studies, the lesion-level sensitivity has been approximately 60 % for tomosynthesis and 20 % for chest radiography. In one of the detection studies, an analysis of all false-positive nodules was performed. This analysis showed that all findings had morphological correlates on the CT examinations. The majority of the false-positive nodules were localised in the immediate subpleural region. In conclusion, chest tomosynthesis is an improved chest radiography method, which can be used to optimise the use of CT resources, thereby reducing the radiation dose to the patient population. However, there are some limitations with chest tomosynthesis. For example, patients undergoing tomosynthesis have to be able to stand still and hold their breath firmly for 10 s. Also, chest tomosynthesis has a limited depth resolution, which may explain why pathology in the subpleural region is more difficult to interpret and artefacts from medical devices may occur.