Pulmonary nodule distribution modeling as a diagnostic tool for HRCT image analysis

In an attempt to improve pulmonary CT scan reading, a computerized model of lung has first been elaborated. The secondary lobule was used as structuring lung element. The entire organ was composed of several lobule layers and of broncho-vascular trees. As pulmonary nodule distribution modes may turn the diagnostic onto specific pathology type, it is very important to define them as precisely as possible. Seven nodule distributions have been modeled: homogenous, peripheral, centrolobular, pleural, lymphatic, and broncho-vascular. A software tool was developed which allows the radiologist to spread nodules either in the whole lung or in anatomical lung areas, using one or more defined distribution modes until the simulated images mimic the CT scans under analysis. First results show a good agreement between scans and synthesized slices. The software tool described here help the physician to determine the true underlying nodule distribution involved in the pulmonary CT under analysis and lead then to a more precise diagnosis. Moreover, it can be used for radiologist education and training.