2D or 3D measurements of pulmonary nodules: preliminary answers and more open questions

Accurate size measurements of pulmonary nodules on CT are a prerequisite for accurate nodule management, given that all current management guidelines are based on nodule size (1-4). Nodule size is most commonly measured manually using electronical calipers, with the long- and perpendicular short-axis being measured on two-dimensional images (5). As a management criterion alternative to size, three-dimensional nodule volume has been discussed in the literature (6) and has also received mention in recent management guidelines for incidental nodules (1,3).