Pulmonary Nodules CT Scan

Pulmonary nodules are a common incidental finding on imaging studies, particularly multidetector computed tomography (MDCT). Advances in CT have improved characterization of nodules, helping to differentiate benign from malignant lesions noninvasively. Many nodules, however, remain indeterminate and require either temporal characterization to confirm stability or invasive assessment for a definitive diagnosis. A pulmonary nodule is defined as a round opacity, at least moderately well marginated and no greater than 3 cm in maximum diameter. Solitary pulmonary nodules (SPNs) may be caused by a variety of benign and malignant disorders. CT is significantly more sensitive than standard radiography for nodule detection, and with the increasing use of MDCT, small nodules of less than 1 cm are detected with increasing frequency. As a result, small benign lesions that would have otherwise been invisible on radiographs are now being detected. Low-dose CT has proved to be 3 times more sensitive than chest radiography for detection of non-calcified nodules. Of those patients with nodules, 11% were eventually diagnosed with lung cancer, the majority of whom at stage I of the disease. The introduction of MDCT has minimized misregistration artifacts and improved spatial and temporal resolution, thereby, improving nodule detection and characterization. Intravenous contrast administration is not routinely required. However, it may prove useful in cases in which the suspected nodule is located adjacent to the mediastinum or hilum or if there is a suspicion for an arteriovenous malformation. Routine reconstructions typically are composed of 5-mm sections with a non-targeted field of view. A targeted field of view with thin sections (11.5 mm) through an area of interest, however, greatly improves spatial resolution and hence nodule assessment.