A validation study of a new software for computed tomography lung measurement

The use of computed tomography (CT) in the management of ALI/ARDS patients is quite common, due to the possible additional clinical information and the influence on the patient's treatment. With the new spiral CT scan it is possible to measure the total lung volume, the percentage of lung tissue and gas, there being a linear correlation between the physical density and the CT coefficient of attenuation.

The aim of this study was to evaluate in vitro the new computer program 'Maluna' (University of Mannheim, Germany) dedicated to measuring the lung volume, weight and gas/tissue ratio.

A series of different known volumes of water (100, 500, 1500 and 2000 ml) were studied. In addition, the contrast material was diluted with water to obtain solutions of increasing concentrations (0, 0.5, 1, 1.5, 2.5 and 5%). The spiral CT was performed at 120 KV and 240 mA. Each CT section was manually delineated by a physician. The total volume was computed as the total number of voxels present in a given region times the volume of the voxels, while the CT number was directly related to the physical density.

Figure 1 shows the Bland–Altman analysis between the known volumes of water and the measured volumes by 'Maluna'; Fig. 2 shows the linear regression between the CT attenuation coefficient with increasing concentrations of contrast material in the solution. These data show that 'Maluna' is able to correctly compute the volumes and CT number.

Figure 1

(abstract P110)

Figure 2

(abstract P110)