1. A method for determining an extent of at least one of a pleural space and a pleural thickening, comprising the steps of: obtaining an image including at least one of the pleural space and the pleural thickening; segmenting lungs in the obtained image; constructing a chest wall image from the obtained image using a lung boundary obtained in the segmenting step; identifying ribs in the chest wall image; mapping a location of the identified ribs back into the obtained image; and determining in the obtained image the extent of the at least one of the pleural space and the pleural thickening between the identified ribs mapped back to the obtained image and at least one segmented lung.